Technical Articles

This section includes separate Winemaking guides for Grape wines and Country wines, especially written with the beginner in mind.  There are a wide variety of articles covering relatively more advanced techniques such as making sparkling wines, measuring the Free SO2 content of your wine, the finer points of making white wines (pros and cons, oxidation).

The “Summary” series of articles are linked to the EDWG Home Winemaking Guide, but are also stand-alone articles covering key parts of the winemaking process such as SO2, yeast fermentation, Malolactic fermentation, Acidity and pH, Cleaning and Sanitation, Fining and Stabilisation, racking, oak and other fundamental topics. These are the basics of winemaking technique in which every winemaker, amateur or professional, must become “unconsciously” skilled.

Airlocks and Bungs
Cleaning and Sanitising
Cork Care
Fining and Stabilisation
Malolactic Fermentation
Measures, quantities and units   
Oak and Home Winemaking
Oxidation
pH - Related to Acidity
Pros and Cons During White Wine Making
Racking
Red Wine Making Process Chart
Smelly Wines         
Sulphur Dioxide 
Tannin Additions
Testing and Adjusting Acid Balance

Testing your wine for free SO2
White Wine Making Process Chart
White Winemaking and Oxidation
Yeast Fermentation

Sparkling Wine Presentation
Presentation - Caring for your Wines (Audio)
  (30 Dec 2009) Stan Gower
(17 Nov 2009) Gary Campanella
(30 Dec 2009) Stan Gower
(15 Mar 2010) Bruce Black
(20 Nov 2009) Stan Gower
(20 Nov 2009) Stan Gower
(15 Feb 2010) Michael Williamson
(20 Nov 2009) Gary Campanella
(17 Nov 2009) Stan Gower
(20 Nov 2009) Reon Vuglar
(30 Dec 2009) Stan Gower
(30 Dec 2009) Gary Campanella
(20 Nov 2009) Paul Finn
(20 Nov 2009) Stan Gower
(17 Jul 2010) Bruce Black
(08 May 2010) George Wright
(20 Nov 2009) Bruce Black
(20 Nov 2009)  Gary Campanella
(20 Nov 2009)  George Wright
(20 Nov 2009) Gary Campanella
(July 2014) Loic Le Calvez
(July 2014) Lindsay Corby

Airlocks and Bungs   

Written by Stan Gower
Wednesday, 30 December 2009 03:08

The discussion here is limited to using airlocks and bungs in glass demijohns; and airlocks plastic beer fermenters. Some special issues arise when using airlocks and bungs in oak barrels.
 



 
 

The purpose of a bung is to fully seal off a wine container after the fermentation processes have finished, and no more gas is being produced.

The photo shows one airlock design, and also shows a bung, a stopper without a hole in it. The purpose of an airlock is to allow gas generated during the fermentation of the wine to escape from the container while not allowing air, (oxygen) back into the container.

There are various designs of airlocks, but basically they rely on water to let the gas bubble out. Airlocks can also be used for the longer term, after fermentation has ceased, but this requires certain extra steps to be taken, which are described below.  
 

 

Cleaning and Sanitising       

Written by Gary Campanella          

Tuesday, 17 November 2009 11:35

 

1. Introduction

Wine is a food product. Our common sense tells us that whenever we prepare food, we use clean utensils and surfaces. In the same way it is very important to follow sound cleaning practices around anything that comes in contact with your wine.

 

The aim of cleaning is to remove visible contamination; this may just be dust, cobwebs and light deposits through to caked on sediment and mould.

 

Sanitising is the step where you further treat a thoroughly clean surface or piece of equipment to reduce the level of microbes present to a level acceptable for the winemaking process.

 

Sterilisation is something that is beyond what we are trying to achieve for winemaking. Sterilisation refers to a surface being completely free of bacteria and other microorganisms. You certainly want this during surgical procedure, but not necessarily in the winemaking shed! Besides being practically impossible to achieve in a home winemaking situation, it is not even required to make great wines. The naturally high acid and alcohol levels present in wine make it an undesirable habitat for organisms that do us harm.

 

Proper cleaning and sanitisation goes along way to ensuring your lovingly made wine does not develop nasty tastes due to organisms that, like us, happen to love living with wine!

 

2. Cleaning and Sanitising Process

Cleaning and sanitising are separate steps; an effective sequence that is suitable for the home winemaking situation and applicable to anything that comes into contact with your wine is as follows:

 

Rinse equipment with clean flowing water

If have access to it, use hot water (50 to 70 C) on equipment that can tolerate it, otherwise cold water will do.

Use appropriate caustic cleaning agents for each type of equipment to remove scale and deposits. Thoroughly wet the surface to be cleaned with a generous quantity of the cleaning solution, scrubbing as required to remove deposits. Persistent deposits may need soaking.

Sanitise with a suitable solution, generally Sulphur Dioxide/Citric acid based. Flood the surface to be sanitised with a generous quantity of the sanitising solution leaving it in contact for a few minutes.

Rinse all sanitised equipment with cold water.

Drain all cleaned and sanitised equipment so that there little, preferably no residual water.

 

It is important that all equipment treated in this way be dry, completely free of any solids and with no remnant smells.

 

New and previously cleaned equipment that has no solid deposits may not need treatment with a cleaning solution. A rinse with clean water to remove dust and cobwebs is all that is required for the cleaning step in this case. The sanitisation step must then be performed as described above.

 

3. Cleaning and Sanitising Solutions

3.1 Cleaning solutions

The most appropriate cleaning solution to use is Sodium Percarbonate, also known as Oxyper. It is readily available at home wine and brewing shops and is inexpensive.  Avoid using Chlorine, soap and detergent based cleaners, perfumed cleaners, as these are difficult to rinse away thoroughly, plus there is the ever present risk of impacting the taste of your wine.  Chlorine based cleaners are to be particularly avoided for the beginning home winemaker as Chlorine is contributing factor for "cork taint"

 

Make up a cleaning solution by dissolving Sodium Percarbonate at a rate of 8 to 12 grams (three level teaspoons) per litre in clean water. It is best to dissolve your measured dosage in a small amount of hot water and then mix with cold water for the desired volume of cleaning solution.

 

There are many commercial variants of Sodium Percarbonate based cleaning agents. So check the recommended dosage on the packet of whatever you purchase. The main thing is to ensure that you purchase a caustic-based cleaning agent containing NO chlorine, soap or detergent.

 

3.2 Sanitising Solutions

Potassium Metabisulphite (PMB) is the most widely used and effective sanitiser for winemaking. Its sanitising effectiveness is enhanced with the citric acid. The acid content of a Sulphur-Citric sanitising solution also serves to neutralise surfaces previously cleaned with caustic solution.

 

An effective sanitising solution can be made by dissolving 17 grams of PMB (3 level teaspoons) in 1 litre of water. This is best made by dissolving the measured dose of PMB powder in 500 millilitres of warm water, and then add cool water to make 1 litre of sanitising solution. To make Sulphur-Citric solution add 17 g (3 teapoons) of Citric Acid to the PMB solution.

 

As an alternative to Sulphur-based sanitising solution there are “non-rinse” solutions that are based on compounds that produce hydrogen peroxide when dissolved in water. Hydrogen Peroxide acts as a strong oxidizer, killing microbes as it bubbles in vats, hoses and barrels. Its bubbling action makes it especially good for hard to scrub places like the inside of siphon hoses. Like Hydrogen Peroxide, however, it does need an acid rinse in order to neutralize the surface.

 

Proxitane and Brewshield are liquid, Hydrogen Peroxide-based sanitising solutions that are readily available from home winemaking and brewing shops. Finally, there are iodine-based sanitisers such as iodopher.

 

4. Safe Handling of Cleaning and Sanitising Solutions

Always wear gloves when preparing, mixing and using cleaning and sanitising solutions. Remember the cleaning solution is caustic and will irritate and possibly burn sensitive skins.

 

Always use Sulphur-based sanitising solution in a well ventilated area; Inhaling Sulphur fumes that may be concentrated as you reach down into a fermentation vessel can cause throat and nose to become irritated.

 

5. Good cleaning and sanitising practices

Clean and dry equipment that is going into long-term storage;

Clean and sanitize a piece of equipment before you use it;

Clean well, making sure no colour or smell remains;

Clean up wine spills as soon as they occur as they will attract insects and microorganism that are harmful to wine

  

References:

1. Rankine, B. Making Good Wine, 2004

2. Pambianchi, D. Techniques in Home Winemaking, 2008

3. Crowe, A. The Winemakers Answer Book, 2007

 

Last Updated on Thursday, 25 March 2010 12:15

 

Cork Care         
Written by Stan Gower        

Wednesday, 30 December 2009 03:12

 

There are a lot of different options when buying corks. There are new solid cork corks; agglomerated corks made from reconstituted used corks or small fragments of new cork; and there is an in between option that used agglomerated cork, but it has a 5mm slice of new cork attached to each end.

  Like most things, the better the cork quality the more expensive the corks. If you choose to use cheap agglomerated corks, they should only be used when you intend to only keep the wine for a short period, say 12 months or less.

 The photo also shows a cheap cork that has been in the bottle for about 18 months, and the wine has leeched right through the cork, and is actually dripping off the lip of the bottle. If it is intended to keep this wine, (and it is still OK to keep), then the cork should be replaced with a better quality cork.

Naturally different cork suppliers may vary in how they supply corks, so you need to buy from a reputable supplier.

A typical new pack of corks may have instructions printed on it such as the following: - "Newly purchased corks in an unopened pack don't require sterilization. The silicon coating on the cork helps it slide through the corker. For this reason, avoid contact with hot water............etc."

PVPP. Bittering and browning

Egg white.  Egg wite can remove bitter tannins from red wine.  They can be bought as a powered form, such as Clarouge, or a solution can be prepared from fresh eggs.  To do this add one part egg to ten parts water that has had a little salt (5g/l) added.  Whisk the mixture, but do not make it foamy, and add to the wine at a rate of 50-400mg egg per liter of wine.  Powdered egg is also diluted in ten parts water, and Clarouge states it can be used at 50-200mg/l for clarification and 400-2000mg/l to remove bitterness.
 

Casein.  Removes bitterness and browning in white wine.  You could use milk at 2-10ml per liter of wine, or you can mix a powder such as Protoclar K which is pure potassium caseinate.

 

Copper (as Cu2SO4).  Hydrogen Sulphide (rotten egg smell), reacts to form copper sulphide which settles to the bottom.  Doses are very low, and extreme care is required in the measurements because copper is toxic.  Bench trials are mandatory to determine the minimum dose required for the same reason.  If the correct dose is chosen all the copper reacts and is removed, but if too much is used it will remain in the wine.  If this happens the wine should be fined with bentonite or casein to remove the excess copper.
 

Oxygen (as air).  Hydrogen Sulphide.  Aerating a wine that is protected by SO2 will cause the hydrogen sulphide to form sulphur which will settle to the bottom.  The wine must be racked after a while or the sulphur will be reduced back to hydrogen sulphide.  The wine should be vigorously aerated, but take care not to overdo this or the wine will become oxidised.  For small batches this is often achieved by pouring from one container to the next (called splash racking), and for larger batches the wine is pumped from the bottom to the top of the tank with plenty of splashing (called a pump over).

Fining and Stabilisation    
Written by Bruce Black
Monday, 15 March 2010 14:00

1. Introduction
All the processes described in this section (except microbial stabilisation) are designed to remove undesirables from your wine. They are undesirable because they add an unwanted taste or odour to the wine or detract from its appearance. Often the flavours and odours will mask the real character of the wine, and the goal is to bring out this character.

However, fining agents will also remove to a greater or lesser extent, desirable flavours and aromas. For this reason instructions will always include a range of addition rates, and the winemaker should always carry out trials on small samples to determine the addition rate that produces the best result. Often these trials will include different fining agents to determine which is most effective on the particular problem this wine displays.

It should also be noted that any handling of the wine runs the risk of contamination and oxidation. To minimise these risks wine should always be well protected by potassium metabisulphite prior to fining, and handling procedures should be kept to a minimum. Generally white wine will require more fining than red, but it can be applied to either as the need arises. Because of the protection tannins provide, red wine is somewhat more robust if fining is required.

2. Fining
These are the most common types of fining agents used by amateur winemakes, but there is a very extensive list of products that can be added to wine to achieve a variety of results.

Bentonite. Removes protein and will help clarify a cloudy wine. Usually my first and last agent for clearing stubborn wine. Very gentle. Suspend in water and add to wine, then rack wine when bentonite has fully settled (1-3 weeks). Used for heat stabilisation (see below). Forms light lees, so there is some wine loss when using this. Also requires the addition of quite a bit of water to the wine.

PVPP. Bittering and browning
Egg white. Egg wite can remove bitter tannins from red wine. They can be bought as a powered form, such as Clarouge, or a solution can be prepared from fresh eggs. To do this add one part egg to ten parts water that has had a little salt (5g/l) added. Whisk the mixture, but do not make it foamy, and add to the wine at a rate of 50-400mg egg per liter of wine. Powdered egg is also diluted in ten parts water, and Clarouge states it can be used at 50-200mg/l for clarification and 400-2000mg/l to remove bitterness.

Casein. Removes bitterness and browning in white wine. You could use milk at 2-10ml per liter of wine, or you can mix a powder such as Protoclar K which is pure potassium caseinate.

Copper (as Cu2SO4). Hydrogen Sulphide (rotten egg smell), reacts to form copper sulphide which settles to the bottom. Doses are very low, and extreme care is required in the measurements because copper is toxic. Bench trials are mandatory to determine the minimum dose required for the same reason. If the correct dose is chosen all the copper reacts and is removed, but if too much is used it will remain in the wine. If this happens the wine should be fined with bentonite or casein to remove the excess copper.

Oxygen (as air). Hydrogen Sulphide. Aerating a wine that is protected by SO2 will cause the hydrogen sulphide to form sulphur which will settle to the bottom. The wine must be racked after a while or the sulphur will be reduced back to hydrogen sulphide. The wine should be vigorously aerated, but take care not to overdo this or the wine will become oxidised. For small batches this is often achieved by pouring from one container to the next (called splash racking), and for larger batches the wine is pumped from the bottom to the top of the tank with plenty of splashing (called a pump over).

Stabilisation
Stabilisation is a process for ensuring the wine doesn't undergo any undesirable changes in the future. There are three main types of stability:

Heat stability; fine white wines with bentonite to remove protein which may coagulate (like egg soup) if the wine gets hot. If you want, you can test the wine by warming a sample and checking for any soupy haze prior to or after fining. If you are sure your wine will always be kept in cool conditions and you are happy with the clarity you can skip this step, but beware the back seat of the car if you are going out! It is not required for red wines as the natural tannins achieve the same purpose.
Cold, chill to near freezing to remove potassium bitartrate which will precipitate when the wine is chilled. I leave my wine in the shed over winter before bottling, and although it never goes below 10C this seems to be adequate to prevent any problems in the fridge. Although reds will not be refrigerated it's advisable to rack them off any sediment during winter to prevent crystals forming in the bottle during cold weather or in the cellar.

Microbial: add potassium metabisulphite to bring the free SO2 to a level that will prevent bacterial growth. For sweet wines also add potassium sorbate to prevent yeast refermenting the wine in the bottle. The amount of SO2 required will depend on the pH of the wine (see chart below). As a guide 1g of potassium metabisulphite will add 56ppm total SO2 to 10 liters of wine, but some will be bound and some will be free. The ratio varies depending on the wine and the only way to be sure of the free SO2 level is to measure it.

 

Malolactic Fermentation          
Written by Stan Gower
Friday, 20 November 2009 21:30


The standard dose is approximately 1gm of malolactic culture per 100 litres of must. Read the instructions on the packet, purchased from a reputable supplier

SO2, (PMS) will inhibit the malolactic process. This is why a maximum of 100ppm of PMS is added at the crushing stage, and no further PMS is added at pressing, and until after malolactic fermentation is completed.

See the EDWG article on SulpherDioxide for more details.

The stage of wine making to inoculate wine with Malolactic culture.
This can vary. Some leave it until yeast fermentation is completed, but this can have the disadvantage that there is more alcohol present which may make it harder for the culture to work. I usually inoculate after the yeast fermentation has been going for about 3 days. This has the added advantage that the wine is warmer because of the yeast fermentation.

The actual bacterial activity starts near the end of alcoholic fermentation, Getting the bacteria acclimatized and in the optimum warm environment during ferment is good. The yeast fermentation binds any SO2 and creates the warmth for optimal MLF conditions

Preparation.
Re-hydrate the bag contents, 5 gms of culture, in 500mls of distilled or demineralized water at a temperature of 20 - 30deg C. Shake the suspension to eliminate any lumps, and to enhance contact with the fluid. Wait 15 minutes, and then add the suspension to the wine.

I added the suspension by dividing the 500 mls of suspension according to the number and sizes of the wine containers.

For example, with the following containers: - 6X25 litre and 2X10litre,

The suspension needs to be divided into 7 equal lots, one of which will be split between the two smaller containers.

500mls ÷ 7 = 70 mls into 6 containers, and split the past 70mls between the two smaller containers.

Very important. Throughout the division and pouring into the wine, keep the suspension stirred.

Keep the wine temperature at between 18 to 22 degress C for the 4 to 6 weeks that it takes for the malolactic fermentation to be completed.

After about 4 weeks, send samples of 4 or 5 containers, each sample in a 12ml (minimum) screw cap tube, for analysis to check the progress of the process.


pH is affected by malolactic fermentation: - The removal of Malic acid by malolactic fermentation will increase pH by 0.1 to 0.15.

1. Progress of Malolactic fermentation.
With the small containers often used by amateur wine makers it may be hard to tell whether the “fermentation” process is going or not. Ideally you see activity through the air lock - a bubble every 5 minutes is active. If you are in the same room you'll probably hear it.

In a barrel you can hear crackling when you put your ear to the bunghole; it is less noticeable in smaller volume vessels but you can try it.

Knowing when MLF has completed is best determined by testing. Use a good testing lab.

2 Temperature of “fermentation”.
If you can’t quite keep the temperature over 18’C, but can only get it to 14 – 15’C the process will continue, but will go more slowly.

3. Transport and storage of Malolactic culture.
It is best to buy fresh culture, preferably not more than a week before using it. The supplier will store it in the freezer. Take a cold container to transport it home, and immediately put it in the normal part of the fridge, until used.

If it kept for a longer period it should be kept in the freezer, and it is important to have it in an airtight container. It is a live bacterial culture; it will just lose some of its activity. The manufacturers say it loses some of its activity even in the freezer after a year. They advise using a higher inoculum (higher dosage) with old culture. It tolerates transport (postage) over a few days with just a cold pack so I imagine a few days above 0oC but below 10oC would be OK

4. PMS, SO2 and malolactic “fermentation.”
All SO2 is bound during fermentation so additions <(up to / not exceeding) 50ppm total before fermentation, (at crushing), won't inhibit MLF.

5. Adding SO2, PMS once malolactic “fermentation” is complete.
Appropriate sulphur dioxide addition will knock out all unused malolactic culture. Residual lactic acid bacteria, after they have used up all of the malic acid, can work on other substrates and produce spoilage products like volatility and mousiness, so it is imperative to add SO2 once MLF is complete.

6. To use, or not to use; malolactic “fermentation?
All commercial dry reds (of the style we in Australia like) go through MLF to gain complexity and stability as they age in barrel. As a home winemaker, if you prefer simple fruitiness then you don’t need MLF but MLF also rounds a wine, a benefit if the wine is a little acidic and doesn’t have an oak barrel for maturation. For Chardonnay the wine must have depth of flavours and texture to benefit from the butteriness of MLF

7. Oxidation and Malolactic “fermentation”.
While MLF is in progress there is no danger of oxidation because carbon dioxide is being produced.

8. How different are the different cultures?
Not very, they are all oenococcus oeni – the desirable bacteria, some have been selected for very harsh conditions (v high alcohol, low pH)

Use the cheapest one from a reputable supplier and have had no problems. It is Malolac from Deltagen who actually grow the culture (no middle men to raise the price?)

9. Benefits and disadvantages of malolactic "fermentation."
- Rankine lists the following, in brief: -

Advantages: - Softer and reduced acidity; Important for Australian high acid wines; stability improved; if all malic acid
consumed, will *not happen in bottle; effect on wine quality is debatable; may add complexity in certain situations.

* (it will not happen in bottle provided correct amount of PMS, SO2 is added before bottling)

Disadvantages: - Breakdown of tartaric acid, serious but also rare; loss of fruit aroma, “off” characters, many of which slowly disappear.


Reference
Rankine, B. Making Good Wine, 2004

Last Updated on Tuesday, 23 March 2010 21:05      

Measures, Quantities and Units      

Written by Stan Gower     
Friday, 20 November 2009 21:30   

Some of the most difficult things facing a new wine maker are: -

1. Different terms / units used to describe the same thing.

For example: 1 milligram / litre. (1 mg/l) used interchangeably with 1 part per million. (1 ppm)…To understand that these two terms mean the same thing, follow: - 

- 1 mg = 1/1000th of a gram …
 1 gallon water = 10 lb….-
 1 pint water = 1.25 lbs
- 1 litre of water = 1.759 pints…
(pints to litres = 0.568) Used interchangeably
1 litre ÷ 0.568 = 1.7590pints…1.25 lbs X 1.759 pint …= 2.1988 lbs / litre
(Alternatively, gallons to litres = gallon X 4.546; 10 lb / gallon ÷ 4.546 = 2.199 lb / litre)  

X 16 oz/ lb =
35.18 oz per litre
 X 29.4 gm/oz =
 1034 gm weight per litre  

X 1000 mg / gm =
1,034,000 mg weight per litre
 (near enough to 1,000,000) 

so 1 litre weighs aprox. 1,000,000 mg..
so 1 mg / litre = aprox. 1 part per million 

2. Additions by weight of small quantities of any chemical

For example
1mg/litre=1ppm
So for 100ppm in a 25 litre demijohn
=(0.1gm/litre X 25 litres) = 2.5 gms.

3. Understanding signs for “more than”, and “less than”
The < sign means "up to",  or  “less than”.
The > sign means “over”    or  “more than”.

4. Measuring small quantities with inexpensive weighing equipment. 

If, like me you, only have an old photographic chemicals balance that weighs in ounces rather than grams, and you don’t want to go to the expense of buying another balance, then you will need to be able to convert quantities from ounces to grams.  

The weights supplied with my balance are;
- 4, 2, 1, ½, ¼ounces    

The following table shows how to convert those different size weights from ounces into grams. 1 kilogram (kg)   = 1000 grams (gms)  = 2.2 pounds (lb)  X  2.2 lb by 16 (I lb has 16 oz.)
=  35.2 ounces (oz) So 1000 gms  = 35.2 oz
Divide 35.2 oz into 1000 gms So  1 oz = 28.4 gms. 
So the weights that I have on my photographic chemical balance shown below are: -  

4 oz   =   113.6 gms
2 oz   =     56.8 gms
1 oz   =     28.4 gms
½ oz  =    14.2 gms
¼ oz  =      7.1 gms
 

How to measure a small quantity.  

Let’s suppose I want to add 30 parts per million (ppm) of PMS to 25 litre of wine.
Go to the 30ppm table above

1.
Find the 25 litre value in the “No of litres” column

2. Read the number of gms in the “gms” column opposite 25 litres, =   0.75 gms.
So to add 30ppm to 25 litre containers I need to add 0.75 gms of PMS. 

See the photo above.

There I have weighed ¼ oz of PMS, (my smallest weight)

¼ oz = 7.1 gms. I need to divide this amount into smaller parts to get 0.75 gms
To work out how many parts, I divide 7.1 gms by 0.75 =   9.47. For practical purposes, I will call it 9

So now I need to divide my ¼ oz into 9 parts to get 0.75 gms.
There are two different ways that I can divide up the ¼ oz of PMS into 9 parts. 

METHOD 1.  

 

I simply smooth out the PMS onto a piece of grease proof paper and push the edges into a rectangle with a knife.

Now divide the squared , smoothed pile into 3 sections length-wise, and then divide each row into 3 parts.

Each pile of PMS is now close enough to 0.75 gms

So I add one pile of PMS to each 25 litre container of wine, = 30ppm.

METHOD 2. 

Measure a small quantity of water that is easily divisible into 9 parts, say 90 mls.
Dissolve the whole ¼ oz of PMS in the water
Add 1/9th =10 mls of the solution to each 25 litre container. 

Important. Check that all of the chemical has been able to be absorbed into the small quantity of water chosen. If it has not all dissolved, you will need to select a bigger quantity of water. 

The smallest quantity that will dissolve all of the chemical is best, so as not to dilute the wine too much.  

5.     Understanding simple measures for adding chemicals  

APPROXIMATE WEIGHTS of dry chemicals PER TEASPOON FULL. 

NOTE; It is best to buy a proper teaspoon measure, such as a home bread baking tea spoon measure.

One standard teaspoon of :
Yeast  2.8 gms
DAP  (Yeast nutrient)      5.0 gms
Tartaric acid  5.0 gms
Potassium metabisulphite. (PMS)    5.4 gms
Tannin  2.8 gms
PVPP (synthetic fining agent)  1.2 gms
Bentonite  3.4 gms  

6.  VISUALIZING 1 part per million.  

It can be hard to visualize 1 part per million,(1 ppm)  OR 100 ppm OR other multiples of ppm, as it compares with the volumes of wine that we deal with.  

The sketch gives an APPROXIMATE idea of these quantities.

NOTE CAREFULLY. This sketch shows ppm by VOLUME, which could be very different from ppm by WEIGHT.  

The sketch is drawn to a scale of 4/10th of full size
Full size is 300mm on each side of the cube, (in old terms 1 foot cube.)
1 foot cube = approximately 28 litres  ppm_visual

 

Last Updated on Wednesday, 23 December 2009 10:58    
 

Oak and Home Winemaking     
Written by Michael Williamson
Monday, 15 February 2010 08:08

1. Introduction.
Oak has a place in almost every winemaker’s process, but the timing of use, type, size or quantity of oak and extent of use will vary depending on the type of grapes, style of wine desired, the scale of wine production, as well as the philosophy of the winemaker.

The use of oak can vary between the following styles that you may be interested in:
- Fresh, light, ready-drinking wine
- Refined, aged wine of a particular style
- Fruit driven, intensely flavoured wine
- Experimental or unusual styles
- Unusual (or less common) grape varieties
- And of course whether the wine is made from grapes or other material, eg country wines.

Oak flavour traditionally was imparted to wine only by use of oak vessels, eg barrels, that at its best transferred pleasant wood aroma and flavour to the wine. as well as softening some of the harsh flavours, for example from excessive skin or stalk contact.

Small amounts of oxygen enter the wine through the oak of a barrel soften tannins and add complexity. Also the water in wine slowly evaporates though the oak, increasing the concentration of alcohol, flavour and aroma compounds.

Direct contact of the wine with “raw” un-toasted wood would introduce aggressive undesirable wood flavours; therefore most oak in contact with wine is toasted to a light, medium or heavy toast. (A heavier toast with charring also exists which is not generally used with wine, but with specialised spirits).

The heavier the toast, the less aggressive woodiness, but a different spectrum of flavours emerge.

2. In Practice
Like most home-winemakers at some stage I want to create the harmonious combination of wine with oak. Where do I start?

If I am making 200 to 300 litres of wine then a barrel might be just what I need, but what if I am making a small quantity in a 5 litre flask? Or what if I plan to use a stainless steel tank, plastic drum or glass demijohns I already have?

Let me return to these issues again below after discussing the use of barrels in the home winery.

3. What Type of Barrel?
Whilst I might aspire to buying a new French or American Oak barrel at some stage in the future, both the cost and the overpowering intensity of the wood flavour imparted to the wine make this almost totally impractical for the home winery. A much more feasible alternative is a used barrel that has seen two or three vintages in a commercial winery and is sold at a fraction of the cost either directly from the winery, through a local cooperage or from a winemaking equipment supplier. Even better if the barrel has been re-shaved on the inside (several millimetres of wine-affected wood removed to expose clean oak) and toasted.

If you are uncertain of what type of oak to use I would recommend starting with French oak, medium toast which I think is the most versatile.

If I am making a white wine in a wooded style I need to use a barrel that has only ever been used for white wine. Even if a red wine barrel is re-shaved it can never again be used for white wine. If I want to keep my options open I can buy a barrel previously used for white wine, which I can then use for either red or white wine.

4. Buying
Before buying a second hand barrel I ask if I can smell the barrel. This may offend the person selling it to me, but I need to check if there is any hint of vinegary or mouldy smells particularly, or any other "off" odours that might suggest bacteria or contaminants that may spoil the wine. There's no alternative but to reject them.

5. Locating and Positioning Safely
You need to plan where you are going to keep your barrel during maturation – a place in the cellar that is not right in the way of all the other activities you need to do with your other wines and support it on a cradle which bears the weight on or near the hoops . I use two parallel beams 700x100x100mm held together on two "feet" 700x135x45mm. Together these four pieces of timber make a 700x700mm cradle – one for each barrel I am using.

Safety is a consideration as you do not want 200kg or more of a full barrel to roll off the cradle you are using.

I also use four wedges made from 100x100mm timber cut at 30 degrees to hold the barrel safely on the beam. Once in position I drill over sized holes through the wedges into the beam and loosely slip in large galvanised nails to hold the wedges, but also enabling them to be easily removed at any stage.

If you plan to fill and empty using a siphon you will want to plan to keep your barrel elevated above the height of any bucket you are planning to use. This is unnecessary if you use a wine pump. Further height can be gained by brick pillars made of alternating pairs of house bricks on each corner of the cradle.

6. Preparing and Sanitising for Use
If the barrel has been newly shaved and toasted, it needs to be conditioned before I use it, starting a few days ahead.

First I wet the oak properly for a few days to expand the staves so they expand tightly against each other and develop a waterproof seal. Skipping this step could result in a leaky barrel in later steps. This is a job for outside, but preferably in the shade if it is too hot.

I put a couple of buckets of water into the barrel and stand it on one end, filling the upper end piece with water and splashing it over the edges in all directions. I repeat this every so often over a few hours.

Later I put the barrel on its side and roll it around a bit wetting all staves on the inside and then stand it on the alternate end filling the end piece, splashing down the sides again.

I repeat this over a few days leading up to when I need to use the barrel.

The final steps are done close to the time of use.

(Some winemakers omit this next step, but there is a real risk of one of the types of over-oaking, in this case with the harsh toasting products, which is very common in beginner wine-makers. Whilst an over-oaked wine may moderate over many years or by fining, it is far preferable to avoid over-oaking in the first place.)

I fill the barrel with a bucket of very hot water and roll / rotate it in every direction, even on to the ends. When pouring out and discarding the water I note the colour. This needs to be repeated with fresh hot water several, sometimes many times until the dark colour diminishes to a pale tea colour.

To sterilise I put a bucket of a strong PMS solution (see the article on sanitisation) and again ensure the entire inside of the barrel is thoroughly sanitised by rolling rotating in every direction, including both ends. This needs to be done very thoroughly, so I spend about half an hour sloshing around the PMS solution.

The PMS needs to be thoroughly rinsed away, especially if you are filling with a fermenting wine so two thorough rinses with at least a bucket of water. Keeping the water moving around each time on all sides and ends

Then the barrel can be filled with wine - either filled two-thirds if a vigorously fermenting wine, just short of full if fermentation is almost complete or in the malo- stage, then bung with an air-lock is fitted. If I'm filling with a stable wine the barrel can be filled to the top, PMS adjusted and bunged.

7. Monitoring your Wine's Development
I sample the wine at least monthly to ensure the desired level of oak influence is being achieved. If the oakiness is too great, then the wine has to be moved to another container either an old inert barrel or a glass, stainless steel or food-grade plastic container. If none of these are available then bottling may have to be considered soon.

When evaporation has left a gap in the top of the barrel (ullage) I need to top up the barrel, either from a maintenance quantity of the same wine, or from a bottle of a similar wine. There is a technique of rotating the barrel to "2 o'clock" position to achieve a tight seal around the bung and a vacuum in the evaporating ullage (no longer around the bung and able to seep air), but this requires an extremely stable wine and very sound barrel and the risk of a cork blowing and losing 100 litres of wine before discovering it seems too great a risk. Not for the faint hearted.

Between rackings the barrel should be rinsed to remove any lees or wine and then "rumbled" with a length of stainless or galvanised steel chain inside with a bucket of hot water to remove the tartrate build-up inside the barrel. Rumbling is rolling the barrel around for an extended period of time, letting the chain fall and roll on all internal surfaces, including the end to scour the surface. Repeat with a new bucket of hot water as many times as necessary to clear the dark colour (in the case of red wine barrels). Follow up with sanitisation and twice rinsing before refilling.

A common error in amateur winemaking is over-oaking by neglecting to condition the oak by soaking away the harshest of the woody and toast products before adding to the wine. (In some styles of wine these are desired or are neutralised during active fermentation, but this should be only done by trial and error on small quantities of wine or with specific instructions to achieved a particular style of wine)

Today there are a vast number of choices for wine storage / maturation vessels, so as well as storage in oak vessels, the other ways to impart oak flavour to wine are planks, staves (or sticks), chips, shavings or powder additives. The decision of which to use will depend on where and how the oak flavour is intended to be added.

Reputable suppliers can advise on dosage rates and types to achieve a particular style and suiting the quantity and format of containers you will be using.

8. Consider the Alternatives
What are the other alternatives to barrels? Eg Planks, Staves (or sticks), Chips, Shavings, or powdered additives.
For a small vessel with a small opening, powdered additives, shavings or chips may be the only practical alternative because they may be the only oak you can physically get into the container. Typically dosage ranges for chips are 1 to 10g per litre. I have no experience with powders or shavings so I recommend the advice of a reputable supplier. Other than with powders, don't forget to soak the shavings or chips in hot or boiling water and rinse until a pale tea colour is obtained, otherwise the flavour will be too harsh. Then sanitise and twice rinse before using with wine.

For larger vessels with wide openings, staves may be practical, in addition to chips and powders. There are even staves available connected end to end in a "Z" folding manner that can be lowered into a vessel, for example a demijohn, and retrieved the same way, tied together by a food-grade plastic filament or stainless steel wire.

If you have a large vessel with a large mouth, like a stainless steel tank or a plastic drum, then oak planks can be used, either singly, or assembled in modules again tied together by plastic filament or stainless steel wire

Dosage rates may vary and suppliers should be consulted, but I have successfully used oak planks at a rate of 0.25 square metres per 100 litres with medium toast French Oak.

Again these should be soaked in boiling or hot water rinsed, sanitised and twice rinsed before using with wine.

Reputable winemaking suppliers like several of our sponsors can advise on types and dosage rates. The choices are generally French or American oak, and light, medium or high toast (and even untoasted).

If the container has a wide enough opening, oak chips can be placed in a mesh bag. Suitable food-grade nylon mesh can be obtained from winery suppliers. This is called "tea-bagging" and makes the removal of the chips much simpler.

The wine should be sampled periodically, at least monthly, and once the desired level of oak character is achieved the wine can be racked off the oak and continue maturation. If after racking further oak treatment is required, the chips can be rinsed and returned to the wine. With chips and planks it may be necessary to scrape off a tartrate build-up to continue effective oak treatment. If there is any chance of contamination during the removal process the oak should be sanitised and twice rinsed before returning it.


Rankine, B. C. (2004) Making Good Wine: A Manual of Winemaking Practice for Australia and New Zealand, Pan Macmillan Australia, Sydney.
Iland, P, Gago, P., Caillard, A. & Dry, P. (2009) A Taste of the World of Wine. Patrick Iland Wine Promotions, Adelaide

Last Updated on Thursday, 18 February 2010 12:30

Oxidation   

Written by Gary Campanella
Friday, 20 November 2009 21:30


1. Introduction

Oxidation occurs whenever a substance combines with Oxygen. We all see the affects of oxidation on foods; cut open an apple, leave it on the bench and it goes brown. That’s because it’s oxidising. Likewise, wine will oxidise when it is exposed to air. An oxidised, brown apple looks unappealing to eat, no longer feels crisp when you bite into it, and certainly lacks a fresh, fruity flavour.

A wine that is slightly oxidised will at first have a hint of a nail polish remover smell (acetaldehyde). If left to oxidise further the wine will develop a nutty, sherry-like smell or a pungent over ripe fruit smell. Just like that cut apple that been left on the bench for too long. If oxidation is allowed to progress, the wine changes colour, looses that lovely fruit aroma and becomes flat tasting. Wine in an advanced state of oxidation will develop a white film on its surface. This is Acetobacter bacteria munching on the alcohol in the wine and turning it into vinegar. Left to go on for too long, the wine will smell and taste and distinctly vinegary. Game over! Tip wine down the drain! Yes, all of it, because it can’t be recovered.

Mercifully, there are proven, simple techniques that do minimise the chance of your wine tasting like a bad sherry or worse. The following comments span the whole of the wine making process and assume you that you are familiar with it and the concepts of pH, SO2 additions and racking.

2. Practices that minimise Oxidation

Each step of the winemaking process presents its own “opportunities” for oxidation mechanisms to come into play and gradually degrade the potential of a wine. Keep the following in mind as your vintage progresses:

a) Make sure that your grapes at the time of crushing are freshly picked, cool, and show no signs of mould. Hot, mouldy grapes are to be avoided as they may be a prime source for bad enzymes that will oxidise grape juice and colour compounds before crushing even starts! The actions of these enzymes (Laccases) cannot be stopped.

b) Add Sulphur Dioxide to your crushed grapes at a rate of 10 to 50 parts per million. Sulphur dioxide is a very effective germicide and antioxidant. It is also an effective inhibitor of the enzymes that form within grapes and cause oxidation during the must phase (Tyrosinases; the same enzymes that cause apples to go brown). Refer to the EDWG article on SO2 treatment.

A more advanced technique is to use a Sulphate calculator to calculate the quantity of potassium metabisulphite required to achieve the appropriate SO2 dosage for your volume of juice and its pH (http://www.winemakermag.com/guide/sulfite). Hint; most sulphate calculators will prompt for a target Molecular SO2 level; use 0.5 ppm for Reds, and 0.8 ppm for whites.

c) Avoid excessive aeration during the fermentation stage. Musts lack the protection of alcohol and colour compounds that provide some buffer against oxidation and therefore are much more susceptible to oxidation than a fully fermented wine.

Oxygen is useful during fermentation of some red wines. More on that in a seperate article.

Fortunately, the high volumes of Carbon Dioxide (CO2) produced during the early phases of primary fermentation provide a barrier to oxygen absorption into a low alcohol must. However, a delayed start to fermentation or a stuck fermentation can present a real risk of oxidising a must.

See the EDWG Summary article on Yeast Fermentation for hints on establishing a healthy fermentation.

d) Maintain wine within appropriate acidity (pH) ranges. Correct pH levels combined with appropriate SO2 levels will provide a high degree of microbial stability and protection against oxidative mechanisms. White wines need to be kept within a pH range of 3.0 to 3.4. Reds within a range of pH range 3.3 to 3.7.

Knowing your wine’s pH is fundamental to decisions around sulphating and acid correction. You can have your wine tested or, you invest in, and learn how to use a good quality pH meter.

There are excellent providers for pH testing services.

See the EDWG Summary article on Acidity and pH for hints on acid adjustment.

Be sure to measure pH after completion of malolactic fermentation and readjust pH if the wine is not within an appropriate range.

e) Maintain correct levels of “free sulphur dioxide” during stabilisation and bulk aging. This is particularly critical for Whites. Again, see the EDWG article on SO2 or use an SO2 calculator to advise you of the correct SO2 levels for the pH and colour of your wine.
f)Have your wine tested for its free level S02 after every second racking and preferably after every racking and top up the SO2 level appropriately. The EDWG "assistance" web section list several excellent providers for pH testing services.

g) Rack wine gently. Don’t splash wine during racking, rather place the racking tub against the side of the receiving container, allowing wine to run along the container walls without splashing.

h) Take extra care with handling white wine. The affects of oxidation are much more readily seen and tasted in a white wine. They also lack the colour compounds of red wines that provide some protection from oxidation, and are therefore much for susceptible to the affects oxidation than red wines. The best practice in handling white wines is to liberally dose containers with an inert gas (generally CO2) before filling with wine, and top up all containers with CO2.

The liberal use of CO2 is a considerable advantage in reducing the risk of oxidation in all types of winemaking.

Refer to the EDWG " Tips and Tricks" article on a very cost effective method of using CO2 during racking white wines. Also refer to the EDWG article on White Wines and Oxidiation.

i) Keep containers topped up and stoppered at all times. Always ensure containers are properly stoppered with rubber, or preferably, silicon bungs fitted with fermentation locks (filled to the correct level with Water/SO2 solution). Fit containers with solid bungs when you are convinced that your wine is no longer “gassing”.

References:
1. Rankine, B. Making Good Wine, 2004
2. Pambianchi, D. Techniques in Home Winemaking, 2008
3. Crowe, A. The Winemakers Answer Book, 2007
4. Iverson, J. Home Winemaking Step by Step, 2002

Last Updated on Tuesday, 29 December 2009 01:11

pH - Related to Acidity   
Written by Stan Gower
Tuesday, 17 November 2009 11:15


If you are picking the grapes yourself the vineyard owner can generally give you a pH value for the general area of the vineyard that you are picking from, so it is a good idea to ask.
1. pH levels for red and white wine
Red juice pH 3.20 to 3.40
Red wine pH 3.45 to 3.65
White juice pH 3.10 to 3.30
White wine pH 3.30 to 3.50
It is best to adjust pH early in the wine making to help other processes.

2. Method of adjusting pH
To REDUCE pH, add tartaric acid.
To INCREASE pH, add Calcium bi-carbonate.

Note: Calcium carbonate is often recommended, but some find that this does not precipitate out properly, leaving a haze. Potassium bicarbonate is usually used by commercial winemakers but sodium bicarbonate (sold as “Baking Soda”, but check the ingredients on the packet),does the job equally well (sodium salts are not allowed commercially because they are not natural in grapes).

3. Amounts to use
UNLESS you have specific chemistry knowledge it is best to send samples to an analysis service to have the pH measured, and to get advice about the amount of chemicals to add to either increase or decrease the pH to within the desired range. (Titratable acidity will also be taken into account in advice given to you.)

You could buy your own pH meter, but the difficult issues there are:

A reliable one is fairly expensive.
It has to be kept calibrated with chemical buffers which need to be fresh.
You then need to have enough chemical understanding to decide what adjustment needs to be made, additions to be made, and how to take into account titratable acidity when adjusting Ph.
Adding Tartaric Acid:
Dissolve in a small amount of water, add to the wine and stir in.

Adding Sodium bi-carbonate:
Have the wine as cold as possible. Dissolve the bi-carbonate of soda in a little water and stir it slowly into the wine. Continue stirring for about 30 minutes. (Some CO2 will be evolved). Rack after a few hours cold.

Note: A lot of CO2 develops when it is first poured into the wine, so there needs to be a reasonable space at the top of the container, otherwise the wine will fizz over the top and make a mess.

It is important, after adding bi-carbonate of Soda to rack the wine after a few hours, cold. The few hours could be 24 if you can keep the wine really cold. The more important thing is that the wine is still cold; otherwise the crystals (of sodium bitartrate) will redissolve. So if you can maintain the same coolish temperature, racking time doesn't matter.

Note: Calcium carbonate is often recommended, but some find that this does not precipitate out properly, leaving a haze. Potassium bicarbonate is usually used by commercial winemakers but sodium bicarbonate (sold as “Baking Soda”, but check the ingredients on the packet),does the job equally well (sodium salts are not allowed commercially because they are not natural in grapes).
Last Updated on Friday, 20 November 2009 02:00

Pros and Cons During White Wine Making   
Written by Reon Vuglar
Friday, 20 November 2009 22:11


1. Introduction
The essence of winemaking whether it be white, red, sparkling or fortified revolves around the decisions we make during the winemaking process, the reasons why we chose to carry out a certain task and the final impact that it has on the wine. This article aims to highlight and identify the different ‘pros and cons’ of winemaking decisions available to the winemaker during production and the potential outcomes of different actions. Before you can make a wine you must decide what outcome you wish to achieve; if you just stomp on some grapes and then wait, yeah, you’ll make wine but does it taste like you wanted it to and give the satisfaction you were looking for? Let’s start at the beginning…

2. The Harvest
The timing of harvest is essential in the moulding of style during winemaking. Light bodied wines without oak or MLF including varieties such as Riesling, Verdelho, Sauvignon Blanc and Gewürztraminer rely heavily on acid to provide weight and structure rather than alcohol. So picking floral whites earlier than full bodied varieties allows the retention of natural acid to provide more delicate structure than added acid. Full bodied varieties can be picked later as increased fruit concentration, alcohol potential, MLF and Oak maturation can be used together to provide extra balance, structure, weight and complexity. The most common white winemaking mistake is trying to make a variety perform above its potential; like trying to create the first barrel fermented Riesling matured on yeast lees for 4 years in new Russian Oak and expecting gob smacking results. The Variety is the noblest part of a wine and it should be held in high stature when deciding on potential style. Slight variations can provide a unique point of difference without detracting from varietal definition. Remember when you try a wine the most obvious attribute should be varietal identification, a 1 year old Riesling should not remind you of a 15 year old Hunter Semillon.

3. The Crush
The goal in white wine production is to maximise flavour and aroma and minimise phenolics and bitterness. As in all grape varieties a lot of the ‘hidden flavour’ is very close to the skins, right next to all the bitter compounds and phenolics. Skin contact during white winemaking is a very risky business as for all the extra flavour you get, along comes a bundle of phenolics. So skin contact increases fruit concentration and aroma but increases potential phenolics. Skin contact is all about balance, do you need it and do the pros outweigh the cons. Again we come back to the essence of winemaking decisions, why have we chosen to carry out a particular task. If you are making a light bodied aromatic wine from Riesling what benefit do you gain if you have 24 hours skin contact to increase fruit aroma but the wine becomes so bitter when you are finished fining you lose all the extra flavour you might have gained and sometimes more. The lesson here is that less handling is better handling. You haven’t got 20 parcels of fruit from around the valley to blend together to get consistency, you have one chance to get it right, so any decision however small it may seem can dramatically effect the potential outcome.

4. Fermentation
Yeast, Yeast, Yeast, beautiful Yeast! It’s available to you as a winemaking tool so USE IT. Even the most remarkable wines in the world are still made with commercial yeast strains.

A better way to increase fruit concentration and balance in white wine is to match appropriate wine yeast with the variety and or style you’re trying to achieve. Unlike skin contact yeast do not increase phenolics and bitterness and if they do you are using the wrong yeast.

Temperature control is the most important factor in producing white wine; a steady controlled fermentation at lower temperatures is the key to retaining varietal definition, aroma and flavour, why let it evaporate into the air when you can work toward keeping it in the wine. If you don’t have access to a jacketed tank or a cool room for barrel fermentations, ice blocks or bottles of frozen water are a good way to help keep fermentation temperatures low. Unhappy yeast gives unhappy flavours so look after your yeast during fermentation as there is no excuse for stuck fermentations. All wine should be made with fermentation aids and yeast nutrients such as Goferm, Fermaid K and DAP. You try running a marathon without water and you’ll know how yeast feels without supplements.

5. Maturation
If wine doesn’t need maturation, bottle it. Again style indicates the need for maturation.

Floral aromatic varieties should be settled, clarified and filtered before sulphur/acid adjustment and bottling. Maturation should be reserved for varieties and styles that will benefit from such processes of oak maturation, MLF, lees contact, batonage, air, and racking, if it doesn’t need it don’t do it. Don’t forget less handling is better handling.

Storage during maturation and post bottling is important to the stability and life of the wine. Constant temperature is more important than low temperature. If you can’t keep wine at 15 degrees (C) as in cellar-like conditions it is better to keep in at a constant 23 degrees (C) under the bed than out in the back shed where the temperature can range from near zero in winter at night to over 30 degrees (C) in summer during the day.

6. Conclusion
Winemaking should be a fun, exciting and enjoyable hobby for the home winemaker, where with good planning and preparation you can achieve the desired results you set out to. Don’t forget to drink it and enjoy it.

Last Updated on Sunday, 03 January 2010 05:30

Racking    

Written by Stan Gower
Wednesday, 30 December 2009 03:12


We said in the main wine making guide, that racking is “simply” syphoning the wine from one contained to another clean and sterilized container. That describes what we actually do; but there is a bit more to understand.

1.Wine needs to be racked three times, around 4 weeks apart.
It may be tempting to ask, “Why can’t I leave the wine to settle for three months, and rack it only once, thus saving work?” The answer is that each movement of wine from one container to another, (provided it is done correctly; see the following notes) helps to stabilize the wine. Note. There are other issues relating to stabilizing wine and these will be covered in a seperate article.

2. It is important to protect the wine from excess oxygen contact during the racking process.
There are two main ways of doing this:

(i) Ensure that the wine contains an adequate level of PMS (providing free sulphur) to protect the wine from oxidation while being transferred from one container to the other.

(ii) Purge the container that will receive the racked wine with an inert gas such as CO2. This displaces all the air/oxygen in the container and so protects the wine from oxidizing. There is no need to purge the sending container with CO2 as it empties, provided the surface of the wine is not agitated.

3. Understanding the make up of the sediment
There can be many deposits in the sediment, such as, particles of grape solids; yeast and bacteria; tartrate crystals; settled finings; metal and protein precipitates, and the like. These different sediments settle at different rates, and they also differ in their ease of being disturbed by the racking process. Some hazy wines may not rack successfully unless they are settled by a fining process first.

4. After siphoning
After siphoning from one container, that container can then be washed with clean water, and be purged with CO2 to become the next receiving container. Check out the EDWG article on an inexpensive, small scale CO2 source

Provided the container is washed and used immediately, it should not need additional sterilization. (It will have been sterilized when first used.)

5. Avoid disturbing the sediment with the racking tube.
It can help to not push the end of the racking tube to the bottom of the sending container, but put the end say 10cm below the surface so that the wine can be sucked into the racking tube to get the siphon going, then “follow down” the lowering surface of the wine with the end of the tube. When the wine has nearly all been transferred, you can tilt the container gently to make the remaining wine deeper. But, be ready to pull the end of the tube out of the last bit of wine as soon as you notice any sediment going along the racking tube.

6. Use CO2 during racking
Although it is more important to purge the receiving container with CO2 when racking white wine, it is a good idea to use CO2 when racking red wines also.

7. Diameter of racking tubes
This needs to be established by experimenting. The tube needs to be big enough to give a satisfactory flow of wine, but if it is too big in diameter, it will be difficult to suck up the wine to get the siphoning going. A bigger tube may also let the wine flow so fast that it will be difficult to follow down the wine surface with the end of the tube. It may also be more difficult to manage getting the most wine out towards the finish while avoiding sucking up some sediment with the wine flow.

8. Storage of racking tubes
It is best to store tubes straight, otherwise it is hard to get them straight when you want to use them.
Check out the EDWG article on storing racking tubes.

Last Updated on Saturday, 02 January 2010 04:28

Red Wine Making Process Chart   
Written by Gary Campanella
Wednesday, 30 December 2009 03:15

 

Last Updated on Thursday, 31 December 2009 07:51

Smelly Wines   
Written by Paul Finn
Friday, 20 November 2009 21:30


Sulphides and thiols are compounds which contain the element sulphur in their structure. The most notorious of these compounds is hydrogen sulphide (H2S) as it gives wine a “rotten egg” odour at very low concentrations (parts per billion, ppb). Other sulphur containing compounds can occur in wine such as; mercaptans, thiols and disulphides. These can give wines odours described as “rubbery, cabbage, garlic and onions”, not particularly pleasant smells in a glass of wine!

Fortunately Dimethyl Sulphide (DMS) is probably one of the better sulphur containing compounds to have in your wine as it often contributes positively to the aroma. At low concentrations it has been described as giving aromas of “quince, truffle and blackcurrant”, all of which sound quite scrumptious! However, at high concentrations DMS can be overpowering and give wine an “asparagus, corn or molasses” aroma. DMS has been recognised as contributing to the aroma and body of bottle aged wines, particularly whites. The aroma threshold for DMS is 18-25 ppb.

How DMS is formed is still not fully understood but it is most likely formed after primary fermentation during ageing on lees. Research has shown that its concentration increases in the bottle over time indicating that there must be precursors present before the wine was bottled.

The most common method of treating a wine with a sulphide aroma is by using copper sulphate. However, DMS does not react with copper. This makes it difficult to remove if it is at levels causing a fault. There is an excellent article in the April 2008 Grapegrower and Winemaker (http://www.winebiz.com.au/gwm/) on the identification and treatment of reductive characters in wine.

Last Updated on Thursday, 07 January 2010 04:59

Sulphur Dioxide  
Written by Stan Gower
Friday, 20 November 2009 21:30

PMS, SO2
PMS has a number of uses in wine making.

1. Used for sterilizing equipment, in a solution, at a concentration equivalent to 2 - 3 teaspoons in 5 litres of clean water. Thoroughly wet already cleaned equipment for at least 5 minutes, and drain, if residual PMS is not a problem; or rinse with clean water to remove all traces of PMS.

2. In the crush, to kill wild yeast, in the concentration equivalent of : -
- 0.535 g PMS / 10 kgs of grapes (1/14 of ¼ oz.)
(ref. p 40 Red NMIT book)

To help preserve the wine in making, and to help prevent oxidation of the wine when it is in contact with air.
Summary of additions, and maintenance levels of SO2, in RED wine.

In the following guide, PMS (SO2) is added 3 times: -
At / before crushing.
After malolactic fermentation has finished before 1st racking.
Immediately after 3rd racking.

 

OPERATION

DETAILS

 

 

 

 

AT CRUSH...

1. The 4 X rule for adding PMS
- *100ppm PMS - gives 50ppm total SO2 - gives 25ppm free SO2
For 10kgs weight of grapes at crush, (This is the capacity of the manual crusher used here.) Call the amount *10 litres of juice for the purpose of calculating 50ppm total SO2; 25ppm free SO2.
(Do NOT use only the projected juice yield which would be around 5 litres from a 10kg crusher full of grapes.)
This is because about 50% of the SO2 will permeate the gross pulp stems and skins, and will be discarded at pressing, and some will be consumed protecting the juice during crushing and de-stemming and pressing, (and, for reference, in the yeast lees at racking.) and all the rest will be bound to aldehydes in the ferment
2. CALCULATION of PMS amount.
Quantity of PMS as for *10 litres juice. =*100ppm PMS 1ppm =1mg per litre (1mg =1/1000 gm) So 100ppm = 100 mgs per 1 litre = 1000 mgs per 10 litres = 1gm
So 1 gm PMS per 10 kgs of grapes at crush gives 50ppm TOTAL SO2, = 25ppm FREE SO2


Weighing with a cheap balance.
NOTE. My balance has a minimum of ¼ oz, and I really do not want to spend money at this stage on a better one. So:-*1gms = 1/30 oz= approx 1/7 of 1/4 oz Or one level teaspoon is about 5 g The reasons for using 25ppm free SO2 at crush. = 100ppm PMS.
(a) that is sufficient to protect the wine from oxidation during crushing then it is protected by CO2 until the wine is pressed and MLF is completed.
(b) because there must be no free SO2 for MLF to happen, and (up to) 25ppm free SO2 is bound during ferment.
IMPORTANT. After adding 25ppm free SO2 at crush, do not add any more PMS until just before the first racking, after yeast ferment, pressing, and MLF are all completed.
 

At 1st RACKING      

1. Send sample to laboratory to test for completion of MLF. (an addition of PMS will stop malolactic fermentation.)

2. then add 60ppm total SO2 = 30ppm free SO2 = 120ppm PMS.

Note. dissolve the measured PMS in water and stir it in.

3. No need to analyse for SO2 at this stage – about half of the addition will be free and will protect your wine at 1st, 2nd, and 3rd racking
See note at 3rd racking below.

 

At 2nd RACKING     

 

 


At 3TH RACKING   

       

No further addition of PMS should be required provided previous additions were made as above.

 

1. There is no need to send a sample to have the SO2 measured before the 3rd racking.

2. It’s a good idea at the third racking to take extra precautions against oxidation by purging the receiving containers with CO2 gas before racking.

3. immediately after 3rd racking send samples for analysis for SO2 to work out the amount of PMS to be added, so that any PMS addition alleviates any oxidation from the racking; and integrates well before bottling.

Note ; Alleviates means that Added SO2 will react with any dissolved oxygen picked up in the racking before it has a chance to oxidise the wine phenolics (turning them brown).
This uses the SO2 as curative as well as a preventative against oxidation.

Removal of excess SO2

If you need to reduce the amount of SO2, (PMS) in the wine, for example, if there is too much to allow malolactic “fermentation” to happen, then SO2 can be reduced by adding hydrogen peroxide in a very carefully controlled amount. So you really need to get advice on how to prepare the amount to be used relative to each size container.
The hydrogen peroxide solution is added drop by drop, at room temperature, directly into the wine, and stirred in thoroughly as each drop or few drops are added. Temperature is not important.

Last Updated on Friday, 18 December 2009 09:44

Tannin Additions   
Written by Bruce Black
Saturday, 17 July 2010 22:50


Tannin additions are typically in the range of 3-6g/100l although you may go as high as 10g/100l, which equates to 30-60 ppm (or a high of 100ppm). Check your selected tannin for the correct dosage rate as it may be different.

Based on the volume of wine to treat and the typical dosage rate you should have a good idea of how much tannin will be needed. Although tannins typically cost about $1/g, this equates to less than 6c/l to treat. This is comparable to oak chips (at say $7 for 500g to treat 100l at 5g/l which would cost 7c/l) but offers much more control over the type of tannin added and the rate it is added. There's also much less risk of over-oaking, which can happen with traditional oak products if they are left in contact with the wine for too long. Finally, by employing bench trials, you know the result of the addition before you commit to treating your whole batch.

To prepare a solution for bench trials dissolve 1g of tannin in 100ml of warm water. While it is preferable to make these measurements carefully so the dosage is accurately known, if this is not possible prepare a large enough batch to treat the entire volume of wine and any error will be allowed for in the bench trial.

It is important to conduct a bench trial as you would for any additive. The effect of the tannin on a wine will vary, and the exact dose can only be determined by tasting at different dosage rates. For the 'typical' tannin addition you would add 0.3 to 0.6 ml of stock solution to a 100ml sample of wine. Once the optimum dose is determined multiple the volume by 10 to get the dosage per litre, which should be between 3.0 and 6.0ml. Multiple this by the volume of the container to get the dosage for each container of wine.

Example.

I have 150 litres of wine to treat, so I calculate my maximum dose is 6g/100l * 150l or 9g. I then buy a 10g or 25g packet (depending on what's available) of my preferred tannin.

I dissolve 1g of tannin in 100ml of water and treat my four 100ml wine samples with 0.3ml, 0.4ml, 0.5ml, and 0.6ml of solution.

I decide that the optimum addition is between the 0.4 and 0.5 samples, so I decide to dose my wine at 4.5ml/l (10 times my test addition). To treat my 150l I will need 4.5*150 or 675ml of stock solution.

I dissolve 6.75g in 675ml of water and add it to my wine. Or in my case, because I'm mean with my supplies, I dissolve 5.75g in 575ml of water, add the 98ml of solution that is left over from my bench trials, and add the 673ml to my wine. (The 150 litres is only approximate, so 673ml is more than accurate enough.)

Last Updated on Saturday, 17 July 2010 22:52

Testing and Adjusting Acid Balance   

Written by George Wright
Saturday, 08 May 2010 11:49


At the March 2010 meeting, life-member of the Guild Karen Coulston demonstrated the importance of achieving a balanced wine, particularly the balance of acid, alcohol and sugar. She mentioned a nifty technique for testing the acid balance. So that we don't forget the suggestion, I have included my notes of how to carry it out, including my interpretation of the calculations sitting behind the technique.

I like it because even amateur winemakers can do this with primitive equipment. You will need a pipette, but the plastic ones are cheap and for our purposes, re-useable.

Step 1: Add 10g tartaric acid to 100ml of wine to be acid- balanced and make it dissolve. (That's 1g/10ml or 100g/L or 0.1g/ml). I will now refer to this as the standard solution

Step 2: Pour 100ml of the wine to be tested into 6 glasses, that's 100ml six times.

Step 3 : Use a pipette to add 1 ml of the standard solution to the first glass, 2 ml to the second glass, 3 ml to the third, 4 ml to the fourth and 5 ml to the fifth. Don't add any standard solution to the sixth because this will be your reference glass of wine that is not changed.

Step 4: Taste each glass to see whether the wine is improved with the addition, compared to reference glass 6. You may find the unadulterated wine tastes best but if it is improved by additions you can select the glass most suitable and determine the amount of tartaric acid to your wine by using the following information:

There are 1000ml in one litre (1L).

The standard solution has 10g acid in 100ml. This is the same concentration as 100g in 1000ml (one litre). In glass 1 we added 1ml so it contained 1 thousandth of this, or 0.1g of acid which we added to 100ml of wine. Therefore we need to add 1g to every litre of wine to balance our wine. If you have made 5L of wine you need to add 5x1g or 5g of acid. Similar reasoning will follow for other selections of test glasses. If you are like me and have difficulties with the calculations, just follow the instructions:

• if glass 1 tastes best, add 1g/L of Tartaric Acid to your wine. For 5L of wine you will add 5g of Tartaric Acid.
• if glass 2 tastes best, add 2g/L of Tartaric Acid to your wine. For 5L of wine you will add 10g of Tartaric Acid.
• if glass 3 tastes best, add 3g/L of Tartaric Acid to your wine. For 5L of wine you will add 15G of Tartaric Acid.
• if glass 4 tastes best, add 4g/L of Tartaric Acid to your wine. For 5L of wine you will add 20g of Tartaric Acid.
• if glass 5 tastes best, add 5g/L of Tartaric Acid to your wine. For 5L of wine you will add 25g of Tartaric Acid.

It's best to take a sample of your wine and dissolve your calculated amount of Tartaric Acid in this before pouring the solution into the bulk wine. You risk having undissolved acid dropping to the bottom of your container if you toss it directly into the wine and try to dissolve it.

Step 5: If glass 6 tasted best, and you added 6g/L of Tartaric Acid to your wine, you've tasted too much. Go to bed.

Last Updated on Saturday, 08 May 2010 11:58

Testing your wine for free SO2  

Written by Bruce Black
Friday, 20 November 2009 21:30

1. Introduction
What follows is a description of how you can set up a very cheap Rankin test for checking the SO2 levels of your wines. Be aware that many people that use this test initially report that they cannot get it to work and they aren’t getting any readings from their wines. After a bit of checking they usually find the test works fine, but their wines haven’t been getting any SO2 protection.

Because this is a kit built from improvised equipment I’ve spent a bit of time describing each piece, so you can decide what you have available that will work best for you. The initial idea came from the www.winepress.us Internet forum, but I’ve modified their process slightly as a result of reading other write-ups.

2. The Equipment
a small aquarium pump. The recommended size is 1 litre/min, but anything about this size will do. I had one already, but a cheap one should be $10-$15. I’ve also found that hydroponics shops often sell aquarium equipment cheaper than aquarium shops.
A narrow jar to hold about 100ml. We’ll be adding about 50ml of liquid, so it needs to be narrow enough for a good depth of bubbles from the pump, but not so small that the bubbles overflow. If you can get one a 100ml test tube is perfect.
A 2-hole stopper to fit the jar. The stopper needs to fit the jar well – no air can escape around it. The holes must fit the tubing (described next) tightly for the same reason. I got a solid bung and drilled two holes just big enough to force the tubing through. It isn’t pretty, but it works well.
Tubing. Aquarium airline is recommended, but the 3mm black irrigation tubing from Bunnings that is used for dripper systems would work just as well. The clear aquarium tube quickly discolours in red wine, but that doesn’t affect the test.
Bubblers. I used drippers or micro-sprays from Bunnings. They screw or press straight into the end of both aquarium and irrigation tubing. Anything that creates a small hole for air bubbles will work.
Small reactor jar. This needs to be smaller than the jar described above. It only holds 15ml of liquid and the bubbler must be fully submerged so the SO2 liberated from the wine is completely captured. You also need to see the colour change in the indicator, so clear or white is a good choice. I use a small white pill jar, but a 50ml test-tube would be perfect.
Graduated pipettes or burettes – I have 1ml, 10ml, and 25ml pipettes, but only 10ml or similar is absolutely necessary, and even then a small medicine syringe would work. If using a burette you would probably choose 25ml, but you would also need a pipette or syringe to measure your wine sample.

3. Chemicals
All of these can be obtained from your regular wine equipment supplier. If yours doesn’t have something, try one of the other Guild sponsors.

Standardised 0.1N Sodium Hydroxide. You should already have this if you test for Titratable Acidity. You will only use a few mls per test
3% Hydrogen Peroxide. You use 5ml per test, and it will react with the SO2 in your wine to create sulphuric acid. This needs to be stored in the fridge.
25% Phosphoric Acid. You will use 15ml per test to acidify your wine, which liberates the SO2 from the wine.
Mixed (or two-part) indicator. You only use a couple of drops per test, so a 15ml bottle will be plenty. I know it’s a strange name, but that’s what it’s called.
Distilled water.
Dilute Acid – either 0.1N hydrochloric acid or you can make some by adding a small pinch of tartaric acid dissolved in a few ml of water

4. Equipment Set-up

 

Push one airline through a hole in your stopper and adjust the length until it is just above the bottom of the larger jar/test-tube when you insert the stopper firmly.

Add a bubbler to the bottom of the airline. Connect the other end to the aquarium pump. This line should be reasonable long to give you a bit of flexibility.

Push another piece of airline through the other hole in the stopper so it just comes out into the jar/test-tube. On the other, free end add another bubbler. If you are using aquarium tubing it should be flexibly enough to bend over into the small jar/test-tube.

If you are using irrigation tubing you may have to add a couple of elbows

5. Testing
1. Mix up your hydrogen peroxide and indicator.
You need 15ml of 1% hydrogen peroxide per test, so depending on how many tests you are doing measure out that many multiples (plus one spare) of 5ml into a beaker. So if I was testing 3 wine samples I would measure (3+1)*5ml = 20ml into a beaker. Then add twice as much distilled water (40ml in my example) to give a 1% solution. If the concentration of your original hydrogen peroxide is not 3% just adjust the volumes so you end up with 15ml of 1% per test plus a bit extra. Eg. If you start with 2%, take 7.5ml and add 7.5ml of water, if you have 5% take 3ml and add2. Prepare your 0.01N Sodium Hydroxide.

 

 

The exact amount you need to make up will depend on the number of tests you are running, but you will need 5ml of 0.01N sodium hydroxide for every 50ppm SO2 you expect in your wine.

So for 3 tests at about 50ppm, you will need 15ml.

I’d make up 20ml or 30ml, which will only require 2 0r 3 ml of your 0.1N standard solution

 

For every 10ml of 0.01N solution you estimate you will require, take 1ml of 0.1N Sodium Hydroxide and add 9ml of distilled water. These two items must be measured accurately as this becomes your new standard for titrating the SO2.
Add this 0.01N Sodium Hydroxide to you diluted Hydrogen Peroxide one drop at a time until the indicator returns to the Aqua/Green colour again. This is the starting point for your titration and the point I find hardest to get to. The colour change is subtle but clear, but until I’ve seen it change from one to the other I’m never sure if I’m looking at blue/grey or aqua/green. That is part of the reason I mix this standard in one go for all tests.
3. Prepare your wine sample.
Measure out 32ml exactly of your wine sample and add it to the larger jar. Add 15ml of phosphoric acid and seal the jar tightly with the stopper, making sure the bubbler is below the surface of the wine.
4. Aerate the sample.
Measure 15 ml of the dilute hydrogen peroxide into your small contained and insert the free end of the airline with the bubbler below the surface. I use a clothes peg to make sure it stays there. Turn on the aquarium pump after the bubbler is set up and let it run for about 15 minutes. I’ve tried longer, but provided you have vigorous bubbling, 15 minutes seems to extract all the SO2 from the wine.
5. Titrate the resulting solution.
After 15 minutes turn off the aquarium pump and remove the hydrogen peroxide jar from the airline. The solution should have returned to the blue/gray colour. Titrate this with the 0.01N sodium hydroxide you have prepared until the indicator just turns back to the aqua/green colour. The ppm of SO2 in your wine is the number of mls of 0.01N sodium hydroxide multiplied by 10. ie. If it takes 3.6ml to turn the indicator aqua/green, then you have 36ppm free SO2 in your wine.
6. Discard the wine and used solution and repeat steps 3 – 5 for your other samples.
7. Sources of Error
While some measurements make no difference to the final result, some are critical, and the following list indicates which are the major sources of error in this process.
The volume of wine. The amount of SO2 liberated is directly proportional to the volume of wine.
The concentration of the original 0.1 N sodium hydroxide solution. This deteriorates with time and should be verified or replaced regularly.
The amount of sodium hydroxide used in the 1:10 dilution.
The amount of distilled water used in the 1:10 dilution.
The volume of 0.01 N sodium hydroxide used in the titration.
The other items – the volumes of phosphoric acid, hydrogen peroxide, and the water used to dilute the hydrogen peroxide have no impact on the result provided they are near the numbers suggested.

Another possible error is due to the carry over of volatile acids from the wine to the hydrogen peroxide which would give an artificially high result. Actual results suggest that this is not normally a factor, but the test cannot be used for total SO2 measurements which involves heating the wine.

7. Safety
All of the chemicals involved in this test are corrosive and quite dangerous if the contact the skin or eyes, or are ingested. For this reason, if you are using pipettes rather than syringes or burettes, a pipette filler is strongly recommended.

References
http://www.monashscientific.com.au/ProcedureSO2Determination.htm
http://www.winepress.us/forums/index.php?showtopic=25460 12ml of water.
The exact concentration isn’t critical, but about 1% works.

Then add about 2 drops of indicator per test (15ml). The indicator will either turn a blue/grey colour or an aqua/green colour. If it is blue/grey add some 0.1N sodium hydroxide, one drop at a time until it turns at aqua/green colour. Then add 1 drop of dilute acid to just return the indicator to blue/grey.

White Wine Making Process Chart   
Written by Gary Campanella
Friday, 20 November 2009 21:30
 

Last Updated on Thursday, 31 December 2009 07:52

White Winemaking and Oxidation  
Written by George Wright
Friday, 20 November 2009 21:30

Reproduced by permission of George Wright from his web site:
http://www.members.westnet.com.au/georgewri/Wine/Wine.htm

George Wright is a member and past President of the EDWG.

It’s relatively easy to produce a drinkable red wine. Just squash a red grape and it will start fermenting. You will have trouble stopping it turning into an alcoholic beverage. A white grape will also ferment and the product is also likely to be alcoholic but is less likely to be drinkable.

With whites, there can be all sorts of quality control issues associated with fermentation: temperatures and yeast types, vessels and handling techniques, additions and timing of activities. Anything can go ugly at any stage and often will, but the biggest ugly pill for amateurs is oxidation. Oxidation generally results from the exposure of the juice/wine to oxygen in the air or from the addition of inappropriate chemicals. It results in an unpleasant off-taste in the wine, excess yellow or brown colours and a lack of fresh, fruity flavours and zest in the mouth. Exposure to oxygen in the air is the more common problem and wines with high pH (low acidity) are most susceptible.

Oxidation can be augmented by high grape temperatures which encourage berry splitting and juicing, physical damage by birds, mechanical harvesting, wasps, foxes or kangaroos. Thin skinned varieties such as Sav Blanc or Semillon and tight bunches and excessive ripeness can increase juicing and the potential for oxidation.

The problem is complex because when the white grapes are crushed the resultant juice becomes oxidised immediately. You can see the juice flowing from the press that is brown in colour, and the longer you press, the browner the juice. It can bring on a panic attack. Calm down…the oxidative processes taking place at this time are likely to be reversed as the juice ferments into wine. In fact, some winemakers actively promote oxidation at this time by agitating the juice from healthy grapes with oxygen (swishing their fingers through the juice) to ensure that the easily oxidised chemicals in the wine are converted at this stage rather than in the bottle at a later stage of maturation.

Oxidation increases with exposure to air and to higher temperatures. If the grapes are affected by fungus attack (e.g. Botrytis cinerea) the enzyme laccase may appear causing berry splitting and the resultant juice may be more resistant to sulphur dioxide additions used to reduce oxidation. Sulphur dioxide addition will assist in reducing oxidation. This can be added to the grapes in the picking bins, at the crush or into the crushed juice and skins at the crush. These additions also control wild yeast ferments if this is desired. Additions generally vary from nothing to around 100 parts per million SO2, the latter being used for diseased grapes.

Once juice ferments into wine, it is very susceptible to oxidation. Every exposure of the wine to oxygen is likely to result in yellowing or browning and loss of flavours. Activities such as racking and bottling can easily destroy the characteristics of the wine. There is a paradox in that cool wine can contain more oxygen than warm wine but oxygenation occurs faster at higher temperatures. If you treat the wine when cool and expose it to air it will take up oxygen which will then react when the wine warms up. You need a blanket of an inert gas such as CO2 over the wine every time you expose it to the air.

Previously, Ascorbic Acid (Vitamin C) was recommended as an additive to white wines to increase the anti-oxidant ability of SO2, to improve juice colour and enhance fruit flavours. It is readily oxidised and although it enhances the antioxidant effects of SO2 it cannot be used as a substitute. When Ascorbic Acid reacts with oxygen it produces Hydrogen Peroxide, a very vigorous oxidising agent. SO2 must be present to mop up the peroxide as it is produced. The product of oxidised Ascorbic Acid (Dehydroscorbic Acid) readily reacts to produce yellow colours in the wine. Ascorbic Acid lacks the ability of SO2 to also inhibit yeast and bacterial growth. If a bottle of wine is stored for a lengthy period the SO2 will become fixed and unavailable to protect the wine and the Ascorbic Acid will then oxidise, giving detrimental impacts on the wine. It’s probably useful only for wine that will be drunk shortly after production (Sav Blanc, unwooded chardonnay, etc). Its beneficial effects are now regarded to be transitory and its use is now generally discouraged. If you want to experiment in using it to give a fruity lift to a white wine, do so and enjoy the product, but drink it early.

Here are my Rules of Thumb:

If you are serious about making a good white wine, invest in the hire of a Carbon Dioxide cylinder and cover the wine with gas every time you expose it to air. Scout around for the best price. I have found our sponsors (see below) lease cylinders at a fraction of the price of the big suppliers of CO2. Give them a ring.
Use Sulphur Dioxide as an anti-oxidant: You may want to use it before the primary ferment but you certainly should use it afterwards. The higher the pH, the more sulphur dioxide you will need. Add too much and your wine will stink. Add to little and you may rather pour it down the sink than drink it. If you have decided to make white wines you will need an accurate pH measurement which will assist you to determine the amount of SO2 you need to protect the wine during storage before and after bottling. This can be obtained from a laboratory analysis or from a pH meter. If you are not prepared to do this, don’t bother attempting to make white wine, because you are likely to produce an inferior product. There is a greater chance of success with red wines without this equipment, but it is still recommended. Many members have a pH meter…ask for assistance.
If you know the pH, the amount of SO2 to add can be calculated by reference to good winemaking books. Ask an experienced winemaker if you want assistance. The WEB has ‘Sulphite Calculators’ to assist and these are available if you do a search (e.g. http://www.filedudes.com)
If you are paranoid about oxidation the chances are that you will be able to manage the other more subtle nuances applicable to making a good white wine….the control of ferment temperature, the use of oak, the timing of bottling, the use of lees…..but if you can’t control oxidation, the other issues are probably irrelevant, despite your best intentions.
When adding Ascorbic Acid, don’t add until after you have added Sulphur Dioxide and be prepared to drink the wine early.
Last Updated on Saturday, 19 December 2009 03:09

Yeast Fermentation  
Written by Gary Campanella
Friday, 20 November 2009 21:30


1. Introduction
Fermentation of the must (grape skins and juice) is the first and most important step of the vinification process. In addition to your choice of grape variety and its quality, the final qualities of your wine are influenced by your ability to control key parts of the winemaking process. Such factors as temperature, sugar concentration, pH, acidity, SO2 level, the rate of fermentation, tannin level, colour, and many other factors combine to make your wine either superb, average or less than desirable. Your choice of yeast, and then how you start and manage your fermentation, are critical to ensure it completes without problems.

Yeast is more than just something that causes fermentation; it can also affect the look, taste and smell of your wine.

Fermentation can start on its own without the aid of cultured yeast. There is an abundance of wild yeast in the air and on grape skins that will greedily consume the wonderful, nutritious sugars on your prized grapes. Wild yeast fermentation is a risky business for most beginning winemakers. Managed incorrectly it can result in off odours and tastes in your wine through microbial spoilage. It is highly recommend that you start your winemaking using good quality, freshly purchased yeast.

2. Yeast Selection
There are a very wide range of yeasts available from manufacturers such as Lallemand (Lalvin), Scott Labs, White Labs, Wyeast and others. However, the selection available for home winemaking is very limited because most are packaged in quantities that are more suited to commercial volumes. Lalvin have a small range of yeasts that are sold in sizes that are more appropriate for home winemakers. Many of the home winemaking and brewing suppliers will also sell generic “Red” and White” wine yeasts that are suitable to start with.

Standard dose = 0.2 gm of yeast to 1 litre of wine

3. Yeast Nutrients
Yeast is a living organism requiring food. So called micro and macro nutrients help the yeast to complete a healthy, trouble free fermentation.

Supplementing the grape juice/must with a good mix of vitamins and nitrogen sources should be part of what you do to ensure sound fermentation. Add your nutrients to the juice/must BEFORE you inoculate with your chosen yeast.

Diammonium Phosphate (DAP) is the most common and cheapest nutrient and will suffice most of the time. Use at a rate of 0.2 grams per litre of juice/must.

Balanced yeast foods are generally a better choice since they contain a mixture of DAP, Vitamins and other organic nutrients. These are generally used at a rate of 0.5 to 1 gram per litre of juice/must. Check the dosage recommended by the manufacturer for the yeast food that you purchase.

No matter what you decide to use, it is important that you calculate and measure your additions carefully, then mix with enough juice to ensure it is fully dissolved. Mix this solution well into the juice/must to be fermented.

You will optimise the uptake of added nutrients by staggering your additions. There are many suggestions on the timing of nutrient additions. A good place to start is by adding one-third of your total nutrient addition before you add your yeast to the must. Add a further 1/3 when fermentation starts, Add the remaining 1/3 when the Specific Gravity of the must (Brix/Baume) has reduced by 1/3.

4. Preparing the Yeast
Correct preparation of your yeast will go a long way towards avoiding fermentation problems. Although it may work, it is not recommended to just sprinkle dried yeast over the juice/must and hope for the best!

One method of starting yeast fermentation is to follow this procedure.

Re-hydrate dried yeast by sprinkling yeast over 1/2 cup of warm (37.5 C) water and leave for about 10 minutes. Do this in a wide, flat dish to ensure that all of the dried yeast is evenly hydrated. Otherwise you will end up with messy clumps of yeast.
Add a pinch of DAP
Mix one cup of fresh grape juice and one cup of water. This will form the starter base for up to 40 L of must. For more than 40 L of must, double or triple volume of juice and water.
Mix yeast cup with diluted juice in either a carafe or jar.
Add a pinch of DAP to the above starter solution
Plug with a cheese cloth and set in a warm place. It is important to complete the above dilution within 15 to 30 minutes of hydrating the yeast.
Starter solution should be actively fermenting within an hour or two
Inoculate must when starter solution is actively fermenting before inoculating must

5. Ensuring a trouble free fermentation
Ensure the yeast you choose can ferment the level of sugar present in your must. High sugar musts can be difficult for some yeast strains.
Each yeast strain has its ideal temperature range, so check this with the yeast manufacture’s data sheet. Most commercial stains are content to ferment between 16 to 35 degrees C.
Acclimatise the started yeast before you add to your juice. Your fermentation can be off to bad start if there is a difference of more than 10 degrees C. Acclimatise by Slowly (over a period of 5 minutes) combining an equal amount of the must (juice) to be fermented with the yeast suspension. This will help the yeast adjust to the different temperature of the must (juice) and will help avoid thermal shock. This temperation step may need repeating for very low temperature must (juice). Each atemperation step should last about 15-20 minutes.
Yeast inoculation should not occur within 30 minutes of adding sulphur to the juice/must. Keep sulphur additions below 50 parts per million at the juice/must stage.
Be sure that you are using a yeast that will cope with the sugar level present in your juice
Ensure that you have an appropriate level of nutrients in your must
Monitor fermentation temperature and ensure it is kept below 35 C. for red wines, and below 27 C for white wines. These are absolute maximums to keep below, not necessarily desirable maximum fermentation temperatures for red and white wines.
Use only sound, mould-free fruit otherwise you risk having competition from too many other microbes.
Do not use yeast that is beyond its expiry date, or 12 months after opening.

References:
Iverson, J. Home Winemaking Step by Step, 2002
Rankine, B. Making Good Wine, 2004
Pambianchi, D. Techniques in Home Winemaking, 2008
Crowe, A. The Winemakers Answer Book, 2007
Scott Labs, The Fermentation Handbook, 2006 and 2008...

Last Updated on Sunday, 03 January 2010 12:39

                  

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