You can find everything you need for wine making these days with a wide variety of wine equipment offered at hardware stores and home brewing retailers. Much of the necessary equipment is dealt with below, but firstly let’s look at what it can be made of. Most important, whatever equipment you are using, remember sterilization is the name of the game.
Glass, wood, metals and plastics are all used in wine making, but certain types should be avoided. Colored plastics have dyes that can taint the flavor of wine, so you should steer clear of these. Undyed polythene is fine for short term use but should not be used for storage vessels. Polythene is slightly porous allowing alcohol to diffuse out resulting, in time, in a weaker wine. At the same time, air slowly seeps in causing over oxidation and browning. polypropylene however, as long as it has no added dyes, is fine to use for storage. Iron and copper should not be used as they are soluble in fruit acids and will badly affect the taste.
Galvanised items are even worse and can even be poisonous. Wood can have many uses in winemaking, however, thoroughly clean wood used to make wine. Glass is universally accepted as the best storage material for the home winemaker. Make sure that all glass vessels are free from cracks and chips. Again, whatever the material, the key word is sterilization.
Types of Equipment
Made of glass or plastic, this S-shaped tube fits through a cork or bung into the top of the fermentation jar. Carbon dioxide is allowed to bubble out whilst airborne spoiling organisms are prevented from getting in. The fluid in the bend should be a 1% solution of sulphur dioxide. This should be changed monthly.
Barrels and Casks
Barrels and casks are traditional vessels for fermenting and storing wine. It is argued that the flavour from the wood can improve a wine as well as its semi-porous nature helping in aging. Old barrels that have been lying around in the garden should be avoided like the plague. Any smell in the empty barrel is likely to be transfered to the wine. Test the sweetness of a barrel by giving the outside a good slap whilst sniffing at the plughole. Alternatively fill the barrel with fresh water and leave for 24 hours. Now taste the water and see what flavours it has absorbed. To clean out barrels before use, one third fill will boiling water, put in a two meter length of chain and roll around for 15 to 20 minutes. If nothing else this will get you fit. Rinse and fill with a 2% solution of sulphur dioxide. Leave for 24 hours and rinse well. When using barrels as storage always fill completely leaving as little air in the top as is possible.
Any wine bottles can be used but it is traditional to use clear bottles for white or rose wine and coloured bottles for red wine. Use a bottle brush to scrub inside and remember to sterilize.
A hand held corking tool is used to force corks into the necks of bottles. The cork is pushed down the tapered tube by a plunger that is struck with a hammer or mallet. Moisten the corks before use to lubricate them.
As mentioned before, barrels are perfectly usable as are certain food quality plastics. However the most popular material for the home winemaker is glass. The 1 gallon Demi-john is most commonly used by the beginner though 5 gallon or 2½ gallon Carboys are also popular.
By rights wine filters should not be necessary, but they can help with certain clearing problems. An inexpensive piece of equipment, they are lined with disposable filter papers that can remove particles that are suspended in the wine. It should be remembered that a filter will only remove particles and will be ineffective in clearing a haze. An alternative to buying a filter is to fold a filter paper into a cone and use it to line a funnel.
A basic but very useful piece of equipment. Don’t forget to sterilize inside and out.
The Hydrometer is used to calculate the alcohol content of the wine
Whilst far from being a necessary piece of equipment, electric juicers can be extremely useful with hard fruits. Don’t bother buying one but if you already have one don’t be afraid to use it.
Much like juicers, Fruit Presses are far from obligatory but can be useful. Available in all sizes they are relatively inexpensive but if you fancy yourself as a bit of a D.I.Y. you could build your own.
A length of plastic tubing used for transfering the wine between containers whilst racking or bottling. The main advantage is that the liquid can be syphoned off without disturbing any sediment.
There are two types of sterilization practical for the home winemaker. They are through using heat or chemicals. Before sterilizing, wash the equipment with detergent and rinse well.
The heating method can be either wet (boiling water) or dry (in the oven). Remember that some glass items will crack if subjected to a sudden thermal shock. Some plastic items may not withstand any considerable heat.
Preheat the oven to 300ºf (150ºc) and leave the item in for one hour. Smaller items can be wrapped in paper but do not leave unattended in case of fire. Allow to cool slowly without opening oven door. Plug bottles and jars with cotton wool to prevent the ingress of contaminated air as they cool.
The problem with this method is that water cools much more quickly than you would think. To be effective the water MUST be hotter that 180ºf. Items need to be immersed for 20 mins, so keep that kettle on.
A good method for smaller items. Cook for 20 mins at 15 p.s.i.
Whatever the chemical, use boiled and cooled water for rinsing. Tap water can contain bacteria that will affect the taste of the finished product.
Available as a powder or in the very haddy Campden tablet form. 2½oz per gallon of water will give a 1% solution of sulphur dioxide, the active agent. Allow the equipment to be fully immersed for one hour before rinsing well.
Milton and similar brands used as directed for baby products give good results. Rinse well to prevent affecting the flavour.
Many specialized brands of sterilizing powders are available on the market today. Use as directed and remember to rinse well.
There are a number of ways of extracting the Juice or Flavour from the fruit being used. The most suitable method will depend on the type of fruit being used.
Roughly chop the fruit up and boil it with the water in a large saucepan. Then simmer for 30 minutes or until the flavors from the fruit have come out into the water. The benefits of this method are that it is fast and easy and no other sterilization of the fruit is needed. The main disadvantage is that Pectin in the fruit will cloud the wine unless a retarding enzyme is used. The boiling can also be done in a Pressure Cooker.
This a rather more lengthy method but gives excellent results. Place the fruit in a large saucepan or bowl and pour on 4 pints of boiled and cooled water. Crush 1 Campden tablet or 1 gramme of Sodium Metabisulphite in a teacup of warm water till completely dissolved and mix in with the fruit. Cover with a clean teatowel and leave stadding for 4 or 5 days for the flavour to infuse into the water. Stir well after the second day. Boil another 4 pints of water and dissolve into it the required amount of sugar. Stir this into the bulk. Allow the mixture to cool to room temperature and spinkle on a teaspoon of yeast. Cover and allow to stand for another 4 days. The mixture will now start to ferment and a foam will form on the surface. Skim off any scum and syphon into a fermentation jar to continue the ferment.
So far we have dealt with fermenting the fruit on pulp where the raw fruit is crushed, mashed or sliced into the water to extract its flavor. An alternative with some ingredients is to squeeze the pure juice out of the fruit using a press. This is not possible with many softer fruits such as strawberries or plums as they will just result in a pulp. However this is a suitable method for hard fruits such as apples and some soft fruits such as grapes. When using a press chop the fruit up and put into a fine muzlin cloth to prevent small patricles of crushed fruit getting into the juice and also for easy removal of the remaining solids or pomice. An alternative is to use a juice extractor or liquidiser. This will give a liquid with fruit particles in suspension but the solids will seperate out if left for 24 hours. Add a campden tablet to prevent bacterial attack whilst standing. The juice obtained in this way can be fermented as it is but may need extending with water to correct the level of acidity.
Fruits naturally contain sugars in varying degrees. The sugar content will vary not only in different fruits but will also be determined by the growing conditions of the fruit. As a rule the more sunshine, the higher the sugar content. Grapes have a particularly high sugar content and their juice can be fermented to a moderately strong wine without the addition of any sugar at all. However, it will generally be necessary to add sugar. The amount of sugar you need to add will depend on a the amount of natural sugar present in the fruit as well as the desired alcohol level and sweetness of the finished wine. A common question here is how to balance the alcohol and sweetness levels when both appear to be directly related to the amount of sugar. That is, how do you stop the fermentation to get a sweet, low alcohol wine? This is dealt with in the Fermentation section. Most amateur wine makers will never use anything other than household granulated sugar. Whilst this is perfectly suitable for the job, sugar comes in a variety of forms, some of which are suitable and some of which are not. Let’s look at them.
Often blended with beet sugar, this is the household granulated sugar that is most widely used. Chemically it is 99.9% sucrose which is inverted by the acid in the fruit prior to fermentation. (see invert sugar below).
This is for the serious enthusiast. When cane sugar is used, the acid environment of the fruit juice allows an enzyme in the yeast called sucrase (or invertase) to convert the sucrose into the simpler sugars glucose (dextrose) and laevulose (fructose) which are then fermented. Although this process takes place almost straight away, it can be argued that it is better to use sugar that is already inverted. In practise this gives a more even fermentation and thus an arguably better quality finished wine. The amateur, however, need not worry about this as the difference is likely to be negligible. Invert sugar is available to buy, though more costly than the household variety. On the other hand it is possible to invert some household sugar before adding it.
- Put 8 lb of sugar in a sauce pan with 2 pt water and ½ oz citric acid.
- Bring slowly to the boil, stiring frequently and boil for 30 mins.
- Stir in another 2 pt boiling water and allow to cool.
This can now be stored in jars. When using allow 1¼ pints in place of each lb of household sugar. Remember that each 4 pints will already contain ¼ oz of citric acid.
Honey is mostly invert sugar and thus ideal for fermenting. It can be fermented without the addition of any fruit though they are usually added to give flavor. Drinks made this way are called meads and metheglins.
Pure glucose ferments easily as will be seen from above but only has about half the sweetness of cane sugar.
This can be used in specialist instances where an underlying flavour of rum is desired, but on the whole is not suitable.
None of these are suitable for wine making.
Yeasts are a family of microscopic, single celled fungi.
There are many varieties of Yeast, some of which are beneficial and many which will spoil the wine. Natural airborne yeasts are around us all the time, hence the need for vigillance with sterilization. The desired action of the Yeast is to excrete enzymes that convert the Sugar into Ethyl Alcohol and CO2. This is dealt with in more depth in the Fermentation section. Given that there are many varieties of Yeast, there are a number available to the winemaker. It is possible to use the naturally occuring yeasts such as are found in the Bloom that forms on grape skins. However, the dangers of spoiling agents being present make it more sensible for the amateur to use a refined variety. Yeasts also have varying degrees of tollerence to alcohol. When the alcohol content reaches a certain level it will kill the Yeast and the fermentation will end. Strains with a high tollerance to alcohol are generally prefered in winemaking. Specialist Yeasts are available to match almost any type of wine or fruit ingredient. The keen amateur, however, need not worry about using anything other than a general pupose Wine Yeast. Here again there are choices. Nothing comes easy. Wine Yeast can be bought as Powder, Tablets or a Liquid Culture. The Liquid Culture is preferable but the dried powder or tablets are more available and easier to use for the amateur. The powder can be sprinkled onto the surface of the must and will indeed give a passeble wine. However, whilst in powder form the yeast is inactive and will take some time to start working. It is better to culture the yeast into a nucleus or starter before adding it to the must. Instructions for creating a yeast nucleus are given below. Used in this way the yeast will be active when added to the must. This will result in a more even fermentation and will yield better results.
Preparing a Yeast Nucleus
Add a teaspoon of sugar to ¼ pint of water and boil.
Cool and add a few drops of lemon juice and a tablespoon of sterilized orange juice.
Put it into a half pint bottle, sprinkle on a teaspoon of yeast and fit an airlock.
Store in a warm place. The activity of the yeast will soon be seen.
When the yeast is needed shake the bottle and pour off most of the liquid into the must.
You can now top it up with water, sugar and juice as before.
This way the nucleus can be kept almost indefinitely but it is recommended to start afresh each year because of the increased risk of contamination.
Fermentation in wine is the process whereby the yeast converts the sugar into Carbon Dioxide and Ethyl Alcohol.
An interesting fact is that the atomic weights of the two products are almost the same, so as you see the carbon dioxide bubbling off you can have the satisfaction of knowing that the same mass of alcohol is being produced in your wine. This also gives us a chemical means of calculating the alcohol content of the wine. Getting away from the chemistry for a while, in practice there appear to be two stages to the fermentation though there is no distinct dividing line. Firstly comes the primary or Aerobic (with air) fermentation. This is a vigorous action often resulting in a foam on the surface. It lasts for about a week and is usually conducted in an open container covered with a clean tea towel known as the ‘primary fermentation vessel’. Next comes the secondary or Anaerobic (without air) fermentation. This is a much more gentle process that lasts for a number of months. This should take place in a fermentation jar fitted with an airlock. The occasional bubbling of the airlock is often all to show that things are still happening. In fact there is a third possible stage to the fermentation that occurs at a much later stage. This is know as the Malo-Lactic Fermentation and is dealt with later. Let’s look at the chemistry in a bit more depth.
The actual fermentation of the sugar is done not by the yeast directly but by enzymes that are secreted by the yeast as it multiplies. There are five enzymes involved and their actions are listed below:
- Firstly Hexakinase splits the Glucose or Fructose, which are hexose sugars with six corbon atoms, into simpler triose sugars with only three carbon atoms.
- Secondly Aldolase converts the triose sugar into Glyceric Acid and Glycerol. The glycerol stays as it is and gives a smooth finish to the wine.
- Next the glyceric acid is broken down by Enolase into Pyruvic Acid.
- Carboxylase now converts the pyruvic acid into Acetalhehyde and the Carbon Dioxide that bubbles away.
- The final stage is the action of Zymase in reducing the acetaldehyde into Ethyl Alcohol.
Given that the yeast excretes enzymes that cause the fermentation, there are a couple of factors to take into account to ensure it goes successfully. Firstly there is heat. The temperature range to aim for is 65° to 75°F. Below this range the yeast will become inactive and cease to create the enzymes. Should this be the case it is easy to remedy by moving it to a warmer place. At the other end of the range, the yeast will be prevented from producing enzymes at 82°F but it should be remembered that the action of the enzymes produces heat and the temperature of the ferment can be somewhat higher than the room temperature. Another danger is that with excess heat in the Zymase stage of the fermentation an oxidation reaction can result in the production of acetic acid or vinegar. For these reasons the ferment should be kept within the range given.
An important point here is that ultra-violet light will inhibit the activity of the yeast and in extreme circumstances can kill it. So avoid storing the ferment in direct sunlight.
The second consideration is the chemical balance of the ferment. In order to multiply the yeast needs to feed. All of the necessary nutrients will usually be present in a fruit pulp but if a pure juice or a substance other than a fresh fruit is to be fermented it may be necessary to add a particular chemical or a general yeast nutrient.
Given time, as the alcohol level gets high enough or as all the sugar is used up, the yeast will die and the wine will become stable. However it is not unknown for wine to start fermenting again after months in the bottle. A change in weather conditions and thus the temperature can be the cause of this as well as chemical changes within the wine. You may also want a low alcohol, sweet wine. We need to find a way to stop the fermentation from continuing. This is called stabilizing and can be achieved by adding 2 campden tablets or 1 gramme of potassium sorbate per gallon prior to bottling. An alternative is to fortify using a spirit such as brandy. If the alcohol content of the wine is known is is relatively simple to calculate the amount of spirit needed to bring it to a level that is considered safe, but for the beginner adding 20-25% of the volume of wine in spirit should do the trick. It is also possible to use heat as a stabilizer in a process called flash pasteurisation, but this is really beyond the amateur.
This is the possible third stage of the the fermentation process as mentioned earlier. It occurs some time after the fermentation propper has ended, even a year after bottling. Whilst a continuation of the fermentation in the bottle is to be avoided as it can result in blown bottles, a malo-lactic fermentation is to be welcomed. A bacteria in the wine called lactobacilli will convert mallic acid into lactic acid. A small amout of carbon dioxide will be released which in extreme circumstances can result in a semi-sparkling wine but the main result lies in the fact that lactic acid has about half the acidity of malic acid. This gives a somewhat less acidic wine with a much cleaner, fresher flavour. A malo-lactic fermentation can be encouraged by agitating the bottles and storing for a while in a warmer place but generally one can just be hopeful that it might happen. If the wine has been artificially stabilized there will be no chance of this fermentation and it should also be remembered that the lowering of the acidity of the wine can make it more susceptible to other bacterial attack.
Racking & Bottling
At first the must will be a murky, cloudy mix but as the fermentation progresses the liquid will start to clear and a thick deposit of yeast and solids will form on the bottom. Racking is the process whereby the liquid is syphoned off the deposit or ‘lees’ into a clean fermentation jar. There is no benefit at all in racking the wine during the fermentation unless it has stuck. The introduction of air into the wine can sometimes get things going again and this method prevents the deposit being stirred back into the wine. Racking at the end of the fermentation however has a couple of benefits. Firstly, leaving the it to stand on the lees when fermentation has ended will impart a nasty flavor of autolysed yeast into the wine. By racking it you can leave the wine for some time to ensure the fermentation has ended without risking spoiling your wine in this way. Secondly, repeated racking of the wine can do a lot towards helping it to clear before resorting to a fining agent. When racking always make sure that the receiving fermentation jar has been thoroughly sterilized. After racking top the new jar up with a syrup made from boiled and cooled water and sugar mixed to the same proportions as in the wine. This will allow the minimum contact with air in the jar and will reduce any oxidation. Sometime, despite continued racking, the wine will still have a haze. We will now have to resort to other methods to get the crystal clear results we are looking for.
Like all other equipment used, all bottles must be thoroughly sterilized. Use a bottle brush to clean the insides. Ensure that they are free from chips and cracks that can harbour bacteria and may cause the bottle to break. The type of bottle you use is of course entirely up to you but traditionally red wines are kept in dark brown or green bottles, rose wine in clear bottles and white wine in light green or clear bottles. The wine can be transfered into the bottles using the syphon but push the end of the tube right into the bottle to minimise the contact with the air. Fill the bottle up so that the minimum amount of air will be left in when the cork is inserted. Cork the bottles as soon as possible after filling to reduce the risk of contamination. Corks are the traditional means of sealing the bottle but plastic stoppers and screw tops are also available. Whichever you use don’t forget to sterilize them. Corks can be soaked for 2 hours in a 1% sulphite solution. You can add a little glycerine to act as a lubricant and prevent hardening. Once soaked dry thoroughly with vigorous shaking. You can now label your wine and store it in a cool place ready for when you want it.
The first thing to say is that the best ingredient for clearing a wine is time. Most wines will clear of their own accord if left long enough. Moving to a cool place after fermentation has ended will help this to happen. This natural clearing can sometimes take up to 6 or even 12 months but is worth the wait. The beginner will often reach for the jar of finings as a matter of course, not realizing that over or incorrect use of finings will itself cause a haze. Sometimes, however, the wine will not clear on its own and we have to look at other ways of helping it clear. There are two methods available to the amateur, Filtering and Fining.
There are a variety of wine filters available on the market. They are relatively inexpensive and easy to use. The wine is passed through a replaceable filter paper either by gravity or, in the more expensive models, by suction. An alternative to buying a filter is to fold a filter paper into a cone and put it in a large funnel. Selection of the correct grade of filter paper is important. Too coarse a paper will allow the offending particles through, too fine a paper will get clogged up. There are disadvantages with this method. Firstly, many hazes are caused by microscopic particles that will pass through the paper, and secondly the introduction of air during the process can cause oxidation problems.
This is the process of adding a substance to the wine to enable the particles causing the haze to be deposited at the bottom. Before we look at the substances that can be used we need to understand what is causing the haze. The particles in the haze have a tiny electrical charge. As the charge on each particle is the same polarity they repel each other so are not able to gather together and sink to the bottom. By adding a fining agent with the oposite charge the charges are cancelled out and the particles clump together. Gravity then makes them sink to the bottom as a residue leaving the wine clear. It can be seen then that using a fining agent with the same charge will only make things worse. Also, using too much finings will result in a haze of particles with the oposite charge to that we started with. A method to determine which polarity of finings to use and in what quantity is in the Tests and Additives section. Once the type and quantity of finings to use has been established it should be mixed thoroughly with a small quantity of the wine before mixing into the bulk. Most haze problems encountered by the amateur are caused by positively charged colloid particles. This can be treated with Bentonite. Negatively charged hazes are dealt with by Gelatine, Isinglass and Egg white or shell. You may hear of other substances being used, such as dried blood and carbon, but for one reason or another these are not suitable for the amateur.
I have mentioned Hygiene often before and make no apology for doing so again, such is its importance. Numerous agents may be introduced into your wine at any stage that can ruin the whole batch. I urge you to follow the guidelines set out in the Sterilization section at all times.
Bacteria and fruit flies getting into the wine are the obvious causes of spoilage, however there are other substances that may already be present in the fruit or even the water that can adversely effect the finished product. Listed below alphabetically are the spoiling agents that you are likely to have to consider. Some of them are necessary for the fermentation process but will cause harm if the concentration is too high. If you are uncertain, the Tests and Additives section shows methods to determine the presence and level of many of these factors.
Microscopic bacteria are found all around us. The home winemaker has to sterilize all equipment but should also be aware of the bacteria on the fruit being used. Sulphiting or boiling will help destroy this. Acidity level in a wine is important. Acid will prevent the action of spoiling bacteria but too much will give an acid taste. You should aim for somewhere within in the range of pH 3.5 to 3.0. Citric acid, malic acid, tartaric acid or, more simply, lemon juice can be used to achieve this. One well known effect is that of the baceria Acetobacter. This causes the ethyl alcohol to combine with oxygen to form acetaldehyde and then again to form acetic acid, or vinegar.
The fermentation needs to be conducted within a range of temperatures. (66° to 82°F, 18° to 28°C) Below this range the yeast will become inactive. Moving to a warmer site will reactivate it but left alone for a prolonged period this will taint the flavour of the wine. Temperatures above this range will kill the yeast. Again leaving the wine standing on this dead yeast will in time effect the flavour.
Moulds are a microscopic fungus that can be present on the fruit or can be airborne. Many need a free supply of air to flourish but for some varieties the small amount of air left in a filled bottle will be sufficient. This shows the importance not only of sterilising the equipment but also of not leaving the wine exposed to the air for longer than necessary. Mould growth is characterised by its cotton-wool like appearance. The felty skin with grey-white flecks known as ‘flowers of wine’ is a mould growth. You may be lucky. If the mould was airborne it may only have attacked the surface of the wine and the bulk underneath can be carefully syphoned off. However, moulds can introduce mycotoxins into the wine and a batch attacked by mould should really be thrown away.
Pectin is a complex polysaccharide. It is the substance that causes jams to gel and is present to a greater or lesser extent in all fruit juices. Yeast contains an enzyme called pactolase that breaks down the pectin but it is frequently present in too great a quantity for the yeast to deal with. If left untreated it can cause fruit and yeast particles to be held in suspension in the wine causing a haze. This is a particular problem if the boiling method is used as the heat is a great catalyst for the action of the pectin. A pectic enzyme can be added to the wine to deal with the problem. This will break the pectin down into structures that are completely soluble or are dropped as a deposit.
Starch is present in root vegetables and unripe apples. If not dealt with it will produce a haze much like pectin. Starch can be broken down to a form that can be fermented through a process called acid hydrolysis where acid is heated and it is heated. Much like pectin it can also be dealt with by the addition of an enzyme. Iodine is used to test for the presence of starch.
Ultra violet light will reduce the activity of the yeast and can kill it in extreme circumstances. Avoid leaving the wine in direct sunlight.
The vinegar fly warrants particular mention. This tiny fly is attracted to fruit juices like a magnet and carries the bacteria that will turn your wine to vinegar.
Whilst yeast forms the basis of winemaking it should be noted that there are many strains of yeast. Not all of these are beneficial. Wild airborne yeasts, if allowed to get into your wine, can spoil it in much the same way as a mould. These yeasts are a considerable risk if you try to use the natural yeasts on the fruit rather than a refined variety.
TESTS AND ADDITIVES
We are going to tackle this backwards. The first section will look at the various substances that you can add to your wine and what it does. Then we shall look at the various means of testing your wine for things like alcohol content, acidity etc.
Ammonium sulphate can provide a source of nitrogen which helps the yeast cells to multiply. Not generally necessary but can be missing from some fruits. A general yeast nutrient will contain this or a substitute.
Bentonite is a negatively charged earth that can be used as a fining agent. This is covered in the ‘Clearing‘ section and ‘Tests‘ below.
These are ordinary fruit preserving tablets. They provide an easily manageable source of the sterilising agent sodium metabisulphite. The active ingrenient is sulphur dioxide.
Using extra fruit can give a fuller flavour to the wine. This can lead however to the acidity level being too high. Medicinal chalk or ground cuttlefish will crystalise the acid which will settle with the chalk. The juice can now be strained off. Use ¼ oz per gallon of juice.
Citric acid is most commonly used to balance the acidity of the juice prior to fermentation. Available in powered form. For details of acidity measurement see below.
Fresh or dried egg whites can be used as a fining agent. They carry a positive charge. Fresh egg whites are only suitable for very large quantities and over fining is easily done. The powdered form is more easily managed.
Gelatine is obtained from bones and is possibly the most commonly used positivelly charged fining agent. Its use is discussed in the ‘Clearing‘ section below. See also ‘Tests‘ below.
This is a positivelly charged fining agent derived from the air sacs of the sturgeon fish. Its action is similar to that of gelatine.
Adding the juice of a couple of lemons to each gallon is the easiest way for the amateur to ensure that the acid level of the juice is high enough without having to take measurements.
Used to break down pectin which, if present to high enough a degree, will make your wine cloudy. There are a variety of brands available and each suggest use a different stages of the winemaking process, so follow what is said on the packet.
½ gm of ammonium phosphate per gallon shaken into the wine can be the cure of a stuck fermentation once all other considerations have been taken into account. It also provides the yeast with nitrogen so can be used in place of ammonium sulphate if a general yeast nutrient is not used.
This is used to stabilize a wine after fermentation to ensure that further fermentation does not take place in the bottle. 1 gm of potassium sorbate per gallon of wine will do the trick.
Sodium or Potassium Metabisulphite
With an active ingredient of sulphur dioxide this is a readilly available sterilising agent. Available in powder or tablet form.
Tannins are a group of substances present to a greater or lesser degree in all plants. They provide that astringent quality that dries the palatte. they also contribute towards the keeping quality of the wine. Tannin can be added but only if deficcient. A good source of tannin is cold tea.
Thiamine (vitamin B1) can increase the activity of the yeast. Again this is often present in a general yeast nutrient.
Like all living organisms yeasts need to eat to grow and multiply. Some of the necessary minerals such as ammonium salts have already been mentioned. A general yeast nutrient will contain all that is needed. It will often not be necessary as all that the yeast needs is present in the fruit juice but it is often advisable to use a nutrient anyway as a precaution. This is particularly so with root and flower wines.
Testing for Alcohol Content
The main piece of equipment used to measure the alcohol content of wine is the Hydrometer. This is a graduated stick of glass or plastic with a bubble on the bottom that floats in the wine. The disolved sugar in the wine prior to fermentation will give it a greater density than when the sugar has been converted to alcohol. Therefore the hydrometer will float at a higher level. As the sugar is used up the density will reduce and the hydrometer will sink lower in the wine. When all of the sugar is gone the wine will approach the density of water. The density of the wine compared to that of water is called the Specific Gravity (or s.g.). The s.g. of water is 1.000 Note that it is possible for the final s.g. of a very dry wine to drop below 1.000 as the alcohol it contains is even less dense than water.
The hydrometer is graduated and the s.g. can be read from the scale. Take the reading level with the bottom of the meniscus or curve of the liquid. By measuring the s.g. before and after fermentation you can calculate the alcohol content of the wine. Firstly find the degrees of gravity lost by deducting the final s.g from the initial s.g. Ignore the decimal point. Next you will need to select a factor from the table below. The factor is determined by the original s.g.
Finally you need to devide the degrees of gravity lost by the factor to find the percentage of alcohol by volume. As an example; original s.g is 1.110, final s.g. is 1.004 degrees lost (ignoring decimal) = 1110 – 1004 = 106 percentage alcohol by volume = 106/6.96 = 15.23%
Now we come across another problem. The method above is fine if all of the sugar is added at the beginning of the fermentation, but how do we calculate the alcohol content if we add more sugar later on? What we have to do is find out what the original s.g. would have been had we added all the sugar at the start. To get at this we need to know a few facts.
1. Weight = Volume x s.g.
2. Volume displaced by 1 lb of sugar = 10 fl.oz
3. One gallon (imperial) = 160 fl.oz
Now we add together the weights and the volumes for each addition and then calculate back to find what the original s.g. would have been. This can best be shown with an example.
Suppose we start with a gallon of juice that has an s.g. of 1.080 and later in the fermentation we add ½ lb of sugar.
For the original juice, weight = volume x s.g. = 160 fl.oz x 1.080 = 172.8 oz
For the added sugar, weight = 8 oz and volume displaced = 5 fl.oz
Therefore total weight = 172.8 + 8 = 180.8 oz
and total volume = 160 + 5(fact 2 above) = 165 fl.oz
Now we reverse the formula, s.g. = weight devided by volume
So original s.g. would have been 180.8 / 165 = 1.096
Now we have the calculated original gravity we can proceed as if the sugar was all added at the beginning.
Testing for Acidity
Having a sufficient level of acidity is important for the fermentation, flavour and keeping qualities of your wine. On the other hand too high a concentration of acidity will also adversely affect the taste. There are two methods of testing the acidity level.
Narrow Range pH Indicator Papers
These are slips of reactive paper similar to the litmus paper that you may remember from your school days but somewhat more sensitive. They are dipped into a sample of your juice or wine and will change colour. This can then be compared with the colour chart provided to show the pH level. A pH level of between 3 and 3.5 is what we are aiming for.
This is a more accurate method but the equipment can be expensive and it can be argued that such accuracy is unnecessary for the amateur. The equipment needed can be bought individually but these days titration kits are available that contain all you need. The method involves mixing a sample of your juice or wine with distilled water and an indicator, either litmus paper or phenolphthalein. Sodium or potassium hydroxide is then dripped into it from a burette until reaction is observed. Comparing the amount of hydroxide used to a chart provided will give you the percentage of total acidity present. These instructions are somewhat sketchy as they will vary between kits.
Testing for Pectin
It has already been mentioned that pectin can be the cause of hazes in wine. This can easily be tested for using methylated spirit. Put a teaspoon of the wine in a small glass beaker and add four teaspoons of methylated spirit. Mix well. A gelatinous haze that precipitates will indicate the presence of pectin and can be treated by the addition of an enzyme. There will usually be a slight haze caused by the presence of gums but this should not be confused with the more obvious indication of pectin.
Testing for Starch
Starch will generally be broken down in the fermentation process but if present in too high a proportion can cause a haze in the finished wine. To test for starch put a teaspoon of the suspect wine in a small test tube and add two drops of tincture of iodine. Shake well and examine the colour. A blue colour indicates the presence of starch. This can be treated by adding the enzyme amylase. Use 5 gms per gallon of wine.
Testing for Correct Fining
As mentioned in the Clearing section, a haze may be caused by either positively or negatively charged particles being held in suspension. This is a test to find which type and what quantity of fining agent to use. For this test you will need a graduated pipette and 6 test tubes or small, clear bottles. Most problems are caused by positivelly charged protein matter so we will start with a negatively charged fining such as bentonite. Prepare a 1% solution of bentonite by mixing 1 gm in 100 cc of warm water. Measure 100 cc of the wine into each of the test tubes. To these add 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 cc of the bentonite solution.Shake them well and leave over night. Next day, see which has given the clearest result. If none are clear the do the same process but using a positively charged fining like gelatine. Having found which gives the best result we can calculate how much we need to add to fine the whole batch of wine. Suppose the batch with 2 cc added was best. This represents 0.02 gm of fining per 100 cc of wine. One gallon is about 4500 cc so the amount of fining needed per gallon is 0.02 x 4500/100 = 0.9 gm.
After all that wine making, you deserve a drink. Good thing you know how to make it yourself now. All you need now are some refined wine bottle stoppers, wine glasses and decanters, and some other wine accessories to reward yourself for your new hobby.