Wine Fermentation

Wine FermentationOrdinarily the first stage of fermentation is carried out in a bucket or fermenting bin. It is possible to kick start your yeast reproductive cycle and boost numbers with a yeast starter and that’s something we’ll look at in more depth soon. The other way is to re hydrate the yeast by adding it to a small quantity of luke warm water, the instructions to do this are almost always on the packet so check that out.

Once the yeast is prepared it is “pitched” into the must (the fruit pulp and sugar) it then begins to reproduce and grow by using the sugar as fuel and after a short lag time which may be up to 24 hours it will begin to foam and bubble with activity. This is what we call primary fermentation and is the first real step towards your alcoholic wine.

This primary fermentation doesn’t last long, around a week or two and at this point we separate the liquids from the pulped fruit and allow the yeast to continue with their activity which will be a lot more sedate now. This secondary fermentation is usually carried out in a carboy or demijohn which protects the wine from oxygen and wild yeast whilst the wine clears.

Transferring to Secondary

After the initial burst of fermentation or the “primary fermentation” has finished we need to move the wine into a demijohn or carboy. There are still processes occurring and the yeast will still be working but in a slower and less visible manner. What usually occurs is the wine is separated from the pulp of the fruit or flowers by straining and the secondary fermentation continues in the demijohn with an airlock fitted.

Straining can be as simple or hard as you make it, depending on the flavour of the wine or the fruit, flower or flavouring used you may be able to strain the wine with something such as a sieve or a fine straining bag may be necessary. The goal is of course to remove as much of the pulp or debris as possible. In some cases where a fruit has been pulped finely it may be a good idea to strain the wine twice, firstly with a something with fairly large holes to remove the bulk of the pulp then through a finer strainer to remove the smaller particles.

What’s Going On During Secondary Fermentation

The yeast will at this point have consumed most of the available sugar and nutrients available to them and will be now cleaning up and evening out the flavour of your wine. During the first stages of fermentation yeast creates compounds that although necessary for their growth and function aren’t that great when you taste them. Allowing the yeast this secondary phase of fermentation gives them the chance to removes these undesirable compounds and flavours and gives us a better wine.

There is also the fact that the wine will at this point be very cloudy and there is no way you should be bottling it at this point. This time in the demijohn will allow it to slowly clear.

Getting Prepped

Wine AdditivesMost people will want to dive straight into making their first ever wine and I remember I was very much the same. But when I made my first blackberry wine it was made more difficult purely because I hadn’t  prepared everything properly. I didn’t have the right straining bag for instance and no yeast nutrient. At the time this didn’t bother me too much and I made a passable wine; passable not great. Get prepared from day one and you’ll make great wines.

First of all you’ll need to gather some essential bits and pieces, I talked about basic equipment  here. This stuff really is the bare minimum and shouldn’t set you back too much. Once you have it you’ll only need to make a few gallons of wine to return your investment. I can assure you it will be well worth it.

Nutrients, Acids and Other Additives

Just like in your kitchen where your cupboards are stocked with staples,. for the country winemaker apart from the actual ingredients you need to make the wine there is also a similar set of staples that you should always have to hand. When you have these things you’ll be ready to make any wine as soon as the ingredients are available, so what are they?

Yeast Nutrient: Yeast is a living organism that when added to a must (unfermented wine) will look to grow and reproduce. Having a lot of healthy yeast is essential to winemaking because they are the organisms that turn all the sugars available into alcohol. To grow and reproduce they feed on the sugar which will be in plentiful supply of course but also need other organic compounds to thrive. These organic compounds aren’t always present in enough quantity in fruit and especially flowers and vegetables. To get around this problem and ensure an adequate amount of healthy yeast are present we use a nutrient.

Yeast nutrients are readily available from your home brew store or online and contain various compounds to ensure your yeast can grow and reproduce at a fast rate and will ensure your wine doesn’t stop fermenting half way through.

Campden Tablets: When making wines with wild ingredients like fruit, flowers or vegetables there will be a whole variety of bacteria and wild yeasts present. Whilst they aren’t harmful and won’t make you sick they can spoil your wine turning it to vinegar which is of course unpleasant to drink. To prevent this a campden tablet can be added to the pulped fruit and will prevent those spoilage bacteria and wild yeasts from ruining your wine.

Once the campden tablet is added a compound called sodium metabisulphate is introduced to the ingredients which sanitises the must and destroys any wild yeast but has no adverse effects on the flavour of the wine. The must is left to stand for 24 hours then a wine yeast is added to get fermentation off to a flying start.

Acid Blend: A key factor to making a great wine is starting off with the right level of acidity in your must. Acid is needed to keep balance in the wine and also to provide the ideal conditions for the yeast. Yeast thrive in slightly acidic conditions and may be sluggish or slow to ferment if the level of acid isn’t quite right. Grapes are ideal for making wine as they have the natural levels of acid needed already in the fruit, other fruits usually have too little acid so wine makers can employ an acid blend to make up for this.

Acid blends are so called because they are made up of usually 3 different acids in varying proportions, the acids are citric, malic and tartaric which are all natural acid found in fruit. A lot of wine makers use lemon juice in their recipes to provide a boost in citric acid. Using acid blends however is a more convenient and efficient option.

Pectic Enzyme: Some fruits have high levels of pectin, a compound that allows people to turn fruit to jam. The problem with pectin in wine is that it can leave a wine permanently cloudy, whilst you can still drink the wine and it will be perfectly palatable adding one tablet will ensure this doesn’t happen and show your wine off at its best. Adding pectic enzyme to the fruit at the extraction stage will stop any pectin haze and also help extract more body and colour from the fruit you are using to give you a better wine.

Gather Your Supplies

If you have all of these things then all you’ll need to do when you get the urge to make a wine is get the flavour component (fruit, flower or vegetable), sugar and yeast and you’re ready to go. Meanwhile though have these things ready and you’ll never be stuck when it comes to getting a wine started.

Racking and Clearing A Wine

Clearing and RackingIt is usual to move a wine from a fermenting bucket into a demijohn because at this point in the fermentation process there is a lot less activity from the yeast, they are producing less CO2 which forms a protective barrier on top of the wine. Moving the wine into a demi john allows us to attach a bung and airlock. The airlock is a device filled with water, it allows carbon dioxide to escape from the carboy or demijohn but will not allow air in. This prevents the wine from becoming oxidised and developing unwanted flavours.

The wine may sit in a carboy or demijohn for a number of months as the yeast finish their tasks and slowly begin to fall to the bottom of the demijohn. It is this point we rack the wine to a new clean container for further clearing.

To make a good wine at home it needs to not only taste good but also look good. Give a guest or friend a glass of cloudy wine and they will have already made assumptions about it before it even touches their lips. This is why we need to take the time to allow the wine to clear and removing the wine from any debris or sediment after fermentation has finished.

Racking A Wine

When a wine is fermenting there will be a lot of yeast in suspension as well as other debris from the fruit as well as insoluble salts and compounds. It is this debris that gives our wine a cloudy appearance during fermentation.

As fermentation slows and comes to an end those yeast cells will begin to die and slowly sink to the bottom of the demijohn or carboy. Over the period of a month or two a layer of these particles and dead yeast cells will cover the bottom of the demijohn. When we see this happen we need to move the wine off the sediment, using a syphon to avoid disturbing the sediment, into a clean sanitised demijohn or carboy to continue clearing.

This racking process is usually done twice during the time the wine is in a demijohn but there are no hard and fast rules. Generally after fermentation is finished you should see a deposit of sediment (called lees) within a couple of weeks and the wine will be visibly clearer then during the height of fermentation. This is a good time to rack the wine for the first time, the second time will usually be a month to 45 days later, when another deposit is left and the wine is pretty much clear.

Every Wine Is Different

I have just said it’s usual to rack twice before bottling however some wines may be different and take longer to clear for one reason or another as a general rule rack the wine every 2 – 3 months as long as there is a fresh layer of sediment. Leave the wine on the lees for longer than 3 months and you risk the wine developing off flavours. If you see a layer of sediment then syphon the wine off it.

Achieving a Clear Wine

Once a wine has completely cleared and all signs of fermentation are long gone then it’s time to bottle the wine. At this point some wine makers stabilise the wine using potassium sorbate which will stop any kind of fermentation once bottled. It’s not strictly necessary but is something we’ll look at in the future.

Usually a clear wine will be achieved after a few months and racking it a few times into clean demijohns or carboys. On some occasions however you may have a wine that is stubborn to clear so you may choose to use a fining agent to speed the process along. A fining agent is a product designed to clear a wine, some wine makers use them routinely but they aren’t necessary on most occasions. There are various products available from your home brew supplier, if you do choose to use a fining agent just follow the instruction on the pack. I will write in further detail on different types of fining here soon.

Then, it’s on to bottling.