Fermentation of Cider
Fermentation is the name given to the conversion by yeast of carbohydrates (sugar) into alcohol. Fermentation is central to the cider making process.
Yeast is a very simple living organism which consumes carbohydrates to get its energy. Alcohol is actually just a waste product that the yeast creates. Effectively, cider is yeast pee! Mmm.. tasty!
As the yeast gets to work on the sugars in the apple juice, you will notice bubbles. Lots of bubbles. They will form a scum and then a foam and may well spill over the sides of the bucket and make a mess on the floor. This is a cause for celebration because it means the yeast is active and cider is being made.
Brewer’s yeast tolerates up to about 5% alcohol. Beyond this alcohol level the yeast can’t survive and fermentation stops. Wine yeast on the other hand tolerates up to about 12% alcohol. Cider yeast sits somewhere in the middle and is generally sold in 5g sachets.
Normally we purchase this dried yeast that has been specially selected for its good brewing qualities (Youngs is the only manufacturer in my local homebrew shop). However, at a pinch you could use bread making yeast instead. It is basically the same stuff, but will impart a slightly stronger yeasty flavour to your cider which you may not like. Yeast for cider making is available all over the place and of course all over the web too.
Although the yeast comes in dried form, it does have a limited shelf life. If you buy a large tub of yeast, best to keep it stored in the refrigerator.
So, you have had apple juice fermenting away for a few days and then the bubbles stop. That is the end of part one… Yes, the home brewing process is in two parts.
- Part 1 – the foamy bubbly messy bucket stage
(Usually 24-48 hours)
- Part 2 – the slow gentle blip, blip in a demijohn stage
(Usually 2-3 weeks)
The process of transfering your brew to a demijohn deserves a page to itself. We call this process racking off.