Fermentation of Cider
Fermentation is the name given to the conversion by yeast of carbohydrates into
alcohols and it 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!
As the yeast gets to work on 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.
Normally we purchase dried yeast that has been specially selected for its good brewing qualities. However, at a pinch you can use bread making yeast too. 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 brewers yeast, keep it stored in the refrigerator.