What is Fermentation?

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The Basics

Fermentation is a chemical change brought on by the action of microscopic yeast, molds and bacteria. The souring of milk, the rising of dough and the conversion of sugar to alcohol are all examples of fermentation. Of course the conversion of sugar to alcohol is what we are interested in so that is what we will be concentrating on.

Alcohol is produced when yeast enzymes break up sugar into roughly equal parts of alcohol and carbon dioxide gas. Everyone may be familiar with bakers yeast but most yeast occur wild in nature and grow on plants and animals where they are dispersed through the air and water. Yeast spores are everywhere and if they get a chance they will gladly ferment your grape juice or malt. The problem with this is that there are thousands of strains of wild yeast and most of them are not suitable for fermenting alcohol. Most wild yeast will give your beer or wine strange off-tastes and a lot of them are not very tolerable of alcohol which means you will end up with a partly fermented, low alcoholic, sweet beverage. That is why brewers and wine makers use yeast that is specifically cultured for the fermentation of alcoholic beverages.

Modern fermentation practices have all but eliminated the problems that plagued wine and beer makers for thousands of years. Our better understanding of yeast and bacteria have resulted in techniques that keep out unwanted microorganisms which can cause spoilage.

How to make quality beer and wine.

  1. Use clean equipment in good condition. Dirt harbours bacteria and bacteria grows rapidly in wine and beer which can cause spoilage. Old discolored or scratched plastic equipment is impossible to clean and will cause problems.

  2. Sanitize all equipment after cleaning using a specialized sanitizer supplied by home brew and wine shops.

  3. Use a tight-fitting lid on all fermenting buckets and an air lock. Exposure to air can introduce wild yeast and bacteria. This is particularly important during the first 24 to 48 hours before your yeast has had a chance to start working.

  4. Use only high-quality and fresh ingredients.

  5. Use at least 10 grams of fresh yeast per five gallon batch of beer.

  6. Follow a good set of instructions and don't listen to your next door neighbor "who has been brewing for years". I have seen too much beer and wine spoiled by well intentioned advice from neighbors and coworkers. If you have a question contact your wine or beer supply store. They deal with hundreds of queries and have the resources to answer your questions.

Follow these guidelines and you are well on your way to making commercial quality wine and beer.

Are you ready for the next step? Then you should read our step by step instructions for making beer and wine.