Its all in the yeast

Yeast

Yeast has been used for thousands of years to brew beer, but it wasn’t until the mid 1850’s when French scientist Louis Pasteur discovered that yeast converted sugars to produce alcohol, before then brewers must have just thought the production of alcohol was magic. The yeast used in beer really changes the taste and the length the beer takes to brew. There are thousands of strains and the big breweries are very protective of their yeast cultures, with many cultivating them for hundreds of years. As there is natural yeast in the air it is very easy to contaminate your yeast with other strains. There are two main types of brewers yeast, top fermenting and bottom fermenting- the difference is where the yeast ferments, bottom fermenting tends to ferment at the bottom of the barrel were the other at the top making a foamy top on the wort. Bottom fermenters are usually used to produce lager style beers while many of the darker or higher alcohol beers tend to use the top fermenters which usually brew the beer a bit sweeter or fruitier