In order to make alcohol, you generally need starch as a starting material. Starch is a complex carbohydrate that is found in various plant sources such as grains, tubers, and roots. It is composed of long chains of glucose molecules, which are not directly fermentable by yeast.
When making alcohol from grains, such as barley or corn, the first step is to convert the starch into fermentable sugars. This process is known as starch hydrolysis or saccharification. It involves breaking down the starch molecules into smaller sugar molecules that yeast can readily consume and convert into alcohol.
There are several methods to convert starch into fermentable sugars. One common method is through the use of enzymes, specifically amylases. Amylases are naturally occurring enzymes that break down starch into simpler sugars. They can be derived from various sources, including malted grains or commercial enzyme preparations.
In brewing beer, for example, malted barley is used as the primary source of starch. During the malting process, the barley grains are soaked in water and allowed to germinate. This activates enzymes present in the barley, which convert the starches into sugars. The barley is then kilned to stop the germination process and preserve the enzymes. These malted barley grains, known as malt, are crushed and added to hot water in a process called mashing. The enzymes in the malt break down the starches into fermentable sugars, creating a sweet liquid known as wort. The wort is then cooled and yeast is added for fermentation.
In the case of other starch sources like potatoes or cassava, the starch needs to be extracted and then treated with enzymes or heat to convert it into fermentable sugars. This can be done through mashing or cooking the starch with water and enzymes, or by adding malted grains to provide the necessary enzymes.
It is worth mentioning that there are alternative feedstocks for alcohol production that do not rely on starch. For instance, sugar-based feedstocks like cane sugar, beet sugar, molasses, or fruit juices can be directly fermented by yeast without the need for starch conversion. These feedstocks already contain simple sugars that are readily fermentable.
While there are exceptions when using sugar-based feedstocks, if you are starting with a grain or other starch-containing material, you will need to convert the starch into fermentable sugars before yeast can begin fermentation and produce alcohol. This conversion can be achieved through enzymatic processes, typically involving malted grains or commercial enzyme preparations.