Final answer:
To ferment starch into alcohol, the process begins with converting starch into fermentable sugars, followed by the addition of yeast or bacteria to perform fermentation, where sugars are turned into ethanol and carbon dioxide. Specialty yeast strains can be used to influence the flavor and consistency of the final beverage.
Step-by-step explanation:
Stages of Alcoholic Fermentation
The process of fermenting starch from grain, tubers, or fruit into alcoholic beverages involves several key steps. Initially, the starch must be converted into sugars, which can be fermented by yeast or other microorganisms. This conversion is typically achieved through a process known as malting in grains, where enzymes break down the starches into fermentable sugars.
The next phase is the fermentation process itself. Here, yeast or bacteria are added to the sugary solution, which then converts the sugars into ethanol and carbon dioxide under anaerobic conditions. This occurs in two main steps: the first generates CO2 and acetaldehyde, while the second step involves the oxidation of NADH to NAD+ and the reduction of acetaldehyde to ethanol. The carbon dioxide produced can cause bread dough to rise or can be released in the case of alcoholic beverages.
Today, it is possible to purchase specific strains of yeast that are well-suited for particular types of alcoholic beverages, enhancing the consistency and flavor profile of the final product. When producing beer, wine, or other alcoholic drinks, the selected yeast strains can have a significant influence on the outcome.