A beer maker is using yeast to make his favorite brew. how does yeast produce ethanol? through the reduction of acetaldehyde, derived from pyruvate through the oxidation of acetaldehyde, derived from pyruvate through the direct reduction of pyruvate, similar to lactic acid fermentation directly from the reduction of glucose through the reduction of lactic acid

In brewing, yeast is used for the fermentation step, which is the conversion of sugars into carbon dioxide gas (CO2) and ethyl alcohols (etOH). Yeast cells require complex enzymes for the fermentation of glucose based sugars into alcohols and carbon dioxide. The process involves both aerobic phases where yeast proliferate on a log scale followed by an anaerobic phase where oxygen is deprived and C02 maintains the gaseous environment. The second phase also clarifies the product allowing for the conversion of less savory alcohols into more palatable alcohols like ethyl alcohol.