What are the differences between lactic acid and alcoholic fermentation?

Lactic acid fermentation produces lactic acid, while alcoholic fermentation produces ethanol and carbon dioxide.

Lactic acid fermentation and alcoholic fermentation are two types of anaerobic respiration, which occur in the absence of oxygen. They are both processes that cells use to extract energy from glucose when oxygen is not available, but they differ in the products they produce and the organisms that carry them out.

Lactic acid fermentation is a metabolic process by which glucose and other six-carbon sugars are converted into cellular energy and the metabolite lactate. It is an anaerobic fermentation reaction that occurs in some bacteria and animal cells, such as muscle cells. When your muscles are working hard, they may lack enough oxygen to carry out the normal cellular respiration process. In such cases, they switch to lactic acid fermentation, which allows them to continue to generate ATP, the cell's energy currency. The downside is that lactic acid builds up in the muscles, causing muscle fatigue and a burning sensation.

On the other hand, alcoholic fermentation is a biological process which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by-products. It is carried out by yeasts and some types of bacteria. Alcoholic fermentation is commonly used in the production of alcoholic beverages and bread. The carbon dioxide produced during fermentation is what causes bread to rise, and the ethanol gives alcoholic beverages their alcohol content.

In terms of chemical reactions, lactic acid fermentation can be summarised as glucose becoming 2 lactic acid molecules, while alcoholic fermentation can be summarised as glucose becoming 2 ethanol molecules and 2 carbon dioxide molecules.

IB Biology Tutor Summary: Lactic acid fermentation, occurring in some bacteria and muscle cells, turns glucose into lactate, providing energy when oxygen is low, but can cause muscle fatigue. Alcoholic fermentation, carried out by yeasts and some bacteria, turns sugars into energy, ethanol, and carbon dioxide, used in making alcoholic drinks and bread. Essentially, they both process glucose without oxygen but produce different by-products.