The term for alcoholic fermentation used to refer to the apparent "boiling" or "foaming" in grape must. Fermentation is understood to be the microbial degradation of organic substances without the inclusion of external electron acceptors such as nitrate or oxygen (i.e. anaerobic) for the purpose of energy production. However, the degradation of organic substances can also take place with the inclusion of oxygen (aerobic). For example, acetic acid fermentation consumes oxygen, which is why it is not a fermentation in the scientific sense as described above. The term fermentation, on the other hand, is an umbrella term for aerobic and anaerobic processes. This often leads to confusion because in other languages "fermentation" is used for alcoholic fermentation or there is no separate term for it.
For me, Lexicon from wein.plus is the most comprehensive and best source of information about wine currently available.
Egon Mark
Diplom-Sommelier, Weinakademiker und Weinberater, Volders (Österreich)