Question

what do you mean by fermentation

Answer 1

Fermentation is a metabolic process that consumes sugar in the absence of oxygen. The products are organic acids, gases, or alcohol. It occurs in yeast and bacteria, and also in oxygen-starved muscle cells, as in the case of lactic acid fermentation.

Answer 2

Fermentation is a metabolic process that produces chemical changes in organic  substratescthrough the action of enzymes