Production of fermentable extracts from cereals and fruits

Abstract

Alcoholic beverages are consumed primarily because ethanol forms a significant component. The principal organisms in most alcoholic beverage fermentations, yeasts, are able to produce ethanol primarily through metabolism of the low-molecular-weight sugars that can be transported into the cell cytoplasm. Thus, in production processes utilising cereals or tubers, fermentations must be preceded by a depolymerisation of storage polysaccharides and proteins yielding the sugars and amino acids that can be utilised by the microorganism. In cereals, storage polymers are enclosed by plant cell walls into compartments that limit losses through hydration, enzymic and also microbial attack. As these cell walls are also predominantly formed from polysaccharides, their breakdown yields further sugars: hexoses, which can be metabolised by the dominant yeast Saccharomyces cerevisiae, and pentoses that are not metabolised by S. cerevisiae but are frequently catabolised by lactic acid bacteria.