Large molecules become smaller
Microbial enzymes partly hydrolyse polysaccharides and proteins into oligosaccharides, peptides and amino acids. Smaller molecules are generally easier for digestive enzymes to reach.
This is also why fermented bases taste softer: part of the astringency comes from polyphenol-protein complexes, and fermentation changes that binding state.
Release and conversion
Many active compounds in plant material exist in bound form. Enzymatic hydrolysis during fermentation can convert them into more accessible forms, while microbial metabolism produces new organic acids, esters and vitamins.
The direction and extent depend on strain, substrate and process — fermentation is not automatically more nutritious.
Anti-nutritional factors
Some raw materials contain phytates or tannins that reduce mineral absorption. Enzymatic activity during fermentation can lower their levels.
Frequently asked
- Can fermented juice replace eating fruit?
- No. Fermentation consumes some sugar, changes composition, and fibre may be removed during filtration. It is not equivalent to whole fruit.
- Is a longer fermentation always better?
- No. Past the target endpoint, acidity keeps rising, sugar keeps falling, flavour sharpens, and the risk of spoilage organisms increases.