What You Need to Know
During fermentation, starches in the acorn mash are hydrolyzed by endogenous amylases and then converted by lactic acid bacteria into lactic acid, lowering the pH to around 4.5–5.0. Trace ethanol is produced by yeasts such as Saccharomyces cerevisiae, contributing to the sour flavor. The process also leaches tannins, reducing astringency and improving digestibility.
The Science
Primary Reaction
Starch → glucose → lactic acid (via lactic acid bacteria) + trace ethanol (via yeasts)