What You Need to Know
The process relied on spontaneous yeast activity from grape skins and the surrounding environment, with spontaneous fermentation converting sugars to ethanol and CO₂. Crushed skins and aromatic herbs were added to enhance tannin extraction and inhibit spoilage, while occasional sulfur dioxide (30–50 ppm) was used to prevent oxidation and bacterial growth. The technique of sun‑drying grapes before fermentation increased sugar concentration, producing a sweeter, more concentrated wine.
The Science
Primary Reaction
Alcoholic fermentation of sugars by yeast (Saccharomyces spp.) producing ethanol and CO₂