What You Need to Know
Barley malt supplies alpha‑ and beta‑amylases that hydrolyze starch into maltose and dextrins, which are then fermented by yeast into ethanol and CO₂, while lactic acid bacteria produce lactic acid, lowering pH and contributing to sour flavor. The reduced atmospheric pressure at 3,000–4,500 m lowers the boiling point of water, diminishing amylase activity and requiring longer bulk fermentation to achieve comparable sugar conversion. Cooler ambient temperatures slow yeast metabolism, extending bulk fermentation to 12–24 h and proofing to 6–10 h while maintaining dough temperature of 20–22 °C in insulated vessels.
The Science
Primary Reaction
Starch hydrolysis by amylases → fermentable sugars → yeast fermentation to ethanol/CO₂ + lactic acid bacteria fermentation to lactic acid