How is ethanol made by fermentation?

Ethanol is produced through fermentation by the anaerobic action of yeast enzymes on simple sugars, such as dextrose, maltose, or glucose.12

The Process

• Preparation: Raw materials—typically grain mashes, fruit juices, or molasses—are adjusted for acidity (pH) to create an optimal environment for yeast.1
• Conversion: Yeast cells are added to the mixture. Through a complex chemical process, the yeast breaks down the sugars into ethyl alcohol and carbon dioxide.132
• Conditions: Commercial fermentation occurs in large vats where temperature is carefully controlled, typically between 24 and 29 °C (75 to 85 °F), to ensure efficient sugar breakdown over 48 to 96 hours.1
• Concentration: The resulting mixture is a dilute aqueous solution. To obtain higher concentrations, the product must undergo fractional distillation.4

This biological pathway is a fundamental method for creating alcoholic beverages and industrial biofuel.42