Brewing - Yeast

• Yeast respires anerobically (fermentation); Glucose → ethanol + carbon dioxide (C_6H_12O_6 → 2C_2H_5OH + 2CO_2)
• Commercial process: - Malting: barley germinates, enzymes are produced to break starch into sugars for yeast to respire - Mashing: malt mixed with hot water (55-65°C); enzymes break down starch producing wort, hops added for the bitter flavour - Fermentation: yeast added to wort, and is eventually killed as pH lowers, ethanol builds up and oxygen decreases - Maturation: beer conditioned for 4-29 days (2-6°C), then it is filtered, pasteurised, bottled/canned
• Commercial process:

  Malting: barley germinates, enzymes are produced to break starch into sugars for yeast to respire

  Mashing: malt mixed with hot water (55-65°C); enzymes break down starch producing wort, hops added for the bitter flavour

  Fermentation: yeast added to wort, and is eventually killed as pH lowers, ethanol builds up and oxygen decreases

  Maturation: beer conditioned for 4-29 days (2-6°C), then it is filtered, pasteurised, bottled/canned