Fermentation

Fermentation

It is a process used to produce alcohol e.g. beer and wine. The microbe used is yeast
Main stages of fermenting yeast
1. 1. Extract sugar
  1. 2. Add yeast
    1. 3. Adjust temperature for yeast growth
      1. 4. Ferment mixture into airtight container to prevent entry of air and microorganisms
        5. Clarify beer (makes yeast settle)
        6. Draw out the alcohol
        7. Pasteurise and bottle the beer
The breakdown of sugar by yeast in the absence of oxygen = anaerobic respiration
1. sugar -> ethanol + carbon dioxide + energy
  1. C6H12O6 -> 2C2H5OH +2CO2
    1. If oxygen is present = aerobic respiration
      1. sugar + oxygen -> water + carbon dioxide
Yeast and Alcohol
1. Different strains of yeast give alcohol different flavours and strengths
2. Usually the high concentration of alcohol produced by the yeast cells kills them making the drink safe for humans
3. Yeast that can tolerate high levels of alcohol are used to produce drinks with a higher alcohol content e.g. vodka
Effect of temperature on yeast
1. For every 10 degree celcius rise, the yeast doubles
  1. Until it reaches the optimum and then the yeast decreases
    1. This is because the enzymes are denaturing

Resource summary

	Created by alice.finlay about 10 years ago