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History of Biotech

History of Biotech. Ancient bread baking Wine brewing Cheese making Yogurt fermentation Animal and plant breeding. Yogurt. Yogurt. Yogurt is produced by the controlled fermentation of milk by two species of bacteria Lactobacillus bulgaricus and Streptococcus thermophilus. Yogurt.

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History of Biotech

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  1. History of Biotech • Ancient bread baking • Wine brewing • Cheese making • Yogurt fermentation • Animal and plant breeding

  2. Yogurt

  3. Yogurt • Yogurt is produced by the controlled fermentation of milk by two species of bacteria Lactobacillus bulgaricus and Streptococcus thermophilus.

  4. Yogurt • The sugar in milk (called lactose) is fermented to acid (lactic acid) and it is this that causes the characteristic curd to form. • Streptococcus thermophilus brings the pH of the milk down to 5.5 • Lactobacillus bulgaricus converts lactose to lactic acid

  5. Yogurt • The two bacteria have a mutually stimulating effect on one another. • Proteolytic enzymes from L. bulgaricus break down milk proteins into peptides.

  6. Yogurt • These peptides stimulate the growth of S. thermophilus which in turn produces formic acid and carbon dioxide • These are growth stimulants for the L. bulgaricus.

  7. Yogurt • At the end of the incubation pH may fall to as low as 4.2 – 4.4 • The lactic acid coagulates the remaining milk proteins, causing the yogurt to thicken.

  8. Yogurt • Acetaldehyde, a metabolic by product of both species, gives raw yogurt its characteristic flavor.

  9. Yogurt • Incubation takes 12 hours at 45o C to reach the set point of natural yogurt • Sugar, color, and fruit pulp is often added to increase popularity of product.

  10. peptides Milk proteins Proteolytic enzymes Streptococcus thermophilus Lactobacillus bulgaricus formic acid + CO2 lactic acid acetaldehyde

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