Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Yogurt

11,874 views

Published on

Published in: Health & Medicine, Business
  • Be the first to comment

Yogurt

  1. 1. Yogurt A form of fermented milk produced in most countries where fresh milk is drunk.
  2. 2. Yogurt <ul><li>Yogurt is produced by the controlled fermentation of milk by two species of bacteria Lactobacillus bulgaricus and Lactotococcus thermophilus (also known as Streptococcus thermophilus) </li></ul>
  3. 3. Yogurt <ul><li>The sugar in milk (called lactose) is fermented to acid (lactic acid) and it is this that causes the characteristic curd to form. </li></ul>
  4. 4. Yogurt <ul><li>Streptococcus thermophilus brings the pH of the milk down to 5.5 </li></ul><ul><li>Lactobacillus bulgaricus converts lactose to lactic acid </li></ul>
  5. 5. Yogurt <ul><li>The two bacteria have a mutually stimulating effect on one another. </li></ul><ul><li>Proteolytic enzymes from L. bulgaricus break down milk proteins into peptides. </li></ul>
  6. 6. Yogurt <ul><li>These peptides stimulate the growth of L. thermophilus which in turn produces formic acid and carbon dioxide </li></ul><ul><li>These are growth stimulants for the L. bulgaricus. </li></ul>
  7. 7. Yogurt <ul><li>At the end of the incubation pH may fall to as low as 4.2 – 4.4 </li></ul><ul><li>The lactic acid coagulates the remaining milk proteins, causing the yoghurt to thicken. </li></ul>
  8. 8. Yogurt <ul><li>Acetaldehyde, a metabolic by product of both species, gives raw yoghurt its characteristic flavour. </li></ul>
  9. 9. Yogurt <ul><li>Incubation takes 12 hours at 32 o C to reach the set point of natural yoghurt </li></ul><ul><li>Sugar, colour and fruit pulp is often added to increase popularity of product. </li></ul>
  10. 10. Yogurt <ul><li>Yogurt is a nutritious dessert and its manufacture is an ideal way of using up Europe’s excess milk production </li></ul>
  11. 11. Yogurt <ul><li>Some yoghurts may receive additional heat treatment to kill off any living bacteria before or after packaging for the consumer </li></ul>
  12. 12. proteins peptides
  13. 13. proteins peptides Lactobacillus thermophilus
  14. 14. proteins peptides Lactobacillus thermophilus Lactobacillus bulgaricus Proteolytic enzymes
  15. 15. proteins peptides Lactobacillus thermophilus Lactobacillus bulgaricus Proteolytic enzymes formic acid + CO 2
  16. 16. proteins peptides Lactobacillus thermophilus Lactobacillus bulgaricus Proteolytic enzymes formic acid + CO 2 lactic acid
  17. 17. proteins peptides Lactobacillus thermophilus Lactobacillus bulgaricus Proteolytic enzymes formic acid + CO 2 lactic acid acetaldehyde
  18. 18. Raw milk
  19. 19. Raw milk Pasteurised Milk pasteurisation
  20. 20. Raw milk Pasteurised Milk pasteurisation Raw Yogurt homogenisation cooling incubation add starter
  21. 21. Raw milk Pasteurised Milk pasteurisation Raw Yogurt homogenisation cooling incubation add starter Processed Yogurt (heat treatment) packaging (heat treatment) add fruit/flavour

×