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Biotechnological Industries

Biotechnological Industries. Unit 2. Dairy Industries. Chapter 5. Milk. Normal milk contains sugar, fat, protein, vitamins & minerals Sugar – provides energy Fats – energy & insulation Proteins – growth & repair Vitamins – protect from deficiency diseases

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Biotechnological Industries

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  1. Biotechnological Industries Unit 2

  2. Dairy Industries Chapter 5

  3. Milk • Normal milk contains sugar, fat, protein, vitamins & minerals • Sugar – provides energy • Fats – energy & insulation • Proteins – growth & repair • Vitamins – protect from deficiency diseases • Minerals – helps bones, blood, teeth, skin

  4. Milk treatment • Can be treated/processed: • a) removal of fat (skimmed/semi-skimmed) • b) heat treatment • - pasteurisation (72oC for 15 secs, then cooled) • - UHT (138oC for 2-5 secs) • - both help prevent bacterial growth • - Resauzarin dye test for presence of bacteria (purple – white) • c) evaporation (condensed) – milk heated to reduce water content

  5. Yoghurt • Produced from milk • Yoghurt-forming bacteria added to heat treated milk • Bacteria change sugar into lactic acid • - this ‘clots’ & ‘thickens’ the milk • Yoghurt is therefore tangy, acidic & slightly sour • Most bacteria can’t grow in these acid conditions • – natural preservative • ‘Natural’ & ‘Bio’ yoghurts contain live bacteria

  6. Yoghurt production

  7. Cheese • A solid food made from a liquid (milk) • Milk needs to curdle first • - cheese making bacteria are added • - they change sugar into lactic acid • Rennet is added to help the milk to curdle • - milk changed into curds (solid) & whey (liquid) • - acid clots the milk proteins into curds • Curds are chopped and mixed with salt • - cheese left to mature & develop flavour • Whey can be re-used as part of cattle feed

  8. Environmental Impact • In the past whey was disposed of as waste • Often poured into rivers/lakes • But, whey is rich in protein • So bacteria in rivers fed on the whey • More bacteria led to other species dying • - due to a lack of oxygen • Upgrading • Whey is now used as a feed for yeast • Also used for pig food • Whey powder used in many human foods

  9. Aseptic Conditions • When working with micro-organisms, conditions must be sterile or aseptic • - prevents experiment being contaminated • - prevents micro-organisms escaping from experiment • The following conditions should be used: • - no eating or drinking • - using protective clothing • - washing hands • - suitable work surfaces (glass/plastic) • - sterilised equipment (e.g. autoclave) • - a sterile inoculating loop to transfer microbes

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