Dairy Products

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Proteins

  • Caesin
  • Lactoglobulin
  • Lactalbulmin
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Lactose Content

  • 4-5% in cows milk
  • 6-8% in human milk
  • Reducing sugar - glucose, galactose
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Pasteurisation

  • Short heat procees - 15 seconds
  • Low temp - 72c
  • Short shelf life - 7-10 days
  • Slight loss of vitamin B1+2
  • No affect on flavour
  • Requires chilling
  • Destroys poisoning not spoilage
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Sterilisation

  • Long heat process -15-25 minutes
  • High temp - 121c
  • Long shelf life - 6 months
  • Significant loss of vitamins
  • Caramel taste
  • Destroys all bacterial cells
  • Does not require chilling
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Why?

  • Pasteurise - destroy bacteria e.g. TB, reduce waste, reduce spoilage, extend shelf life
  • Sterilise - reduce spoilage, destroy all bacterial cells, people prefer cooked taste
  • Homogenise - prevent separation of fat during storage by reducing size of fat globules
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Evaporated + Condensed

  • Evaporated - evaporating water from milk, water content 70%, poor granular texture, higly perishable so needs to be homogenised
  • Condensed - 1st pasteurised, sweetened with sugar syrup (60-65% sucrose)
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Dried + Skimmed

  • Dried - Spray dryer, milk concentred in evaporator, sprayed whilst still hot (80c) into a chamber where spray meets hot air (180c) and dries instantly
  • Skimmed - Cream separator, rotates at high speeds (6500rpm), centrifugal force separates heavier skimmed milk from cream
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Chemical Changes

  • Enzymes in bacteria convert lactose to lactic acid
  • Lowering of pH affects caesin
  • Presence of lactic acid bacteria
  • Bacteria - lactic acid, lactococcus, lactobacillius
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Mould Growth on Cheese

  • Flavour, texture, smell, colour changes
  • Mould growth on surface
  • Ammonia produced
  • Some fatty acids released from fat
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Butter

  • Cream separated from milk
  • Bacteria starter culture added
  • Churning the cream
  • Butter fat and Butter milk separated
  • Butter fat worked to right moisture level
  • Salt may be added
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Ice Cream

  • Ingredients mixed together
  • Homogenised
  • Pasteurised
  • Frozen (-5c)
  • Fast freeze = small ice crystals
  • Air whipped in during freezing
  • Hardened at -40c
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Yoghurt

  • Milk
  • Pasteurised to destroy pathogens
  • Cooling at 40-44c, optimum temp for bacterial growth
  • Addition of starter - Lactobacillius Bulgarius
  • Grow over incubation period, ferment the lactose, increase in acidity will thicken texture, give required flavour from production of diacetyl
  • Cooling - 5-8c ****** growth until consumption
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Sugar Refining

  • Take sugar beet
  • Wash sugar beet
  • Chop the sugar beet
  • Stew the beet in hot water and water kept
  • Mixture is then filtered to remove solids
  • Extract sugar - add CO2 and lime solution to from chalk, chalk traps impurities, chilk filtered out, remaining juice boiled, spun in centrifuge, packed in bags
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