Dairy Products

1
Dairy Products
2
Milk

• raw material microbial load
• heat treatment
• microbial load
• time/temperature
• contamination
• pasteurization inactivates lipase
• heat resistant proteases and lipases of spoilage
  bacteria

3
Heat treatment

• HTST
• 72C / 15 s
• 3-14 d
• HTP (ESL)
• 85-135C
• 107C / gt2 s
• at least 30 d shelf life, 30-90 d
• refrigerated
• aseptic packaging
• UHT
• gt135C
• 6 mo

4
Milk and cream

• Microbial spoilage
• Off-flavors
• hydrolytic rancidity
• oxidation
• Use by date

5
Yoghurt

• acidity development
• yeast and mold growth
• syneresis

6
Butter

• oxidation
• yeast and mold growth
• texture degradation
• graininess
• discoloration

7
Milk powder

• Autoxidation
• Browning
• Texture degradation
• caking
• Off-flavors
• Best before

8
UHT milk

• texture degradation
• proteolysis
• enzymes from psychrotrophs and milk (plasmin)
• age gelation (increase in viscosity)
• off-flavors
• bitterness, rancidity (enzymes from
  psychrotrophs)
• cooked flavor after processing
• stale flavor

9
Cheese

• off-flavors
• hydrolytic rancidity
• contaminant microflora
• oxidation
• texture
• proteolysis
• depends primarily to processing conditions

10
Ice cream

• texture
• temperature fluctuations
• ice recrystallization
• graininess
• lactose crystallization
• off-flavor
• oxidation
• microbial spoilage