Milk Flashcards
How much milk is needed for 1kg of cheese?
8.5kg
How much milk is required to make 1kg of whole milk powder?
7.81kg
How much milk is required to make 1kg skimmed milk powder?
10.72kg
How much milk is needed to make 1kg of condensed milk?
2kg
How much milk is needed to make 1kg of yoghurt/buttermilk?
1.1kg
What are the milk quality tests?
Organoleptic- visual and odour
Protein content- Kjeldahl process
Milk fat content- Gerber method
NIR (near infrared) can be used to measure fat, protein and lactose
How much milk solids are in condensed milk?
50-60%
Sweetened condensed milk contains how much milk solids?
70%
How is milk powder made?
Drum drying or spray drying
Homogenisation of milk
Fat globules obtain a surface rich in casein proteins therefore they can behave as large casein micelles which forms a stable and uniform suspension of fat
Why are small milk fat globules easier to digest than large milk fat globules?
Due to the larger surface area to volume ratio of smaller droplets
Name the 4 ways to heat treat milk
Thermization, low pasteurization, high pasteurization and sterilization
Thermization
65°C for a few seconds
Low pasteurization
63°C for 30 mins or 72°C for 15 seconds
High pasteurization
85°C for 20 seconds
Sterilization
110°C for 30 mins, 130°C for 30 seconds or 145°C for 1 second (UHT)
How does heating change milk?
- Colour (more brown)
- Flavour (Maillard reaction)
- Texture (whey protein associating with casein micelles)
- Nutritional value (ketone formation)
Why do reaction rates vary?
Water activity (Aw)
Concentrated milk products
Deteriorate at intermediate Aw values
When does water activity of milk increase?
When heated therefore reactions decrease when temperature increases
Milk definition
An aqueous solution of protein, fat, vitamins and minerals that carries emulsified fat globules and a dispersion of casein micelles
What is milk made from?
- 87.5% water
- 3.9% fat (TAG)
- 3.4% protein
- 5.2% vitamins and minerals
What are the 2 proteins of milk?
- 80% casein
- 20% whey
What is the structure of casein?
- Short lengths of alpha-helix and beta-sheet
- Hydrophilic and hydrophobic regions
