12: Processing of Dairy Products

Question 1

Describe milk standardization and its purpose.

Answer 1

• Standardization of milk involves separating the raw milk to obtain skim milk and milk fat, then homogenize milk fat and skim milk at specific fractions.
• The purpose of standardization is to achieve the targeted milk fat content and reduce variation of quality among different batches of milk.

Question 2

What are the contents of milk?

Answer 2

• Protein (casein and whey)
• Milk fat
• Lactose
• Calcium
• Water and fat soluble vitamins

Question 3

Describe the processing steps of milk production.

Answer 3

1 Receiving: The processing plant checks the fresh milk for its quality.
2 Standardization
3 Pasteurization
4 Homogenization
5 Aseptic Filling

Question 4

Why do we homogenize milk?

Answer 4

To reduce the size of fat globules, improve emulsion stability and improve texture

Question 5

Describe the processing steps of yogurt production

Answer 5

1.Receiving raw ingredients
2. Standardization
3. Culture handling: Prepare L bulgaricus and S thermophilus culture
4. Yogurt mix blending: Add and blend other ingredients (e.g., sweeteners, stabilizers)
5. Homogenization and pasteurization
6. Inoculation, fermentation and cooling
7. Addition of fruit, flavor and color.
8. Filling and packaging

Question 6

Describe the processing steps of ice-cream production.

Answer 6

1. Blending
2. Homogenization
3. Pasteurization
4. Aging
5. Freezing
6. Hardening

Question 7

What happens during the aging process of ice-cream production.

Answer 7

• Ice-cream mix is stored at low temperatures
• Allow recrystallization of fat crystals
• Allow hydration of hydrocolloids
• Adsorption of protein at fat-water interface.

Question 8

How can ice-cream be graded?

Answer 8

• Economy: Milk fat content and overrun fulfils minimum requirement of regulations
• Standard: In between economy and premium
• Premium: High milk fat, low overrun, and use natural flavorings
• Super-premium: Higher milk fat, lower overrun than premium.

Question 9

What are the components of ice-cream?

Answer 9

• Milk fat: Contribute to creaminess, body texture and melting resistance. Calorie-dense, viscous, and prone to oxidation.
• Milk solid non-fat: Contribute to texture, body, and source of protein, minerals and vitamins. May cause sandiness and cooked flavor
• Sweetener: Impart sweet flavor, but impede freezing,

Question 10

Compare between emulsifier and stabilizer.

Answer 10

Emulsifier is a surfactant to facilitate the mixing of fat and water and provide a smooth texture

Stabilizer functions to prevent wheying-off

Question 11

What is the purpose of hardening an ice-cream?

Answer 11

• To allow remaining water from the ice-cream mix to freeze and form small ice-crystals.