Food Biochemistry and Food Processing

20 Biochemistry of Milk Processing 455

Table 20.1.Diversity of Dairy Products Produced by Different Processes

Process Primary (bold) and Secondary Products

Heat treatment (generally Market milk
with homogenization)
Centrifugal separation Standardized milk
Cream
Butter, butter oil, ghee
Creams of various fat content (pasteurized or UHT-treated); whipping,
coffee, dessert creams
Skim milk
Skim milk powder, casein, cheese, protein concentrates
Concentration (e.g., evaporation In-container or UHT-sterilized concentrated milks, sweetened
or membrane separation) condensed milk
Concentration and drying Whole milk powders, infant formulas
Enzymatic coagulation Cheese
Numerous varieties, processed cheese, cheese sauces and dips
Rennet casein; cheese analogs
Whey
Whey powders; demineralized whey powders; whey protein
concentrates; fractionated whey proteins; whey protein hydrolysates;
lactose and lactose derivatives
Acid coagulation Cheese (fresh)
Acid casein; functional proteins
Whey(as rennet whey)
Fermentation Various fermented milk products, e.g., yogurt, buttermilk, acidophilus
milk, bioyogurt
Freezing, aeration, and whipping Ice cream

Source:Adapted from Fox and McSweeney 1998.

Table 20.2.Thermal Processes Commonly Applied to Liquid Milk Products

Process Conditions Heat Exchanger Reason
Thermization 63°C for 15 s Plate heat exchanger Killing psychrotrophic bacteria
before cold storage of milk
Pasteurization 72–74°C for Plate heat exchanger Killing of vegetative pathogenic
15–30 s bacteria and shelf-life extension
UHT (indirect) 135–140°C Plate heat exchanger Production of safe long-shelf-
for 3–5 s life milk
Scraped-surface heat
exchanger
Tubular heat exchanger
UHT (direct) 135–140°C Steam infusion system Production of safe long-shelf-
for 3–5 s life milk
Steam injection system
Sterilization 118°C for Batch or continuous Production of sterile milk
12 min retort