The Role of Pasteurized Homogenized Milk in Dairy Product Processing

 

1. Introduction

Milk is one of the most versatile raw materials in the food industry. Before being used in various dairy products, milk typically undergoes two critical treatments:

• Pasteurization: A thermal process to kill pathogenic microorganisms and extend shelf life.
• Homogenization: A mechanical process to break down fat globules and prevent cream separation.

Together, these processes produce pasteurized homogenized milk, which serves as the base for a wide range of dairy products. This article explores the role of pasteurized homogenized milk in dairy processing and the products that can be derived from it.

2. What is Pasteurized Homogenized Milk?

Pasteurization

• Typically involves heating milk to 72°C for 15 seconds (HTST) or 63°C for 30 minutes (LTLT).
• Purpose: Destroy pathogenic bacteria such as Listeria, Salmonella, and E. coli.
• Ensures safe consumption and enhances shelf life.

Homogenization

• Milk is forced through small orifices under high pressure (1500–2500 psi).
• Reduces the size of fat globules (<2 µm), making them uniformly distributed.
• Prevents cream separation, improves mouthfeel, and enhances product stability.

3. Applications of Pasteurized Homogenized Milk in Dairy Processing

Pasteurized homogenized milk serves as the foundation for various dairy products, both fermented and non-fermented. Below are the major categories:

A. Fluid Milk Products

1. Whole Milk (3.25% fat)
• Directly packaged after pasteurization and homogenization.
• Consumed as a staple beverage.
2. Low-Fat and Skim Milk
• Standardized to 1%, 2%, or <0.5% fat after homogenization.
• Used by health-conscious consumers.
3. Flavored Milk
• Cocoa, vanilla, strawberry added to base milk.
• Requires additional stabilization and heat treatment for shelf life.

B. Fermented Milk Products

Pasteurized homogenized milk is an ideal medium for cultured dairy products, as homogenization improves texture and uniformity.

1. Yogurt
• Milk is fortified with solids (e.g., milk powder), pasteurized again, and inoculated with Streptococcus thermophilus and Lactobacillus bulgaricus.
• Homogenization ensures a smooth, thick texture.
2. Lassi and Buttermilk
• Traditional Indian drinks prepared from fermented milk.
• Sweet or salted flavors can be added.
3. Kefir
• A probiotic drink produced using a symbiotic culture of bacteria and yeasts (SCOBY).
• Homogenization prevents fat separation and gives a smoother texture.
4. Acidophilus Milk
• Milk fermented with Lactobacillus acidophilus for digestive health.
• Requires precise temperature and culture control.

C. Cheese Production

While homogenized milk is not ideal for rennet coagulated cheeses (like cheddar), it can be used in fresh and soft cheeses:

1. Cottage Cheese
• Uses pasteurized milk; homogenization helps in curd size control.
• Produces soft curds with uniform texture.
2. Cream Cheese
• Homogenized milk blended with cream yields a rich, smooth product.
• Lactic acid fermentation is used for acidification.
3. Ricotta and Paneer
• Acid-set cheeses made by adding acid (e.g., lemon juice, vinegar) to heated milk.
• Pasteurization is critical for safety; homogenization enhances moisture retention.

D. Ice Cream and Frozen Desserts

• Milk fat and non-fat milk solids from homogenized milk provide body and creaminess.
• Homogenization is critical to avoid fat clumping and improve overrun (air incorporation).
• Pasteurization ensures microbial safety before freezing.

E. Milk-Based Beverages and Nutritional Drinks

1. Protein Shakes and Fortified Milk
• Homogenized milk is used as a base to which proteins, vitamins, and minerals are added.
• Ready-to-drink (RTD) nutritional beverages often rely on stable homogenized milk emulsions.
2. Chocolate Milk
• Requires fine dispersion of cocoa solids and stabilization.
• Homogenized milk prevents fat flotation and cocoa sedimentation.

F. UHT and Shelf-Stable Products

• Ultra-High Temperature (UHT) processing (135–140°C for 2–5 seconds) is applied to pasteurized, homogenized milk for long shelf-life.
• Used for:
• Long-life milk
• Single-serve flavored drinks
• Institutional supply milk

4. Functional Role of Homogenized Milk in Processing

Function	Effect in Dairy Products
Fat distribution	Prevents cream line, ensures even flavor/mouthfeel
Improved texture	Enhances body and creaminess (yogurt, cream cheese)
Increased stability	Prevents phase separation (in flavored milk, drinks)
Enhanced emulsification	Improves ice cream and beverage formulation
Better fermentation substrate	Increases surface area for bacterial growth

5. Considerations for Using Homogenized Milk

Aspect	Comments
Cheese Making	Not ideal for hard cheeses – affects rennet coagulation
Shelf Life	Pasteurization provides 7–14 days under refrigeration
Nutrient Stability	Minimal loss of vitamins; proteins remain intact
Flavor	Slight cooked flavor may occur with high-temp pasteurization

6. Conclusion

Pasteurized homogenized milk is a versatile and essential ingredient in the dairy industry. It enables consistent quality, improved safety, and enhanced functionality in a wide range of dairy products—from fluid milk to cultured products, cheeses, and frozen desserts.

Understanding the functional roles of homogenization and pasteurization helps dairy processors tailor their operations to meet product-specific requirements and market demands, while ensuring product safety, consumer satisfaction, and regulatory compliance.