From Cow to Dairy Products: Milk Processing, Separation, and Product Yields

 

1. Milk Production by One Cow

The average dairy cow can produce 25 to 35 liters of milk per day, depending on the breed, health, nutrition, and milking frequency. For our calculation, let's consider 30 liters of milk per day per cow.

2. Separation of Whole Milk into Cream and Skim Milk

Once collected, the whole milk is typically separated into cream and skim milk using a centrifugal separator. This process utilizes centrifugal force to separate the lighter fat (cream) from the denser skim milk.

Separation Yield:

• Cream: ~3.5% to 4% of whole milk (by volume), depending on the fat content of the milk.
• Skim Milk: ~96% to 96.5% of whole milk.

Example:
From 30 liters of whole milk:

• Cream: ~1.05 liters (3.5%)
• Skim Milk: ~28.95 liters (96.5%)

 

3. Use of Skim Milk in Cottage Cheese Production

Skim milk is pasteurized and used in making cottage cheese, a fresh, unripened cheese.

Cottage Cheese Yield:

• Cottage Cheese Curds: ~10% to 12% of the skim milk used.
• Whey (Liquid By-product): ~88% to 90%.

Example (from 28.95 L skim milk):

• Cottage Cheese: ~2.9 to 3.5 kg
• Whey: ~25.5 to 26 L

Whey contains water, lactose, soluble proteins, and minerals and can be used in animal feed, protein powders, or fermented into beverages.

4. Use of Cream in Butter Production

The separated cream is pasteurized and then churned to produce butter.

Butter Yield from Cream:

• Butter: ~35% to 40% of cream (by volume/weight)
• Buttermilk: ~60% to 65%

Example (from 1.05 L cream):

• Butter: ~0.37 to 0.42 kg
• Buttermilk: ~0.63 to 0.68 L

5. Uses of Buttermilk

Buttermilk is the liquid left after churning cream into butter. It is:

• Used in baking (pancakes, biscuits, bread)
• Used as a fermentation base for cultured products
• Used in animal feed or further processed into buttermilk powder
• Sometimes blended into low-fat dairy beverages

6. Use of Pasteurized Homogenized Milk (Homo Milk)

Homogenized milk is whole milk that has been processed to break down and evenly distribute fat molecules, preventing cream separation.

Homo Milk Applications:

Homogenized and pasteurized milk is directly used or further processed into:

• Fluid drinking milk (3.25% fat)
• Flavored milk (chocolate, strawberry)
• Yogurt (whole milk yogurt)
• Lassi and kefir (fermented beverages)
• Cheese (e.g., mozzarella, cheddar)
• Evaporated and condensed milk
• Ice cream and frozen desserts

Summary of Dairy Flow and Conversion Rates

Stage	Product	Yield (%)
Whole Milk (30 L)	Cream	~3.5% (~1.05 L)
	Skim Milk	~96.5% (~28.95 L)
Skim Milk → Cottage Cheese	Cottage Cheese Curds	~10% (~2.9-3.5 kg)
	Whey	~90% (~25.5-26 L)
Cream → Butter	Butter	~35-40% (~0.4 kg)
	Buttermilk	~60-65% (~0.65 L)

Conclusion

From a single cow's milk production, a wide variety of dairy products are created through mechanical separation and thermal processing. Understanding the yields and uses of each milk component helps optimize production in a dairy plant and supports product innovation across the industry. Each part of milk—whether fat, protein, or lactose—is utilized efficiently in creating value-added products.

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