Yes, sour milk does separate.
What Happens When Milk Sours?
When milk goes sour, it's due to the activity of bacteria. These bacteria break down lactose (the sugar in milk) into lactic acid. This process lowers the pH of the milk, making it more acidic. As the milk becomes more acidic, the proteins in the milk begin to denature, which leads to the separation you observe.
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The spoilage is caused by bad bacteria and the milk will actually separate. It will taste and smell bad and will most likely upset your stomach if you try to drink it.
How to Recognize Milk Separation
- Visible Layers: The milk will typically divide into distinct layers. The top layer will be a watery, clear or yellowish liquid (whey), while the bottom layer will contain thicker curds or solids.
- Changes in Texture: The overall texture of the milk becomes thicker and more curdled rather than smooth.
- Unpleasant Odor: Sour milk develops a distinctive, sharp, and sour smell. This is a clear indication of spoilage.
- Taste: Sour milk will have a bitter and acidic flavor, quite unlike fresh milk. It is not recommended to consume sour milk.
Factors Affecting Separation
- Pasteurization: Pasteurized milk may sour slightly more slowly than raw milk. However, both will eventually separate as bacterial activity increases.
- Temperature: Higher temperatures accelerate bacterial growth, causing milk to sour and separate faster.
- Time: Given enough time at room temperature, even pasteurized milk will spoil and separate.
Practical Advice
- If you notice your milk starting to separate, it's best not to drink it.
- Check the expiration dates on your milk cartons and store it properly in the refrigerator to prevent premature spoilage.
