Why milk is turning sour during summer?

Milk is an ideal environment for bacteria to grow, and higher temperatures accelerate bacterial growth. When the temperature rises, the bacteria in milk multiply rapidly, converting the lactose (milk sugar) into lactic acid. This process, known as acidification or souring, causes milk to become tart and eventually curdle.

2. Light:

Exposure to light, particularly sunlight, can also contribute to milk spoilage. The riboflavin (vitamin B2) in milk reacts with light, producing off-flavors and unpleasant odors. Light also promotes the growth of certain bacteria, further accelerating the souring process.

3. Packaging and Storage:

Improper packaging and storage conditions can hasten milk spoilage. Milk should be stored in airtight containers to prevent contamination and kept in the refrigerator at temperatures below 4°C (39°F). Allowing milk to sit out at room temperature or exposing it to open air increases its susceptibility to spoilage.

4. Initial Bacterial Contamination:

Milk can sometimes become sour even before it reaches the consumer due to initial bacterial contamination during milking, processing, or transportation. Poor sanitation practices, such as unsterilized equipment or inadequate cooling during transportation, can introduce bacteria into the milk supply.

5. Type of Milk:

The type of milk also affects its susceptibility to spoilage. Raw milk, which has not undergone pasteurization, contains more bacteria and has a shorter shelf life compared to pasteurized milk. Pasteurization kills most harmful bacteria, but some heat-resistant bacteria may survive and cause spoilage if milk is not handled and stored properly.