Why does unrefrigerated milk spoil so quicky?
In: Biology
To add what others have said, milk is incredibly nutrient rich. Bacteria thrives in nutrient-rich environments. Keeping milk (or any food) cold slows down the growth of bacteria that will spoil the food. When you leave food out and its temperature rises, it makes it a more hospitable environment for the bacteria to thrive and spoil the food faster.
By spoiling, do you mean curdling (turning into clumps)?
Milk is composed of fat and water. Fat and water does not mix. However, there is a special protein in milk that makes it possible. The protein is Casein. It is an emulsifier. When exposed to heat, proteins break down and no longer keep the fat and water mixed.
Milk is full of nutrients and sugars and fats with typically a neutral or very mildly acidic PH, a perfect haven for bacteria.
Most of our other common drinks are either highly acidic(juice, soda, coffee), so dense in sugar or salt that it ironically makes the liquid hostile for freshwater bacteria(soda, energy drinks), or were boiled prior to serving(coffee, tea), which makes them slower to spoil. And alcoholic beverages are obviously outright poisonous to microbes as long as the alcohol content is high enough.
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