Milk contains three different types of water. One of the most abundant free water, free state, not combined with other substances, only play the role of a solvent; combined water, is with proteins, lactose, salts combined with water, no longer dissolve other substances, does not freeze; crystalline water, is in the lactose crystals and lactose crystals together with the presence of water. When milk freezes, the free water freezes first, and the milk freezes from the outside to the inside, which is covered with dry matter (protein, fat, calcium, etc.). As the freezing time is prolonged, the dry matter inside does not freeze, and the milk becomes lighter in color on the outside and darker on the inside. After thawing, the proteins in the milk are deteriorated due to precipitation and coagulation.
For those who have a bad stomach, cold milk enters the stomach, stimulating the gastric mucosa, causing strong vascular contraction, so that gastric acid and digestive enzyme secretion is reduced, gastrointestinal peristalsis is enhanced peristalsis is enhanced, resulting in diarrhea.
So the temperature of the stored milk is 0-3℃. However, it is best to buy and drink now, not easy to save too long