Health Milk

Milk

Milk (drinks)

Milk is rich in nutrients such as protein, fat, vitamins, and minerals. Milk protein contains amino acids necessary for the human body; milk fat is mostly short-chain and medium-chain fatty acids, which is easily absorbed by the body; potassium, phosphorus, calcium, etc. The ratio of minerals is reasonable, which is easy for human body to absorb

Sterilized fresh milk: Sterilized fresh milk is a liquid milk product made by pasteurization (63 ℃, 30min. Or 75 ~ 90 ℃, 15 ~ 16sec.), Which needs to be kept in cold storage. [2]

Sterilized milk: UHT milk is made by high-temperature instant sterilization (120 ~ 140 ℃, 1 ~ 2sec.), And can be stored at normal temperature for 30 ~ 40 days. Traditional sterilized milk is a liquid milk product made by long-term high-temperature sterilization, which can be stored at room temperature for more than 6 months. [2]

The content of nutrients such as protein, lactose and minerals in sterilized fresh milk and sterilized milk is basically the same as raw milk. Only B vitamins have a small loss, but the preservation rate of sterilized milk is usually above 90%, and sterilized milk is also More than 60%, the loss of vitamin C is greater, but because it is not an important nutrient in milk, it has little effect on the nutritional value of dairy products. Commercially sterilized milk often strengthens vitamin A and vitamin D, making it a two One of the cheapest and most convenient food sources of nutrients. [2]

"Raw milk" is also commonly called raw milk (Raw Milk), and is a common name for raw milk that has not been sterilized and homogenized. A small amount of "raw milk" is currently sold in bulk on the market, and consumers generally boil it for drinking after purchase. The commercially available pre-packaged pure milk in boxed or bagged form is to "fresh milk" after cooling, raw milk inspection, impurity removal, standardization, homogenization and sterilization (pasteurization or ultrahigh temperature sterilization) The products made by other processes are in accordance with relevant national standards. Due to the lack of homogenization process, the "fresh milk" has large milk fat globules, which will aggregate and float after boiling, thus bringing a "sticky" and "dense flavor" sensory impression. However, studies have shown that there is no significant difference in nutrition and human health between "raw milk" and pasteurized milk.

The main cause of microbial contamination of "fresh milk" is E. coli, Staphylococcus aureus, Pseudomonas, fungi, etc. from the environment, and Brucella, Mycobacterium tuberculosis, etc. originating from animals Germs, etc. Therefore, if the "raw milk" is not sufficiently sterilized, it is easy to cause the spread of zoonotic diseases. "Raw fresh milk" has not been subjected to any disinfection treatment, and the information about whether the milking cows are healthy, whether they are quarantine, or whether they are contaminated during transportation is difficult to fully trace, and there are certain hidden food safety risks. Especially children, the elderly, pregnant women and people with low immunity have a greater risk of infection by pathogenic bacteria after eating "raw milk". There are reports of food poisoning caused by eating "raw milk" at home and abroad. Therefore, consumers are advised not to drink "raw milk" directly. 

Nutritional characteristics

Milk and its products are one of the important sources of protein, calcium, phosphorus, vitamin A, vitamin D and vitamin B2 in the diet. [2]

. The specific gravity of cow milk is 1.032 on average, and the specific gravity is related to the solid content in milk. In addition to the relatively large changes in fat content, the other components of milk are basically stable, so the specific gravity can be used as a simple indicator for evaluating the quality of fresh milk. [2]

protein

The protein content in milk is 2.8% ~ 3.3%, mainly composed of 79.6% casein and 11.5%

Whey (white) protein is composed of 3.3% lactoglobulin, and a small amount of other proteins, such as immunoglobulins and enzymes. Where cow's milk protein precipitated at pH 4.6 at 20 ° C is called casein. Casein is a heat-resistant protein, but it can be precipitated under acidic conditions. Yogurt and cheese are made based on this principle. In milk, casein combines with calcium and phosphorus to form casein colloidal particles and exists in the milk in the state of colloidal suspension. Whey protein is unstable to heat and coagulates and precipitates when heated. The digestion and absorption rate of milk protein is 87% ~ 89%, and its biological value is 85, which is high-quality protein. [2]

fat

Dairy fat is about 2.8% to 4.0%. It is dispersed in the emulsion in the form of particulate fat globules, which is in a very good emulsified state, easy to digest and absorb, and the absorption rate is as high as 97%. The lipids in cow's milk are mainly triglycerides, a small amount of phospholipids and cholesterol, the fatty acid composition in milk fat is complex, oleic acid accounts for 30%, linoleic acid and linolenic acid account for 5.3% and 2.1%, respectively, and short-chain fatty acids (such as Butyric acid, caprylic acid, caprylic acid) content is relatively high, about 9%, which is the reason why milk fat has a good flavor and is easy to diges