What's the harm of drinking milk overnight?

Sterilized milk refrigerated overnight only needs to be heated and boiled. Don't cook it repeatedly. Milk stored at room temperature usually goes bad overnight. I suggest you read the following article to have a good understanding of milk. First of all, we should see that the various names of liquid dairy products in the market can test consumers' commodity knowledge. Pure milk, fresh milk, pure fresh milk, yogurt, active milk and fruit milk are all articles around the word "milk". It's actually quite easy to classify them-there are "protein content" on the label and the list of product ingredients that must be marked, which is nothing more than a choice between pure milk and milk-containing drinks. Pure milk is also called fresh milk and pure milk. As can be seen from the ingredient list of the product, there is only one ingredient, namely fresh milk. From its own nutritional value and the degree of recognition by experts, pure milk is an indispensable "mainstream product". There are two main indexes to evaluate the quality of pure milk: total dry matter (also called whole milk solids) and protein. The contents of these two indicators are generally stated on the packaging bag of the product. The higher their content, the higher the nutritional value of milk. There are two ways to disinfect milk. A senior engineer surnamed Zhang in a dairy factory said that liquid milk can be divided into three types according to the production process: sterilized milk, sour milk and pasteurized milk. As far as disinfection methods are concerned, there are two disinfection methods: pasteurized milk and ultra-high temperature sterilized milk. As far as packaging forms are concerned, it can be roughly divided into four types: plastic bags, tetra pak, cartons and plastic bottles. Tetra Pak packaging bottles are divided into pillow type (bagged) and brick type (boxed), both of which are made of 5-7 layers of paper and aluminum foil. According to experts, the shelf life and drinking method of milk have a great relationship with packaging, and different packaging and disinfection methods determine the shelf life of milk. Pasteurized milk: Also called pasteurized milk. Sterilizing at about 80℃ for a few seconds belongs to "short-acting milk" and needs to be preserved at low temperature. The shelf life is usually 1-7 days. When the storage temperature exceeds 4℃, the bacteria in milk will multiply, so it cannot be stored at room temperature for a long time. Pasteurized milk includes whole milk and partially skimmed milk, which is suitable for families with quick disinfection and high purchase frequency. Bagged milk is cheap, suitable for distribution to thousands of households, and has become breakfast food for many families. House-shaped fresh milk, which looks like a house, is packaged with paper materials that are protected from light and conform to the concept of environmental protection, and adopts the internationally accepted "cold chain control method", that is, the whole process from milk extrusion to production, storage, transportation and sales is carried out at low temperature, and the longest storage period can reach 7 days. One of its characteristics is "freshness": from milk extrusion to product filling in 8 hours; Second, the production technology is advanced and scientific, and the nutritional components are well preserved, and all nutritional indexes are higher than those of ordinary bagged milk. House-shaped milk with rich flavor and mellow taste is a fine product in fresh milk, and its price has been greatly adjusted, and it has begun to approach ordinary people. However, because the price is still at a disadvantage, house-shaped milk can not replace the packaged sterilized milk with good quality and low price for a long time. Ultra-high temperature (pillow bag/brick box) sterilized milk: also called high temperature milk. Using instantaneous ultra-high temperature sterilization method, the sterilization of packaging materials, packaging box molding and packaging are completed in one production line, that is, from packaging molding to product filling, all in a sealed sterile area. Tetra Pak crisper contains 5-7 layers of protective film, which can protect vitamins in milk from sunlight. The ultra-high temperature instant sterilized fresh milk in Tetra Pak's fresh-keeping packaging is "long-lasting milk", which can make consumers reduce the purchase frequency. The product itself does not need to be refrigerated, and the shelf life is generally 8 months at room temperature, but the premise is that once the package is opened in the unopened state, it should be refrigerated in the refrigerator and drunk within 3-4 days as far as possible. Tetra Pak Pillow packaging is economical and practical, and it is also suitable for carrying out. "Sterilization" and "sterilization" are difficult to distinguish. Pasteurization and ultra-high temperature sterilization are two different deep processing methods, and it is difficult to say which is better or worse. The biggest difference between them lies in the different treatment methods of bacteria in raw milk, so the selection and processing of raw milk and the sales, transportation and drinking methods of finished products are different. After pasteurization, protein and most vitamins in raw milk are basically intact, and non-pathogenic bacteria are not completely killed, which means that some lactic acid bacteria, yeasts and molds will remain, so the shelf life will not exceed 2 days; Ultra-high temperature sterilized milk is instantly sterilized at 135- 140℃ within 3-4 seconds, killing all microorganisms in raw milk and preserving the nutrients in milk to the maximum extent, which is called sterilization. Filling process, ultra-high temperature sterilized milk adopts aseptic filling method. In sales and transportation, pasteurized milk needs cold storage conditions, and the shelf life is mostly 48 hours; Ultra-high temperature sterilized milk does not need to be refrigerated, and its shelf life is as long as 8 months at room temperature. Some people think that pasteurized milk can ensure the pure flavor and nutritional value of fresh milk and taste fresher because of the "cold chain control method". In particular, the house-shaped fresh milk adopts advanced packaging materials, which can effectively prevent ultraviolet rays from damaging the nutrition of vitamin A and vitamin B in milk and protect the nutrition, freshness and taste of milk. All products marked with the words "sterilized milk" can be drunk within the shelf life; People who are used to hot drinks should not boil milk until it gets warm. Because if the boiling time is too long, it will not only destroy vitamins, but also cause protein coagulation and calcium precipitation, reducing the nutritional value of milk. Sterilized milk refrigerated overnight only needs to be heated and boiled, not boiled repeatedly. Tetra Pak packaging can resist the invasion of germs, oxygen, ultraviolet rays and moisture to fresh milk, so it can be drunk directly. Be careful not to heat tetra pak products in the microwave oven, because the packaging contains metal components, and sealed packaging items may cause explosion if heated in the microwave oven. Liu Dongsheng, a researcher at the Institute of Health Care, Chinese Academy of Preventive Medicine, said that it is not advisable to drink milk on an empty stomach for breakfast, because the short stay time of milk in the stomach on an empty stomach will affect the digestion and absorption of milk. A few biscuits or bread containing amino acids can not only balance the diet, but also help the absorption of milk. Some experts also remind consumers to pay attention to the way of drinking. Drinking a small amount of milk every day is better than drinking a large amount at a time, and the absorption rate of calcium in human body is higher. Some people with weak gastrointestinal function should sip milk as much as possible, so that milk and saliva can be fully mixed. If swallowed, milk will directly enter the stomach to react with acidic gastric juice, and protein and fat in milk will form lumps, which will not be easily digested by the human body, resulting in diarrhea and discomfort. Moreover, because lactic acid fermentation will produce gas, it will aggravate flatulence, which is not conducive to wound healing. Patients after gastrointestinal surgery should not drink milk. Consumers should also know that milk and many substances cannot be drunk at the same time. For example, tannic acid in tea will hinder the absorption of calcium ions in milk; Taking medicine with milk will also hinder the disease from exerting its medicinal properties. Experts also stressed that although milk is good, if it is drunk like boiled water, it will be "excessive". Water is very important to human body. In order to keep the balance of water in the body, it must be supplemented from the diet. Although milk contains a lot of water, it is a hypertonic drink. If you drink too much, it will easily lead to dehydration, especially when you sweat and lose too much water. Therefore, milk can't replace boiled water. Milk that can't be bought should be stored in freezer instead of freezer, because freezing will precipitate, solidify and deteriorate protein in milk. However, pasteurized milk has a "cold chain", and even if it is left at room temperature for 4 hours, the milk will begin to deteriorate. Therefore, don't buy sterilized milk in stalls without refrigeration equipment. For consumers who can buy bulk "direct selling milk" at home, experts remind that from the perspective of health and safety, they cannot buy bulk "direct selling milk". Experts pointed out that there are many problems in this kind of bulk milk that has not been sterilized by high temperature processing. Even without adulteration, its sanitary conditions cannot be guaranteed. "Direct-selling milk" has not been scientifically sterilized, and it cannot be effectively sterilized by boiling after consumers buy it back. According to statistics, the bacterial content in raw milk is 2.5 million cells /ml after washing milking utensils and milk containers with clean water, and it is only 23,000 cells /ml if the milk is sterilized with steam and then filled. At present, there are some misunderstandings among consumers that the thicker the milk, the better, and the viscous milk with high nutritional content is good milk. The milk just squeezed out is thicker because the fat globules in the milk are bigger, so it looks thicker. In the process of milk processing, there is a step called "homogenization", that is, the fat globules in milk are further crushed, so that the fat is fully dissolved in the milk, thus preventing the fat from being adsorbed on the packaging. The results of homogenization are as follows: fat globules are broken, which is more conducive to human digestion and absorption; Broken fat globules dissolve in milk to give off fat fragrance, which makes the milk taste more rich and mellow; After homogenization, sterilization and other different processing technologies, its nutritional value is not low at all. The quality of "thick" and "light" milk is only different in processing technology, and there is almost no difference in its nutritional composition. You can't judge the quality of milk by its consistency or lightness. There is a more convincing reason that adding thickener, stabilizer or milk powder can make milk look thicker. Main indicators to evaluate the quality of milk The main components of milk are water, fat, protein, lactose and minerals, and the trace components are vitamins, enzymes and gases. After removing water and gas from milk, the remaining substances are called dry milk substances or total milk solids, and skim milk solids refer to the solid content except fat. Milk fat is one of the most important ingredients in milk and dairy products: protein innuendo of milk is one of the most important quality indexes of milk, which is especially important for making raw milk of dairy products such as cheese and yogurt. The product label shall indicate the product type and the solid content of protein, fat and skim milk (or lactose or full-fat solids). Milk is rich in nutrients, and there are almost all kinds of nutrients needed by human body, so milk is called "perfect food". From this point of view, some nutritional defects in milk are really hidden: 1, the iron content in milk is slightly less than that in human milk, even less than the daily nutritional requirements of human body, so we should eat other foods rich in iron. 2. There is no dietary fiber in milk, which is very important for human gastrointestinal function. 3. Taurine plays an important role in human vision, improving immunity and promoting infant brain development, but the content of taurine in fresh milk often cannot meet children's physiological needs. Taurine is often added to formula milk powder. Special milk will cause adverse metabolic reactions to special people. It is reported that 85%-92% of adult Asians have very low intestinal lactase activity. After eating milk, they can't digest and utilize lactose in milk, and often have abdominal distension, bowel sounds and even diarrhea, which shows that lactose is not symptomatic. This metabolic disorder is lifelong and worsens with age. People with normal lactose response will also develop secondary lactose intolerance due to intestinal diseases or infections, but it is usually only temporary. Low lactose liquid milk is another choice for this special population to enjoy milk. Dr. Lu Jiaping from the Technology Development Center of Beijing Sanyuan Food Co., Ltd. said that adding lactase to liquid milk can decompose lactose in milk, so that patients with lactose intolerance can safely drink milk. Ternary low lactose liquid milk is packaged in tetra pak brick, which belongs to ultra-high temperature sterilized milk, and its price is close to that of ordinary ultra-high temperature liquid milk.