Dairy sterilization: how about the level of low-temperature sterilized fresh milk? Is the quality of low temperature raw dairy products good?

Fresh milk sterilization can be divided into two simple methods, one is low temperature sterilization, the other is high temperature sterilization, each has its own supporters. Consumers who support low-temperature sterilization believe that fresh milk can retain more nutrition without high-temperature sterilization, while consumers who support high-temperature sterilization believe that fresh milk is easy to go bad, and high-temperature sterilization can ensure hygiene and safety. Experts doubt that low-temperature sterilized fresh milk must have excellent milk source, and there are layers of hurdles to take care of in order to avoid rancidity. As for the difference between nutrients and high-temperature sterilized fresh milk, there is only a gap of about 3%.

Yimei fresh milk, the fourth-largest dairy factory in China, was temporarily removed from the shelves by Costco because consumers reported that the fresh milk turned sour before the expiration of its shelf life. Gao Zhiming, general manager of Yimei, said in a statement on the official website that the products in Costco are sterilized at a temperature of 84 ℃ ±5 degrees to retain more nutrition, but consumers are prone to rancidity and caking if they are stored at different stages of purchase and drinking.

The lower the number of bacteria in the first reborn milk by low temperature sterilization, the better.

Chen Mingru, a professor in the Department of Animal Science and Technology of National Taiwan University, a domestic dairy processing expert, explained that the H.T.S.T quick-temperature sterilization method, commonly known as low-temperature sterilization, is suitable for good quality milk sources. The lower the number of raw bacteria, the better. The domestic standard for the number of raw milk must be less than 100000, but the number of raw milk prepared to be sterilized at low temperature should be as low as 10, 000 or 20, 000, otherwise there will be doubts. Because raw milk still has raw bacteria residue after low temperature sterilization, packed into boxed or canned fresh milk, raw bacteria will continue to grow, and when it grows to a certain extent, fresh milk will spoil. Therefore, in addition to having excellent quality raw milk, the preservation period should not be too long to urge consumers to drink it as soon as possible.

The only way to achieve a very low standard of bacteria is through good farm management, the farm environment and milking equipment should be clean, and cows should also be healthy. once the breasts become inflamed, the number of bacteria and somatic cells in raw milk will soar; how to preserve raw milk in pastures and wait for milk collectors to collect milk is also very important.

At present, there are also many dairy farmers who produce and sell themselves, and a small number of farms use low temperature sterilization, such as dad's fresh milk. according to the actual experience of consumers, they take the bag home after leaving the refrigerator and go home for about half an hour. Fresh milk is at a normal temperature, and then go into the refrigerator after returning home, and there is no experience of fresh milk going bad.

It is better to buy a small bottle of fresh milk than to buy a large bottle and drink it up as soon as possible after opening it.

Another sterilization law of raw milk is high temperature sterilization, that is, U.H.T ultra high temperature sterilization, temperature 125 ℃ to 135 ℃, this is a commonly used way of sterilization in domestic dairy factories, Chen Mingru said, fresh milk made by ultra-high temperature sterilization is not so strict about raw milk, the cold chain and preservation conditions are relatively loose, and you don't have to rush home directly into the cold box after buying fresh milk. The summer temperature in Taiwan is high, so it is more suitable to use high temperature sterilization to produce fresh milk.

Cold chain is an important key to the preservation of fresh milk. Chen Mingru said that after fresh milk is purchased from the factory to the store and then to consumers, it is the key to go into the refrigerator at home and keep the temperature below 7 degrees Celsius, but if the refrigerating device in the store is open and whether the temperature fluctuates, consumers should observe and pay more attention to it when they buy it. After buying it, send it to the refrigerator as soon as possible, and the refrigerated temperature should be lowered, but only if it does not freeze.

If you go to Costco to buy fresh milk, the store is very large. even if the last one takes fresh milk, it will take some time to get to the parking lot when the bill is finished. Chen Mingru suggests that you can use ice cubes and cold bags to keep the fresh milk at a low temperature. The family has a small population, do not buy large bottles, it is recommended to buy less than 1 liter of small bottles, open as soon as possible to drink, otherwise a large bottle of 2-liter or 1-gallon fresh milk, will only increase the risk of rancidity.

There was no significant difference in nutritional composition of fresh milk between the two sterilization methods.

As for the differences in nutrients, Chen Mingru said that there is no significant difference in the nutrients of fresh milk after two kinds of sterilization. The main nutrients of fresh milk are protein and calcium, which will not be destroyed because of U.H.T. Only vitamins A, D, and group B will be oxidized because of high temperature, but these vitamins are not considered to be the main nutrients of fresh milk.