In cold weather, many milk drinkers like to heat their milk before drinking, but there is a saying circulated on the Internet that drinking after heating the milk in bags will not only lead to the loss of milk nutrition, but also lead to the precipitation of heavy metal aluminum in the outer packaging, which is harmful to health. Does it really cause nutrient loss if the milk is heated and drank? Does the heavy metal aluminium in the outer packing really cause health hazards? How to heat milk for people who want to drink hot milk in winter? The reporter interviewed Tang Gaoqi, associate professor of Food Engineering College of Henan Agricultural Vocational College.
Bagged milk belongs to UHT milk, Tang said. After sterilization for 4-15 seconds at 135℃-150℃, the possible growth of microorganisms and spores can be destroyed. At the same time, this heat treatment will cause low damage to vitamins in milk, but the protein and calcium in milk will not be destroyed, so UHT milk retains most of the nutrition of fresh milk. Milk heated at home usually does not exceed 100 ℃. Compared with UHT sterilization, this low temperature has little damage to the nutritional components of milk. Therefore, after a short time of heating, the nutritional loss of milk will not occur.
So, will the heavy metal aluminium precipitate from the outer package after heating, which is harmful to health?
First, Aluminum is not a heavy metal, but a silver-white light metal. Aluminum can cause chronic poisoning by accumulating in the body, Tang said. But the packaging of milk in bags is a kind of "green" material made of paper, aluminum foil and polyethylene. The melting point of polyethylene is generally above 120 C, which is much higher than the boiling point of water. Therefore, it is impossible for polyethylene layer to break down and melt in the process of boiling, and aluminum foil can not precipitate metal aluminum. Therefore, it is groundless to say that heated milk in bags will cause the precipitation of heavy metal aluminum in the package and endanger health.
Bagged milk can be drunk directly, but after winter or fresh milk from the refrigerator because of the low temperature, it tastes better to heat it properly before drinking. Tang Gouqi suggests that the milk in the bag be immersed directly in hot water not higher than 90 C for a period of time, or that the milk in the bag be opened and poured into the available container for the microwave oven and heated in the microwave oven for 1 to 2 minutes.
