When purchasing fresh-keeping boxes or fresh-keeping films, you must pay attention to whether they are marked with specific names or chemical structural formulas. If you only have English names and no Chinese logo products, you should purchase them carefully. At the same time, we must choose products marked with "food use".
Fresh-keeping boxes are mainly made of polyethylene (PE) and polypropylene (PP). The price difference between the two products is not big, but polypropylene (PP) can better prevent the penetration of grease.
When buying cling film, first of all, it is recommended to buy a self-adhesive cling film made of polyethylene (PE), especially when preserving meat, fruits, etc., because PE is the safest in terms of safety . If you want to keep fresh for a long time, it is recommended to choose polyvinylidene chloride (PVDC), because this kind of material has better moisture retention performance, and the longest preservation period among the three materials. The plastic wrap made of polyvinyl chloride (PVC) has good transparency, viscosity, elasticity and low price, so it has become the choice of many people, but it must be noted that it cannot be used for the preservation of oily foods because it is made of poly The resin composed of vinyl chloride resin, plasticizer and anti-aging agent itself is not toxic. However, the main auxiliary materials such as plasticizers and antioxidants added are toxic. The plasticizers in daily-use PVC plastics mainly use dibutyl terephthalate and dioctyl phthalate. These chemicals All are toxic, and the oil in the food can easily dissolve the plasticizer "ethylammonium" in the plastic wrap, which has a great destructive effect on the human body's secretory system and will disrupt the body's hormone metabolism. Lead stearate, an antioxidant for polyvinyl chloride, is also toxic. Lead polyvinyl chloride (PVC) products containing lead salt antioxidants will contact with ethanol, ether and other solvents to precipitate lead. Lead-containing polyvinyl chloride is used as food packaging to meet fritters, fried cakes, fried fish, cooked meat products, cakes and snack foods, it will cause lead molecules to diffuse into the fat, so PVC plastic bags cannot be used Contain oily foods. In addition, it should not be heated in a microwave oven or used at high temperature. Because PVC plastic products will decompose hydrogen chloride gas slowly at a relatively high temperature, such as about 50 ℃, this gas is harmful to the human body, so PVC products should not be used as food packaging.
Range of use
Experiments have shown that 100 grams of chives wrapped with plastic wrap has a vitamin C content of 1.33 milligrams more than 24 hours later and 1.92 milligrams more of rapeseed and lettuce leaves. However, the experimental results of some vegetables are quite different. After storing 100 grams of radish coated with plastic wrap for one day, the vitamin C content decreased by 3.4 mg, and the bean content decreased by 3.8 mg. Apples.
Cooked food, hot food, oily foods, especially meat, should not be stored in plastic wrap. Experts pointed out that after these foods are in contact with the plastic wrap, it is easy to volatilize the chemical components contained in their materials and dissolve them into the food, which is harmful to health. Most of the cling film sold on the market is made of vinyl masterbatch as raw materials, as is commonly used in plastic bags. Some plastic wrap materials are polyethylene (PE for short), which does not contain plasticizers and is relatively safe to use; some materials are polyvinyl chloride (PVC for short), which often incorporate stabilizers and lubricants , Auxiliary processing agent and other raw materials are harmful to human body. Therefore, we must be cautious in choosing.