It is understood that the vast majority of plastic wrap sold on the market at present, like common plastic bags, are made of ethylene masterbatch. According to the different types of ethylene masterbatch, plastic wrap can be divided into three categories.
The first is polyethylene, or PE for short. This material is mainly used for food packaging, such as this film for fruits and vegetables we usually buy, including semi-finished products bought in supermarkets. Then the second one is called PVC, which can also be used for food packaging, but it has a certain impact on human safety; The third type is polyvinylidene chloride (PVDC), which is mainly used for packaging cooked food, ham and other products.
Experts said that among the three kinds of plastic wrap, PE and PVDC are safe for human body and can be used safely. But PVC cling film is more harmful to human body.
Physically speaking, plastic wrap has moderate oxygen permeability and moisture permeability, which can adjust the oxygen content and water content around the fresh-keeping products and block the dust in the air, thus prolonging the fresh-keeping period of food. Therefore, it is necessary to choose different plastic wrap for different foods.
The plastic wrap on the market now can be roughly divided into two categories: one is ordinary plastic wrap, which is suitable for refrigerator preservation; One is microwave oven cling film, which can be used for both refrigerator preservation and microwave oven. The latter plastic wrap is far superior to ordinary plastic wrap in heat resistance and non-toxicity. Therefore, consumers should pay special attention to the choice of use and use it separately.
In addition, when using microwave plastic wrap, you should also pay attention to:
1. When oily food is heated, the plastic wrap should be isolated from the food to avoid direct contact with the food. Because when heating food, the cooking oil may reach a very high temperature, which will damage the plastic wrap and stick to the food.
2. When heating food, cover the container with plastic wrap, and then use a toothpick and other needles to make a few small holes in the plastic wrap to facilitate the evaporation of water and prevent the plastic wrap from bursting due to gas expansion.
3. The maximum heat-resistant temperature marked by different brands of plastic wrap is different, and some of them are about 10℃. When the temperature in the microwave oven is high, it will generally reach about 1 10℃. When heating is needed for a long time, you can pay attention to the choice of plastic wrap with high heat resistance.
● How to distinguish PVC from PE?
The transparency, ductility and viscosity of PVC cling film are better than PE cling film. When PVC cling film is on fire, the flame is black, smoky and pungent, and will not drip oil, and will automatically go out after leaving the fire source. When PE cling film burns, the flame is yellow, tasteless and dripping with oil, and it can continue to burn after leaving the fire source. "If the label is made of PVC or the label is unknown, consumers are advised to be cautious." A packaging expert said.