According to statistics from the Food and Agriculture Organization of the United Nations in the 1990s, 30% of the world’s food was discarded due to corruption, and at the same time, 300-500 million people in developing countries in Asia, Africa, and Latin America were in a state of hunger. To solve this contradiction, it is crucial to use packaging technology to prevent food spoilage. The preservation packaging of fresh food is an important packaging technology to prevent spoilage and extend the shelf life of food.
As is well known, fresh food can be kept from spoilage for a long time through freezing and refrigeration; Removing moisture to keep food dry can also inhibit the growth of spoilage bacteria in food; Salted or vinegar soaked food is another method of preserving food to prevent spoilage. Preservation film utilizes the certain degree of breathability of the film to induce normal respiration of fresh food cells in the preservation bag by inhaling O2 and excreting CO. Over time, the amount of CO2 in the bag increases due to the respiration of fresh food cells, while O2 decreases. When CO2 reaches 7% or more and O2 is around 2%, the respiration of fresh food in the bag becomes weaker and the cells are in a “hibernation” state. Due to the certain degree of breathability of the preservation bag, the composition of the gas in the bag can be stored at the level of “hibernation” for a long time, thus achieving the function of preservation. The cling film must also have the ability to prevent a large amount of water inside the bag from evaporating and escaping, and to prevent water from aggregating and dripping onto fresh food on the inner layer of the bag. However, the dripping water can cause spoilage and deterioration of fresh food. The cling film should also have a certain degree of self adhesiveness, which can easily wrap food.
