In the process of meat production and processing, there are always two cooking processes, namely high temperature and high pressure sterilization and low temperature and normal pressure sterilization. Low temperature sterilization of meat because of the low heating temperature, the fiber of the meat is not destroyed, so the taste is fresh and tender, a variety of nutrients preserved better; but because it only kills the pathogenic bacteria, there are still a large number of spoilage bacteria, not only the shelf life is short, and easily cause the loss in the field of circulation. High temperature sterilization of meat products due to high heating temperature and excessive shrinkage of meat fiber, taste is not as low temperature sterilization products, but because it kills all bacteria, eliminating the internal cause of corruption, can greatly extend the shelf life.

High temperature sterilization of meat such as high barrier packaging materials, not only at room temperature storage shelf life is longer, and transportation, storage, sales are very convenient, very suitable for the consumer demand of modern society. Therefore, vigorously developing the production of meat products that are resistant to storage at room temperature is an important product development direction for the meat industry. The packaging industry conforms to this development trend and makes a difference, which can not only meet the needs of the food industry, but also win a broad market for itself.

It is understood that the earliest packaging that can store meat at room temperature is canned, which is made of tinplate, and later uses glass bottles as outer packaging. Tinplate and glass bottles have high temperature cooking resistance and high barrier properties, so the shelf life of canned food can reach more than 2 years. However, because tinplate cans and glass bottles are hard packaging containers, large in size and heavy in quality, the chemical resistance of tinplate is not good, especially when loaded into acidic food, metal ions are easy to precipitate, affecting the flavor of food.

In the 1960 s, the United States in order to solve the aerospace food packaging and aluminum-plastic composite film, with its packaging meat, through high temperature and high pressure sterilization, can be stored at room temperature, shelf life of up to 1 years. The role of aluminum-plastic composite film is similar to that of cans, soft and light, so it is named soft cans. Store meat with a long shelf life at room temperature, such as the use of hard packaging containers, or the use of tinplate cans and glass bottles; such as the use of flexible packaging, almost all of the use of aluminum-plastic composite film.

The aluminum-plastic composite film is a laminated composite multilayer film, generally three layers, and the typical structure is surface layer/adhesive/aluminum foil/adhesive/heat seal layer (CPP). The advantages of the packaging film are beautiful appearance and good mechanical properties, high barrier properties, high temperature cooking resistance and excellent hygiene, and light weight, soft, so it is widely used in various food packaging. But there are also some defects, such as aluminum foil texture is hard and brittle, and the flexibility is not very good compared with plastic film.

In order to extend the shelf life of meat, high temperature cooking meat are vacuum skin packaging. Aluminum foil composite materials in the vacuum, because the flexibility of the aluminum foil is not enough, it is difficult to stick on the contents, easy to cause the air in the packaging bag is not clean, affecting the preservation of food. Therefore, the thickness of aluminum foil for meat packaging should not be too high. However, because its barrier property depends on the thickness and processing level, when the thickness is small, it is easy to have a large number of pinholes, so the thickness of aluminum foil can not be too thin for the packaging of storage-resistant meat products. If the aluminum foil is too thin, the aluminum foil composite film will form many wrinkles after vacuuming, which will easily lead to cracks and loss of barrier property. Therefore, the thickness, barrier property and flexibility of aluminum foil are always the three contradictions that plague the application of aluminum foil composite film.

From the market point of view, aluminum foil composite film packaging food because of opaque so that consumers can not see the color and shape of the contents, is not conducive to consumers to buy, plus some manufacturers use aluminum-plastic composite film opaque to cover up the defects of the product, and even fraud, harm consumers. Therefore, most consumers choose transparent packaging instead of opaque aluminum-plastic composite film packaging, resulting in poor sales of such packaged food. Aluminum-plastic composite packaging can not be heated by microwave, and the price is more expensive than plastic film, which affects the application of aluminum-plastic composite film. Therefore, the food processing industry has been hoping that the packaging material process can provide a barrier similar to the aluminum-plastic composite film, but both transparent, but also high temperature cooking packaging materials to replace the aluminum-plastic composite film.

Among the plastics used in industry, only PVDC plastic film has both high barrier properties similar to aluminum foil and high temperature cooking resistance. For a long time, people hope to use PVDC plastic as the middle layer made of composite film, become transparent and high temperature resistant cooking, but also has similar high barrier properties of aluminum foil high temperature resistant food packaging film. However, PVDC plastic is a kind of performance, extremely difficult to process plastic, it is used as an intermediate layer to make composite film there are many difficulties.

PVDC plastic film was made in 1938 by a special blown film process by scientists from the American State Road Chemical Company. Since the 1950 s, it has been used as a casing for high-temperature cooked meat enema. The high-temperature sterilized meat products packaged with it are stored at room temperature and have a shelf life of more than 6 months. However, PVDC film can only be heat-sealed by high-frequency dielectric heating, and cannot be heat-sealed by the commonly used resistance heating method, so for many years PVDC film is only used as casing, and cannot be made into packaging bags.

In recent years, experimental studies have shown that PVDC films can be directly compounded into composite membranes without any treatment by solvent-free compounding. The composite film in the high temperature cooking the whole film shape will not be destroyed, always keep smooth, combined closely, mixed into one, can meet the needs of high temperature cooking food packaging. The PVDC laminated composite high temperature cooking food packaging film made by this method has been affirmed after it was put on the market, proving that it is a food packaging film with three characteristics of high transparency, high barrier and high temperature cooking temperature after the aluminum-plastic composite film, and its performance index has reached the level.

Compared with aluminum-plastic composite film, PVDC laminated composite film has similar barrier properties, is fully transparent and softer. It is used for vacuum skin packaging of meat food. The air in the bag is pumped very clean, which is more conducive to the preservation of meat food and can be heated by microwave. The price is only 70% ~ 80% of aluminum foil composite film, so it can replace the application of aluminum-plastic composite film in a considerable range.

The research and development of polyvinyl alcohol (PVA) coated BOPP barrier film has brought new hope for food packaging. This kind of barrier film has both oxygen barrier and water vapor barrier, the polymer does not contain toxic elements, and the transfer of toxic elements will not occur during use. The barrier material PVA is a microbial synthetic polymer material with a dual degradation mechanism of hydrolysis and biodegradation, which can be degraded into water and carbon dioxide. It is also a high-performance environment-friendly material and can replace PVDC coating film in many aspects. It is mainly used for meat food, quick-frozen convenience food and non-food flavor preservation (such as insect repellent) packaging, etc., has a broad application prospects.