Cold meat packaging preservation technology, you know a few?

1 Characteristics of cold meat

Cold meat refers to the rapid cooling of carcasses after slaughter of livestock and poultry, so that carcass temperature is reduced to 0 to 4 °C within 24 hours , and remains within this temperature range during subsequent processing, distribution and sales. meat. Compared with hot meat, cold meat is always in a cool environment. Most of the microorganisms are inhibited from growth and reproduction to ensure the health and safety of meat. Compared with frozen meat, cold meat has less loss of juice and is soft and elastic. Taste delicious, high nutritional value and other advantages. China's famous meat product company, Henan Double Exchange, first sells cold meat as a chain industry, and imports foreign meat marketing models of “cold chain production, cold chain transportation, cold chain sales, and chain operation” to the domestic market and establish meat chain stores. Nanjing Yurun and Shandong Jinhao followed, and various cold meat chains spread all over the streets of the city. However, cold meat is sold in a freezer at 0 to 4 °C . Its temperature can only inhibit the growth and reproduction of microorganisms and the activity of enzymes to a certain extent, but it cannot stop its activities. The shelf life of this refrigerated packaged meat is only For 3-4 days, the problem of sanitary quality and safety of fresh meat still exists. How to extend the shelf life of cooling meat has become a problem that needs to be solved urgently in the cooling meat processing industry. The use of reasonable and effective preservation technology is an indispensable step in ensuring high quality cold meat. At present, the advanced cold meat fresh-keeping packaging technologies mainly include vacuum shrink packaging, thermoforming packaging, vacuum skin packaging, and modified atmosphere packaging.

2 advanced cold meat packaging technology

2.1 Vacuum shrink packaging

Vacuum shrink packaging has been widely used in developed countries, of which the United States is the world's largest consumer of shrink bags; Australia, New Zealand, and Europe also have larger markets, and Asia, relatively speaking, has a smaller consumer market. The overall market for shrink bags is between 100 and 15 billion bags or between 1 and 2 billion US dollars.

When the vacuum shrink bag is used for cold meat packaging, the inner package is vacuum-sealed and put into hot water or hot aisle. The plastic bag shrinks into the original shape of the meat piece and becomes the second layer of meat. Shrinkage reduces excess material outside the package, making the package more tightly and aesthetically pleasing, increasing the attractiveness of meat sales; shrinking eliminates wrinkles in the packaging bag and capillary water absorption resulting from it, thereby minimizing blood flow from the meat Exudation. Based on the shrinkage effect, the thickness of the barrier plastic bag film is thus increased, enhancing its wear resistance and barrier properties. Through vacuum shrink packaging, cold meat can be stored for up to one month after slaughter. The shrink film is prepared by a double bubble co-extrusion method. The raw material resin is melted and extruded through the extruder to extrude the first film bubble. The extruded film tube is quickly cooled by a vacuum sizing and then pressed by a splint, and pulled by a traction roller. After drying, the flattened material belt penetrates into the EB device and enters the preheated water tank for heating after being irradiated, and is formed into a second bubble by the second inflation, and finally traction and winding to form a film. The product shrinkage is about 35 to 45%, and the thickness range is 50 to 90 μm. The heat shrinkable bag made of film is generally tubular. The sealing of the shrinking bag is different from the straight sealing of the vacuum bag. It is an arc-shaped seal so that the shrinkage of the bag is maximized after the heat shrinking. No leftover material left.

2.2 Thermoforming packaging

In the early 1990s, the world leader in functional packaging materials such as Cryovac, Curwood, and Wipak took the lead in entering the market with brand and technology advantages and dug the first pot of gold. In China, after more than ten years of cultivation of thermoformed packaging materials, the market scale has developed rapidly. The main processes adopted for thermoformed packaging materials are casting and down-extruded water-cooled processes. The casting process is relatively mature, but the cooling efficiency is low, the appearance is stripe, and the yield is low; while the down-extruded water-cooling process With the advantages of high tensile strength, high production efficiency, and soft, transparent and easy-to-mold film, it is a fast-growing high technology in recent years and will also be the mainstream technology for future production and development.

Thin-film thermoforming is a method in which the film produced by the above process is re-softened by heating, and the film is molded into a desired shape of the packaging container by means of a suitable mold by means of the pressure difference between the two surfaces of the film or the mechanical pressure on one side. Thermoformed packaging has the following advantages: excellent molding performance, high transparency, safe and sanitary in circulation, high degree of automation, production capacity increased by several dozen times than manual packaging.

2.3 Vacuum Skin Packaging

Vacuum skin packaging is a novel commodity packaging technology widely used in the international food packaging industry. It is mainly used for the packaging of fresh meat, fish, aquatic products, cooked meat products, cured products, sliced ​​sausages, and sushi. After food packaging, it not only displays good quality, but also has a long shelf life and is easy to eat. Vacuum skin packaging mainly consists of a substrate tray and a plastic cover film. The process of body-packaging is: the packaged product is placed in a tray, so that the special body-covered plastic cover film covering the product is closely attached to the surface of the product under the action of heating and vacuuming, and is sealed with the substrate tray. The substrate trays for vacuum skin packaging require good tensile properties, good barrier properties, high strength, and strong pressure resistance. The structure is generally a high barrier PVC or PET composite sheet, such as PVC/PE/EVOH/PE, VMPET / PE / EVOH / PE, etc.; body-fitting plastic cover film is generally heated to the viscous flow of multi-layer high barrier coextruded material, the inner layer of hot sticky, good elasticity Surlyn and EVA resin. Different from stretch-type packaging, vacuum-body packaging does not require any mold, and products with different sizes and different shapes can achieve the effect of close to food and sealed packaging through special transparent cover film, which is convenient, economical and efficient. .

2.4 Modified atmosphere packaging

Atmosphere preservation is the use of packaging materials with gas barrier properties packaging food, according to the actual needs of customers will be a certain proportion of O2 + CO2 + N2, N2 + CO2, O2 + CO2 mixed gas into the package, thus inhibiting the growth of microorganisms and Breeding, extending the purpose of the preservation period, thereby prolonging the shelf life of food and enhancing the value of food. CO2 mainly inhibits the growth of bacteria and fungi, especially in the early stage of bacterial reproduction, the best antibacterial effect is at low temperature and 20% to 30% concentration; N2 mainly prevents oxidative rancidity and inhibits the growth of mold; O2 is mainly oxygenated muscle red The protein keeps the meat in bright red color and inhibits the growth of anaerobic bacteria.

Whether or not cold-meat can be kept in an initial atmosphere after a certain period of time, depending on the choice of packaging materials used, is therefore a critical aspect of the selection of packaging materials. The following are optional packages. Material should pay attention to the problem: 1) According to the preservation requirements of cold meat, requires the use of low permeability or high barrier film and packaging. In order to reduce the replacement of gases in the package through the film and the gas in the atmosphere; 2) The cover film should have anti-fogging properties and high light transmittance. If the cover film does not have anti-fog properties and high light transmittance, the appearance of the product will be damaged. Affect sales.

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