The freshness preservation effect of fish products

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The fresh-keeping effect of fish products with reasonable packaging is enhanced

fish have more bacteria in vivo and in vitro, but they contain less natural immune elements. The enzymes in fish have the function of decomposing proteins, resulting in the softening of muscle tissue and the decline of freshness. When the decomposition products reach a certain level, fish will also emit odor, and provide favorable conditions for the further breeding, development and reproduction of bacteria. In addition, fish meat is easily oxidized, resulting in deterioration, discoloration or discoloration of meat. For long-term storage or long-distance sales, fish products need quick freezing and refrigeration. If quick freezing, ice coating and cold storage are appropriate, fish products can be kept fresh for half a year to about a year. However, it is not ideal to preserve fish products only by freezing and cold storage. If it is properly packaged, it can get twice the result with half the effort

the fish tissue is inherently fragile. After freezing, the fish tissue will be damaged to a certain extent. If it is subjected to excessive stamping, it will also break the fish body and further damage the fish tissue, which not only affects the appearance, but also the meat quality of the damaged part is easy to deteriorate and affect eating. At the same time, bacteria are easy to breed and multiply in the damaged part during thawing. Obviously, the use of rigid packaging containers that are not damaged and collapse can prevent fish production from various mechanical damage during transportation and handling, so as to maintain its original shape and quality. To this end, the packaging container should be filled with fish products to ensure that during transportation and handling, each power line is not connected to collide with each other

fish not only loses water during freezing, but also loses water due to the sublimation of fine ice crystals on the surface of fish during refrigeration, which will continuously reduce the weight and freshness of fish. At the same time, as the water evaporation on the surface of the fish continues to deepen, a certain thickness of sponge layer will be formed from the outside to the inside, making the fish lose its original taste and nutrients. Therefore, many cities have tried to use permeable concrete sealed packaging in parking lots and non traffic congested roads with packaging materials that can block water vapor, which can prevent the water loss of fish meat in the process of freezing, refrigeration and sales, so as to maintain its original freshness. It is worth noting that there is excess space between the frozen fish products in the package, and the water in the fish body is easy to evaporate, which dehydrates the fish meat, and there is frost inside the package. Therefore, the gap inside the packaging container should be minimized. If packed in plastic film bags, keep the film close to the fish products

fish products contain unsaturated fatty acids, some of which are high in content. It is a two-dimensional crystal composed of closely packed carbon atoms. When it is oxidized, the fish will turn brown and taste stale. Although some anti oxidants can be added during the ice coating treatment to prevent the oxidation of unsaturated fatty acids in fish meat, it will have certain side effects on meat quality. Then, if vacuum packaging is used, better fresh-keeping effect can be achieved. Since vacuum packaging needs to extract the air from the packaging container, it can make the plastic thin. Since the plastic restriction order was implemented on June 1st, 2008, the film bag is close to the fish products, which is very beneficial to reduce the packaging volume and internal gap. In addition, vacuum packaging must be made of packaging materials with low oxygen permeability, and the packaging container must be tightly sealed to prevent oxygen outside the package from penetrating into the package

in artificial air, it can also effectively prevent the oxidation of fish products and inhibit the development and reproduction of bacteria. The so-called artificial air is the air that increases the content of carbon dioxide or nitrogen in the air. If fish products are placed in artificial air with a carbon dioxide concentration of 10%, because of its relatively low oxygen content, it can not only improve the effect of low-temperature refrigeration, but also have a good fresh-keeping effect at room temperature. The realization of artificial air environment in cold storage requires large-scale air conditioning equipment, and the operation cost is high. It is relatively simple to realize air conditioning in the package. Only an inflatable packaging machine can extract part of the air in the package, and then fill it with one or more protective gases. In this way, the quality of fish products can be effectively protected in the process of refrigeration or sales

UV can promote the oxidation of fish products. For example, sunlight and light contain UV components and will heat up fish meat. These adverse effects are particularly significant when fish products are displayed in refrigerated display cabinets. Therefore, opaque materials can be used in the sales packaging of fish products to prevent the invasion of ultraviolet rays. In addition, printing ink can prevent 90% of ultraviolet rays from passing through, so printing more pictures and texts with ink on the surface of transparent materials can also play a role in shading

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