Research progress of the hottest edible packaging

Research progress of edible packaging film (Part 2)

2.3 lipid film

its forming materials such as beeswax, ancient wax, stearic acid, palmitic acid, etc. they have the characteristics of weak polarity and easy to form a dense structure, and the formed film has a strong water resistance ability. However, due to the low strength of the film formed by lipids alone, it rarely acts alone, and usually forms a composite film combined with proteins and polysaccharides

2.4 composite membranes

usually take lipids as water blocking components, while proteins or polysaccharides play their own barrier properties and act as lipid supporting media to maintain the good integrity of the membrane. Through such a specific combination, edible membranes have wider functionality and wider application. There are two ways to form composite membrane: one is coating method, which is to coat the molten lipid on the formed polysaccharide membrane to form a double-layer composite membrane; the other is that the lipid and polysaccharide are miscible in the solvent, and certain emulsifier can be added to emulsify it evenly, and then dry it to form a membrane. This method is called emulsification method

in the aspect of composite membrane, some people have studied the performance of the membrane formed by the composite membrane of lipids and whey protein. The results show that the WVP of the emulsified membrane formed by beeswax and milk fat and whey protein is lower than that of the membrane made of carnauba wax and candela wax. Reducing the size of fat particles and making them evenly distributed can increase the moisture and gas resistance of the membrane, WVP of the composite membrane made by casting zein fatty acid solution on methylcellulose decreases with the increase of fatty acid content The interaction between soybean protein and polysaccharide can maintain or improve its solubility and emulsification, and their complexes show better film-forming property and membrane stability in water. The study of methyl cellulose and stearic acid composite membrane shows that by increasing the volume of hard fatty acid fraction to 22%, the water vapor permeability of methyl fiber and stearic acid composite will be significantly reduced

3 application in the food industry

3.1 application in the preservation of fruits and vegetables

British scientists have developed an edible film preservative, which is made from the polyester of sucrose, starch and fatty acids upstream for many times. It is applied to the surface of citrus, apple, watermelon, banana, tomato and other fruits and vegetables by spraying, brushing or dipping, so as to prolong the preservation period of fruits and vegetables. The N, O-carboxymethyl deacetylated chitosan preservative developed in Canada can prolong the fresh-keeping period of fruits and vegetables with 0.7% - 2% NOCC solution. Many studies have been done on the application of chitosan in the fresh-keeping of fruits and vegetables in China, such as longan (at 2 ℃, 90%rh) for 30 days; The shelf life of litchi was extended to 3 days at 33 ~ 34 ℃; Strawberries can be stored for 5 days at room temperature, etc. Using konjak mannan solution to preserve longan, stored at 3 ℃ for 60 days, the good fruit rate is nearly 90%, the weight loss rate is about 2%, and the shelf life of storage period is prolonged. The Edible Preservative we developed can prolong the fresh-keeping period of strawberries at room temperature by 2 ~ 3 times. In terms of fresh-keeping of cut fruits and vegetables, a food company in the United States uses cheese and acetyl monoglyceride extracted from vegetable oil to make a film, and sticks it on the surface of cut fruits and vegetables, which can prevent dehydration, browning and microbial invasion of fruits and vegetables, so that cut fruits and vegetables can also remain fresh for a long time. The U.S. patent all-round fresh-keeping film solution has been produced, which is mainly used for the fresh-keeping of fruits. It can not only prevent water from fading, inhibit bacterial reproduction, but also prevent fruit from shrinking and maintain the texture of pulp unchanged

3.2 application in the processing and preservation of meat products

in the processing and preservation of meat products, collagen film is the most successful example of industrial application. In sausage production, collagen film has largely replaced natural casings (except those larger sausages need thicker casings). In addition, soy protein film can also be used to produce casings and water-soluble packaging bags. Experiments have shown that wrapping meat products with collagen can reduce the long-term loss of juice, color changes and fat oxidation, thus improving the quality of preserved meat products. For example, coating frozen diced beef with collagen can reduce the loss of diced beef during frozen storage, and the loss of juice after thawing is also reduced. The UK has launched a new technology to preserve food by using trehalose, which is used to preserve meat. It can keep the vitamins contained in meat intact, and its color, taste, aroma and nutritional composition have not changed, which is no worse than fresh food. Whey protein film coated on salmon can reduce the peroxide value during frozen storage and improve the preservation quality

3.3 application in fried foods

among the popular ready to eat foods, the one with large output is deep fried food, K Ｉ. Holownia et al. Used hydroxypropyl methyl cellulose and methyl cellulose film to study fried chicken strips and their fried oil. It was found that after using edible film, the free fatty acid content of fried oil was reduced by 50%, and the color value of lbvibond was also reduced by 25%. At the same time, it also reduced the oil absorption rate, thereby prolonging the service life of fried oil. It can be seen that choosing appropriate film-forming agent to pre coat fried food can reduce the oil consumption of products and prolong the service life of oil. Coating fried food with gellan gum can reduce the oil absorption rate by 35% - 63%, such as fish fillets can reduce the oil absorption rate by 63%, potato chips can reduce the oil absorption rate by 60%

3.4 application in baking products

coating chitosan or zein film solution on the surface of bread can prevent bread from drying out due to water loss. Using zein based film can prolong the shelf life of Pecan from 1 month to 3 months (70, Rh50%). Whey protein film coated on the surface of roasted peanuts can significantly reduce the absorption of hypoxia and reduce the deterioration of peanuts Application in the candy industry in the candy industry, for the production of chocolate and surface polished candy, due to the increased restrictions on the diffusion of volatile components, it is necessary to replace the commonly used coating agent containing volatile organic components with water-soluble additives. Water soluble whey protein has the potential to replace alcohol soluble shellac and zein. The coating agent based on water-soluble whey protein forms a water-insoluble, tough, transparent and scrapeable coating agent

3.5 application in food packaging

it is certain that the cereal film developed by the first 23 intelligent manufacturing system solution suppliers at cremson University in South Carolina, the United States, takes corn, soybeans, wheat as raw materials and is made into paper form, which can be used for the packaging of sausage and other food, and can be used for poultry consumption or as fertilizer after use. The collagen film developed by "Natick" in the United States is made of animal collagen, which has the characteristics of high strength, good water resistance and good performance of isolating water vapor. It is soluble and edible when thawing and cooking, and it will not change its flavor when used to pack meat food. The film developed by Mitsubishi man-made fiber company in Japan, ③. The clamping sample is made of natural polysaccharides extracted from red algae as raw materials, which is translucent, tough and heat sealing. In addition, there are some edible protein films, such as milk protein film, casein white film, corn gliadin film, and the newly developed edible packaging with antibacterial function, such as adding bacteriostatic components such as lysozyme to corn gliadin or soybean protein single film, which can control the growth of pathogenic bacteria in food and food corruption caused by microorganisms. A water-resistant protein film developed by the Japanese Institute of agriculture, forestry, fisheries and food is a new packaging material that can replace foam polystyrene, and its strength is equivalent to the synthetic film used for ordinary food packaging. Japan has also introduced an edible packaging paper with soybean dregs as raw materials, which is most suitable for the packaging of seasoning fast-food noodles. It is characterized by dissolving in hot water without tearing the package. It is not only convenient, but also has certain nutritional value. China has developed corn starch sodium alginate or chitosan composite packaging film (paper) for the inner packaging of preserved fruits, cakes, instant noodles, soup and many other convenient foods. Its main characteristics are high tensile strength and elongation, as well as good water resistance

4. Prospect

many advantages of edible film make it an irreversible trend to replace ordinary plastics. It will cause a revolution in packaging and has great development prospects. However, there are many studies on it all over the world, and many practical problems have not been solved and have not been widely used. However, with the development of science and technology, such problems will be solved, Edible film will eventually replace ordinary plastic packaging

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