In the entire supply chain from post-harvest to consumers, the loss rate of fruit and vegetable products is as high as 10%-20%. How to reduce the loss of fresh products such as fruits and vegetables, the preservation technology can be said to have contributed. China wax emulsion for fruits and vegetables are suitable.
What is coating preservation technology
Coating is one of the food preservation methods that have emerged in recent years. Pure natural, non-toxic, harmless macromolecular polysaccharide proteins, lipids, etc. are selected as coating agents, which are coated on the fruit surface by dipping, smearing, spraying, etc. , forming a thin transparent film.
This technology can enhance the protective effect of the fruit epidermis, properly cover the skin openings, inhibit respiration, reduce nutrient loss, and prevent spoilage. Since the coating agent is often developed for the storage characteristics of a certain protection object, the functions of different coating agents will also have certain differences. Exchange, and also have antiseptic effects such as bacteriostatic and anti-oxidation.
Common raw materials for coating preservation
Common coating preservation raw materials are mainly polysaccharides, proteins, lipids, etc.
Polysaccharide coating agents mainly include chitosan, konjac glucomannan, starch, sodium alginate, etc., which can be used to protect the ingredients in food from being oxidized. Some polysaccharide coating agents also have strong bacteriostatic and bactericidal functions.
Chitosan is the product of deacetylation of chitin. It has good film-forming properties, bacteriostatic effect, biocompatibility and biodegradation. At present, chitosan has been widely used in the preservation and storage of food due to its natural non-toxic side effects and low cost.
1.2 Konjac Glucomannan
Konjac glucomannan is a renewable natural polymer compound existing in konjac tubers. It has high viscosity, good thickening, gelling, water-holding, film-forming, biocompatibility, and easy paste. It has played an active role in food processing and preservation of agricultural products.
1.3 Sodium alginate
Sodium alginate, also known as sodium alginate, is a natural polysaccharide extracted from brown algae or bacteria. The film-coated preservative made of sodium alginate has gas selective permeability, which can prevent the process of food metabolism, reduce the intensity of cellular respiration and the consumption of nutrients, reduce the formation of reactive oxygen species, reduce membrane lipid peroxidation, and can protect food from The invasion of foreign microorganisms, so as to achieve the purpose of food preservation.
1.4 Starchy substances
When the starch liquid is heated to about 60 degrees, it gelatinizes into a viscous translucent colloidal solution, which can be coated on the surface of fruits and vegetables to form a starch film. Starch has been widely used in the preservation of fruits and vegetables because of its low cost, easy availability and good film-forming properties, and modified starch with various properties can be obtained by different modification methods.
Casein, whey protein, fibrinogen, soy protein, wheat gluten, zein, and chicken protein have all been reported to be processed into edible films.
The lipid film forming materials mainly include beeswax, ancient wax, stearic acid, palmitic acid, etc. Wrapping meat products with fat was widely used earlier to prevent food shrinkage and to block oxygen and moisture. Numerous studies have demonstrated the preservation effect of lipid membranes on frozen or further processed meat and fish products, extending their shelf life and maintaining their original quality.
4) Composite film
Composite coating agent refers to a film made of 2 or 3 main film-forming substances through certain processing. Due to the different properties of various substances, they are complementary in function, so composite coating agent not only retains the film The advantages of each component in the matrix overcome the shortcomings of a single film coating agent, and can meet the needs of different fruits and vegetables for fresh-keeping.
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