Study On The Effect Of Fish Skin Collagen Compound Edible Antibacterial Coating On Red Porgy Preservation

Aquatic products are high in water,protein and fat.During storage,the quality of aquatic products tends to decline due to endogenous chemical and enzymatic reactions,as well as the role of spoilage and pathogenic microorganisms.Despite improved production facilities and effective process control procedures,the number of foodborne diseases associated with aquatic products has been increasing.Edible film is made of natural edible materials,basically divided into three categories:polysaccharides,proteins,lipids.It can improve the quality of fresh frozen products by delaying the growth of microorganisms,reducing lipid oxidation,reducing water loss,and can be used as a carrier of food additives,such as adding antibacterial agent,antioxidant,thickening agent,to improve the function of edible film,so as to extend the shelf life of food.Compared with synthetic packaging,biodegradable,biocompatible and non-polluting edible membranes are more popular among people.In this study,collagen was extracted from surplus blue shark skin resources,and edible coating was prepared for fish preservation by combining with chitosan with strong bacteriostasis ability,and the preservation mechanism of shelf-life of cold storage red porgy was discussed.This not only maximizes the use of limited resources,but also provides a theoretical basis for the development of edible membranes.The conclusions are as follows:Pepsin soluble collagen?PSC?was extracted from the skin of blue shark?Prionace glauca?and its structure and properties were characterized.The extraction rate of PSC was 8.74±0.62%?wet base?,the content of hydroxyproline?Hyp?was 8.07±0.20%,and the content of collagen was 64.58±1.62%.According to SDS-page analysis,PSC is composed of?₁ chain?₂ chain and?chain,belonging to type I collagen.By amino acid composition analysis result,the highest levels of blue sharkskin PSC is glycine?310.22residuals/1000 amino acid residues?,followed by alanine?Ala?,proline?Pro?,hydroxyproline?Hyp?,methionine?Met?and histidine?His?,cysteine?Cys?and tyrosine?Tyr?,its amino acid composition is consistent with that of typical fish collagen.The imino acid content of PSC is 185.98 residues/1000 amino acid residues,which is higher than that of common fish collagen.The results show that the PSC of blue sharkskin obtained in this experiment is type I collagen with high content of imino acids,which is expected to be widely used in the market.It is pointed out that edible collagen chitosan coating has the characteristics of biodegradable,biocompatible and economical,which can meet the requirements of aquatic product quality and storage time.Red porgy is rich in protein,fat and various trace elements,and delicious,but due to high water,high protein is easy to be used by microorganisms and spoilage.Therefore,it is very important to extend the shelf life of sea bream by edible coating.The effects of PSC and chitosan on the fillet quality of red porgy?Pagrus major?under storage conditions of 4?were studied by using the total number of colonies,total volatile basic nitrogen?TVB-N?,thiobarbital acid?TBA?,p H,K value,drip loss percent and sensory evaluation score as indicators.The results showed that 1%chitosan coating with 0-0.8%PSC could significantly improve most deterioration indexes.The addition of 0.8%PSC to 1%chitosan coating had the best effect on the total number of colonies,loss of water,K value and sensory evaluation,but other indexes had no obvious dependence on PSC concentration.The results showed that the best coating formula was 1%chitosan solution containing 0.8%PSC,and a better and more effective edible coating formula was obtained to prolong the shelf life of red porgy fillets.The fourth chapter from the perspective of protein denaturation and degradation during storage,the main protein in fish muscle,myofibrillar protein,using the protein content,total sulphur content,Ca²⁺-ATPase activity and surface hydrophobicity as an index,explore the blue shark references on red porgy fish protein-chitosan coating preservation processing under the regularity of change and the degradation of protein properties.The results showed that with the extension of storage time,the contents of myofibrillar protein,total sulfhydryl and Ca²⁺-ATPase all decreased,while the surface hydrophobicity increased.Compared with the non-coated group,collagen-chitosan coating treatment can delay the exposure of hydrophobic groups and the oxidation of sulfhydryl groups in myofibrillar protein,maintain the activity of Ca²⁺-ATPase,and reduce its denaturation degree.The results showed that collagen-chitosan coating could inhibit the degradation of fish protein,maintain its high quality and prolong its shelf life.This study preliminarily revealed the preservation mechanism of blue shark skin collagen protein-chitosan coating,which is expected to provide new ideas and scientific basis for the development and application of edible coating or film.