Research On The Development And Mechanism Of Shrimp Bio-preservation Technology

Shrimp is one of the favorite aquatic products of consumers.At present,physical methods,chemical methods and biological methods have been developed for the preservation of shrimp products.The paper is based on the research progress of shrimp preservation technology,developing a new preservative,researching its preservation effect and exploring the preservation mechanism at the molecular level.The main results of the research are shown as follows:(1)Firstly,Flavobacterium B2 was selected as the research object,and the key factors affecting the production of oligosaccharide in algae were selected on the basis of single factor.Secondly,the optimum fermentation process was determined by Box-Behnken Design.The result showed that the key factors and their optimal conditions were pH 8.0,sodium chloride mass concentration 5 g/L,fermentation temperature 35 ?,and the optimal condition for the extraction of alginate oligosaccharide was 17.88%higher than before optimization.(2)Firstly,A single protein with activity was successfully purified by ammonium sulfate fractionation,ion exchange chromatography and gel filtration chromatography.The molecular weight was about 80 KD.Secondly,the optimal conditions for the preparation of alginate oligosaccharide by enzymolysis was studied.After the optimum conditions were determined by single factor experiments,the optimal enzymolysis process was determined by Central Composite Design.The experimental results showed that the optimal experimental conditions were pH 8.4,temperature 31 ?,and the optimal condition for the extraction of alginate oligosaccharide was 64.87%higher than before optimization.(3)Firstly,the preservation effect of alginate oligosaccharide prepared by enzymatic hydrolysis on shrimp was studied.The results showed that the alginate oligosaccharide maintain the texture properties such as hardness,adhesiveness and chewiness of shrimp,and reduce pH,total bacterial count,and K value.The value of freshness index such as total volatile basic nitrogen(TVB-N).Secondly,we investigated whether the addition of tea polyphenol based on alginate oligosaccharide could improve the preservation effect.The results showed that the treatment group added tea polyphenol compared to the alginate oligosaccharide group both in terms of texture characteristics and freshness indicators of shrimp had no change.(4)The optimum formula of the compound preservative was optimized by the orthogonal experiment,and the effect was studied under the best technological conditions.The optimum compound preservative formula was as follows:alginate oligosaccharide 10 g/L,chitosan 10 g/L,and phytic acid 60?L/mL.Under the optimum conditions,the reagent can effectively prolong the storage period of shirmp,and the effect of preservation improved significantly compared with that when the phytic acid used alone.(5)Determination of the antibacterial,antioxidative and polyphenol oxidase(PPO)activities of alginate oligosaccharide,phytic acid and chitosan.The results showed that alginate oligosaccharide and phytic acid had obvious antibacterial effects;Alginate oligosaccharide and chitosan had the strong ABTS free radical scavenging activity.All three substances could effectively inhibit the activity of PPO.(6)The microbial diversity analysis of 16S rDNA intestinal microflora showed that there were significant differences in the abundance of microorganisms in the samples treated with complex,alginate oligosaccharide,and water.Among them,the abundances of the genus Pseudomonas spp.and Shewanella spp.in shrimps were significantly decreased in the abundances of the alginate oligosaccharide and complex.