Study On The Effect Of Low Voltage Electrostatic Field On Fresh-keeping Of Litopenaeus Vannamei

In this paper,the chilled Litopenaeus vannamei was taken as the research object,and the low-voltage electrostatic field and refrigerator were used as the preservation medium to explore the difference of the preservation effect of the two on Litopenaeus vannamei under the same temperature(-7?).Through the storage period,achieved the determination of the physical and chemical properties,extracting during storage,achieved the polyphenol oxidase and the enzyme indexes determination and analysis,through high-throughput sequencing low-voltage electrostatic field in the microbial community composition and change analysis,and in order to fully understand the mechanism of preservation of low-voltage electrostatic field,for storage in low voltage electrostatic field,achieved the protein and lipid composition were studied.The main conclusions are as follows:1)The pH value,TVB-N value,cooking loss rate,texture change,color difference,amino acid content,microstructure and sensory score of Litaeus vannamei during storage were determined.The experimental results showed that the sensory scores of Litopenaeus vannamei treated with low voltage electrostatic field were better.The pH value,TVB-N value and cooking loss rate of Litopenaes vannamei were always lower than those of the control group.The texture test showed that the low voltage electrostatic field could also slow down the degradation of protein and better maintain the original taste of shrimp meat.The microstructure of Litopenaeus vannamei was observed by hematoxylin-eosin staining and scanning electron microscopy.It was found that the muscle fiber bundles of Litopenaeus vannamei were more compact and the structure was more complete and smooth in low voltage electrostatic field.The quality of Litopenaeus vannamei can be better maintained by adding low voltage electrostatic field in ordinary refrigerator,and the shelf life of Litopenaeus vannamei can be prolonged,which provides feasible technical conditions for storage and preservation of Litopenaeus vannamei in the future.2)In order to study the effects of low-voltage electrostatic field combined with micro-freezing preservation technology on PPO in Litopenaeus vannamei,the differences in the freezing storage process of Litopenaeus vannamei in low-voltage electrostatic field(treatment group)and non-electrostatic field(control group)were explored.The indexes of enzyme activity,pH,total sulfhydryl group,surface hydrophobicity,total protein and Ca²⁺-ATPase activity were compared and analyzed.SDS-PAGE gel electrophoresis and circular dichromatography were used to investigate the effect of low voltage electrostatic on PPO conformation.The results showed that the activity of PPO enzyme in the treatment group was always lower than that in the control group.At 24 days of storage,the activity of PPO enzyme in the treatment group was 117.5A/(min·m L),while that in the control group was 126A/(min·m L),indicating that the activity of the enzyme could be better inhibited by low voltage electrostatic.The contents of total sulfhydryl,total protein and Ca²⁺-ATPase in the two groups showed a general decreasing trend,but the activities of total sulfhydryl,total protein and Ca²⁺-ATPase in the treatment group decreased slowly,indicating that the low voltage electrostatic can inhibit protein denaturation of PPO.The results of SDS-PAGE showed that the molecular weight of PPO did not change significantly.The results of circular dichromatography and surface hydrophobicity showed that low voltage electrostatic might affect the activity of the enzyme by changing the secondary structure of PPO.3)Illuminamiseq high throughput sequencing technology was used to analyze bacterial diversity and community composition of Litopenaeus vannamei in the control group under normal microfreezing and the treatment group under microfreezing combined with low voltage electrostatic field storage.By Tags and OTU number type analysis,Alpha diversity index analysis,Beta diversity analysis,showed that freezing combined with low-voltage electrostatic field storage can inhibit the growth of microorganisms under the condition of freezing,freezing and reducing bacteria abundance and diversity in combination of low-voltage electrostatic field under the condition of storage,achieved the ordinary freezing conditions,achieved,the impact of the prawn body surface microbial colony is greater.The results showed that the addition of low-voltage electrostatic field in the microfreezing condition could effectively inhibit the growth and reproduction of microorganisms in shrimp,and reduce the spoilage caused by microbial infection.At the same time,micro-freezing and low-voltage electrostatic field preservation can have a synergistic effect,the combination of the two can enhance the preservation effect,which is better than the traditional simple micro-freezing preservation technology.4)In order to further explore the mechanism of keeping fresh in low voltage electrostatic field,we obtained comprehensive protein and lipid information by using absolute quantitative proteomics(i TRAQ)and lipomics of ultra-performance liquid chromatography(UPLC).Through data analysis,it was concluded that the protein integrity and lipid antioxidant capacity of Litopenaeus vannamei stored under the condition of microfreezing combined with low voltage electrostatic field were higher than those stored under normal microfreezing.In proteomics,in treatment group/fresh group in the control group,a total of 57 in the differences in protein,fresh group on the differences in protein bioinformatics analysis,it is concluded that the low voltage electrostatic field treatment can enhance meat,myosin,the stability of plasma protein,help maintain the shrimp protein degeneration resistance,so as to make the freezing condition of low-voltage electrostatic field of storage,marina change smaller shrimp protein.In lipidomics,the peak of phosphatidylethanolamine(PE)was the most abundant,indicating its diversity and high content,followed by the peak of phosphatidylcholine(PC)in the overlap analysis of the total ion flow diagram of the sample.Principal component analysis(PCA)showed that the composition of fatty acids and phospholipids in Litopenaeus vannamei was little affected by microfreezing combined with low voltage electrostatic field storage conditions.The concentration of metal ions,microorganisms and oxygen in the storage environment were analyzed in KEGG functional annotation of differential lipids.It was concluded that microfreezing combined with low voltage electrostatic field had a better ability to slow down lipid oxidation in the muscle tissue of Litopenaeus vannamei stored.