Study On Metal Content Analysis And Quality Guarantee Technology Of Mussel(Mytilus Edulis)

Frozen storage is the most important processing and storage method of mussels.However,in the process of frozen storage,the quality of shellfish products is often degraded due to physical damage of ice crystals,microbial contamination and muscle protein denaturation,which seriously affects its original physical and chemical quality.In addition,the problem of excessive heavy metals in mussels is also one of the focuses of shellfish products at home and abroad.Therefore,the content and distribution of heavy metals in mussels,the dominant species in frozen mussels,and how to maintain and extend the shelf life of frozen mussel meat are the key to the research on the quality and safety control of shellfish products.In the paper,the content of heavy metals in mussel samples from 8 cities along the coast of China was investigated,and the microbial flora composition of mussels attached to different mussels was analyzed in order to suppress the microbes on the surface of frozen mussels.To explore the guarantee effect of composite glazing and low-temperature vacuum treatment technology on mussel quality,and provide technical reference for quality assurance and quality safety of mussel products.The main research contents are as follows:1.The contents of Cd,As,Hg,Cu and Pb in mussels from 8 coastal cities were analyzed.It was found that the heavy metals in the digestive glands and cockroaches of mussels were the most concentrated,such as Cd,As,Hg and Pb.It can be preliminarily judged that such heavy metals enter the mussels through the food pathway and are enriched;B is mainly enriched in the sputum tissue,and it may be that B enters the mussel through the respiratory adsorption mechanism;Cu is mainly enriched in the gonads,while the content of heavy metals in the tentacles is low.This indicates that different tissues of mussels have different enrichment abilities for different elements,and their absorption and enrichment pathways are also different.In addition,from the perspective of different sea areas,the sea areas with heavy mussel pollution are Bohai>East China Sea>South China Sea.The Cd content in some sea areas is about 30 times higher than the national limit.The As content exceeds the national limit by 120 times.Pb exceeds The national limit is about 5times,while the Cu and Hg pollution is relatively light.2.The composition and changes of microbial flora on the surface of mussel meat during the frozen storage process were studied.The results showed that the effective sequence range of each mussel sample was 31934~42786,and the OTU range was 292~674.The fresh O mussel meat had the lowest OTU number,while the frozen OZ was 3 weeks and the frozen U.S.9 weeks sample had a relatively high OTU number.Fresh mussel meat is mainly dominated by Acinetobacter,Vibrio and a small number of Staphylococcus.At the genus level,the relative abundance of Acinetobacter and Shewanella in the mussels was significantly increased compared to fresh mussel meat and frozen mussel meat for 1 week.It may be related to mussel death and microbial contamination.In addition,with the increase of freezing time,the dominant microbes,microbial structure,abundance and mutual proportion of mussels showed significant changes.Therefore,it is necessary to adopt different control techniques for mussels of different freezing periods to ensure the quality and safety of mussels.3.The protective effect of composite glazing technology on the quality of frozen mussels was studied.Taking the traditional distilled water glaze treatment as the control,the effects of composite glazing on the quality indexes of frozen mussel meat were evaluated,and the application effect and practical application of the composite glazing technology were determined.The results showed that the treatment of pullulan + weakly acidic electrolyzed water,stable chlorine dioxide + weakly acidic electrolyzed water composite galvanized coating can significantly inhibit the increase of surface microbial and volatile base nitrogen content in frozen mussel meat,and Composite galvanized treatment has a positive effect on maintaining the texture characteristics of mussels,maintaining myofibrillar protein content and stabilizing total sulfhydryl content.The microstructure observation of the tissue revealed that the muscle tissue of the above two composite galvanized treatment groups was still tight compared with the blank control group,and the relative integrity of muscle protein was maintained.Therefore,the composite glazing technology can be selected as a technical means to maintain the quality of frozen mussel meat and prolong its shelf life.4.The quality assurance and microbial inhibition of mussels were studied.The changes of various quality indexes of mussels under different heating time(6 h,12 h and 18h)and heating temperature(45°C,55°C and 65°C)were measured,and the low temperature heat treatment technology was applied to mussel meat.Inhibition of microbial content.The results showed that different treatment temperatures and heating time had significant effects on the quality characteristics of mussels.After heating at 45°C,55°C and 65°C for 6h,mussel muscle elasticity,chewiness,color difference,total sulfhydryl content and pH were at a high level;Then,as the heating time increases,the above characteristic indexes gradually decrease,indicating that the quality characteristics of mussels continue to decrease as the heating time is prolonged.The mussel muscle cooking loss rate was the lowest when heated at 45°C for 6h,but other quality characteristics were significantly lower than the 55°C and 65°C treatment groups;In addition,heat treatment at 65°C,in the control of mussel muscle microbial content,elasticity,chewiness and malondialdehyde content,are significantly better than 55°C heating conditions.Therefore,in the shelf life and food quality allowable standards,it is recommended to use high temperature treatment conditions of 65°C heating for 6h to process mussels.