Study On The Spoilage Rule And Sterilization Technology Of Chilled Siniperca Chuatsi

Siniperca chuatsi is a precious freshwater economic fish.Its meat is extremely elastic,without any muscle thorns,and is rich in high-quality protein,so it is favored by consumers.It is loved by the majority of residents.However,due to its large amount of protein,soft meat and high moisture content,if proper preservation methods are not adopted,mandarin fish is prone to spoilage during low-temperature transportation and fish processing,resulting in significant economic losses.The spoilage process of mandarin fish is greatly impacted by microbial elements.This paper explored the types of spoilage bacteria and their capacity to cause the deterioration of the quality of cold fresh mandarin fish at the end of storage,as well as the main spoilage bacteria,and the spoilage mechanism of cold fresh mandarin fish was revealed.Secondly,the quality changes of cold fresh mandarin fish at different storage temperatures were studied,and the best storage temperature suitable for mandarin fish was selected.The initial number of colonies before storage is very important to the shelf life of aquatic products.Therefore,the reduction of bacteria is one of the effective ways to improve its preservation in the later period.Therefore,this paper finally studied the effects of acidic electrolyzed oxidizing water,sodium hypochlorite water and chlorine dioxide water on the freshness change of mandarin fish during storage,and compared them to screen out the best method for reducing bacteria suitable for mandarin fish,which provides an important basis for the cold storage of mandarin fish.The main results are as follows :The samples of chilled mandarin fish were taken on the 0 d,5 d and 7 d of storage,and the microbial system classification and species composition in the spoilage samples of chilled mandarin fish were studied by high-throughput sequencing with amplified sequence variants as molecular markers.The microbial diversity in the process of corruption was analyzed and compared.The dominant spoilage bacteria of chilled mandarin fish were mainly Proteobacteria,Aeromonas and Shewanella.A total of 44 colonies with good growth and typical morphology were selected by dilution coating plate and plate streaking separation method.After screening,we finally identified 44 strains with good growth and distinctive appearance characteristics by dilution coating plate and plate streaking separation method.The 44 strains were identified by 16 S rRNA gene identification technology,and 7 kinds of spoilage bacteria were obtained by removing repeated strains.They were Aeromonas salmonicida,Aeromonas bestiarum,Aeromonasencheleia,Streptococcus parauberis,Shewanella putrefaciens,Shewanella hafniensis and Aeromonas veronii.Among them,Aeromonas thermophila has the strongest corruption ability.In order to investigate the cleaning and sterilization effects of acidic electrolyzed oxidizing water,sodium hypochlorite water(40-49 mg / L)and chlorine dioxide water(10 %)on the surface of Siniperca chuatsi,the sterilization effects of these three preservatives with different soaking time on Siniperca chuatsi were compared.In the acidic electrolyzed oxidizing water,the best soaking time was 30 min.On the 9 th day,the TVB-N value reached the minimum of 26.36 mg / 100 g,and the total number of bacteria was 8.87lg(cfu / g).In sodium hypochlorite water,the best soaking time was 20 min.On the 9 th day,the TVB-N value reached the minimum of 25.50 mg / 100 g,and the total number of bacteria was 7.26 lg(cfu / g).In chlorine dioxide water,the best soaking time was 15 min.On the 9th day,the TVB-N value reached a minimum of 21.09 mg / 100 g,and the total number of bacteria was 6.42 lg(cfu / g).By comparison,the effects of the three bacteria reducing agents were significantly better than sterile water(p < 0.05),and the best treatment for bacteria reduction was chlorine dioxide soaking for 15 min,which could achieve good antibacterial effect.In order to investigate the cleaning and sterilization effects of acidic electrolyzed oxidizing water,sodium hypochlorite water(40-49 mg / L)and chlorine dioxide water(10 %)on the surface of Siniperca chuatsi,the sterilization effects of these three preservatives with different soaking time on Siniperca chuatsi were compared.In the active electrolyzed oxidizing water,the best soaking time was 30 min.On the 9th day,the TVB-N value reached the minimum of 26.36 mg / 100 g,and the total number of bacteria was 8.87lg(cfu/g).In sodium hypochlorite water,the best soaking time was 20 min.On the 9th day,the TVB-N value reached the minimum of 25.50 mg / 100 g,and the total number of bacteria was 7.26 lg(cfu / g).In chlorine dioxide water,the soaking time of 15 min was the best.On the 9th day,the TVB-N value reached a minimum of 21.09 mg / 100 g,and the total number of bacteria was 6.42 lg(cfu/g).By comparison,the effects of the three preservatives were significantly better than sterile water(p<0.05),and the best treatment was chlorine dioxide soaking for 15 min to achieve good antibacterial effect.In summary,mandarin fish is rich in a variety of nutrients,but it is highly perishable;the preservation method of soaking in chlorine dioxide for 15 min at 4 °C can prolong the shelf life of mandarin fish and has a good preservation effect.After in-depth research,Aeromonas bestiarum has been proved to be the most common spoilage bacteria in the storage process of mandarin fish.Therefore,the results of this study can be used as an important basis for the preservation of mandarin fish to ensure its good preservation performance.