Study On The Eating Safety Of Cooked Crayfish (Procambarus Clarkii) And Its Process Control

Crayfish is favored by consumers because of its nutritional richness and unique flavor.In the post-COVID-19 era,pre-prepared crayfish products had mushroomed.However,the uneven quality of products has led to frequent food safety incidents,limiting the long-term development of the cooked crayfish industry.The reasons for the deterioration of the eating safety quality of cooked crayfish are still unclear,and there is a lack of systematic research on the changes in eating safety risks during the processing and storage of cooked crayfish.Therefore,this paper took cooked crayfish as the research object,combined with the changes in physical and chemical indexes and high-throughput sequencing technology,analyzed the changes in eating safety and quality of commercially available cooked crayfish during storage,and identified the key influencing factors.At the same time,based on the actual situation of product sales and consumer behavior,the changes in physical and chemical indexes of commercial crayfish in thawing treatment and temperature fluctuation were analyzed,and the eating safety and quality problems of commercial crayfish exposed to consumer behavior were clarified.Finally,on the basis of the above,combined with the microbial changes of key processing points during the processing of cooked crayfish,the optimal technology was obtained by optimizing the frying parameters,and stability verification was carried out to obtain high-quality crayfish products.This study provides data and theoretical support for the crayfish processing industry and has important significance for the development of safe and high-quality cooked crayfish within a certain shelf life.Firstly,the physical and chemical indexes and microbial changes of different parts of refrigerated and frozen commercial cooked crayfish during storage were investigated,and the key factors affecting the eating safety of cooked crayfish during storage were determined.The results showed that: in terms of freshness index,the total volatile base nitrogen(TVB-N)in refrigerated cooked crayfish meat,viscera and gills was 32.83mg/100 g and 37.58 mg/100 g,respectively,exceeded the upper limit of the national food safety standard,after 35 days of storage,while the total number of colonies reached 7.50 lg CFU/g and 7.64 lg CFU/g.TVB-N values of meat.Viscera and gills in frozen cooked crayfish gradually increased during storage and exceeded the limit value at 180 days,reaching 32.42 mg/100 g and 31.26 mg/100 g.In terms of fat oxidation,the presence of sauce in cooked crayfish products makes them more susceptible to lipid oxidation.In refrigerated crayfish,The peroxide value(POV)of the sauce in refrigerated cooked crayfish first increased to 0.38 g/100 g and then decreased to 0.21 g/100 g,and the thiobarbituric acid value(TBA)gradually increased to 1.15 mg MDA/kg,and the oxidation degree gradually deepened.The POV value of frozen cooked crayfish sauce gradually increased from 0.16g/100 g to 0.55 g /100 g.In terms of bacterial facies composition,the main dominant bacteria in the late storage stage of refrigerated cooked crayfish were Carnobacterium,Serratia,and Brochothrix.The dominant bacterial genera in frozen cooked crayfish at the end of storage were Psychrobacter,Lactobacillus,Vibrio,and Acinetobacter.Secondly,in order to solve the problem of whether improper consumption behavior will increase the eating safety risk of cooked crayfish,different thawing methods and refrigeration temperature fluctuations were used to simulate the potential improper consumption behavior of frozen and refrigerated cooked crayfish,and the key factors affecting the eating safety of cooked crayfish in the consumption process were clarified.The results showed that different thawing methods could affect the eating safety of frozen cooked crayfish.Thawing at room temperature could easily expose more eating safety quality problems of crayfish,and the microbial population increased by 0.51 lg CFU/g～0.92 lg CFU/g,which accelerated the deterioration of cooked crayfish.The number of cold-ophilic bacteria increased by 0.26 lg CFU/g～0.51 lg CFU/g under the condition of low-temperature thawing,which resulted in certain eating safety risks.Thawing with heating and microwave can inhibit the number of microorganisms,but accelerate the degree of lipid oxidation.The POV value of the sauce increased by 0.13 g/100 g and 0.11 g/100 g,respectively.The thawing rate of water thawing was fast,and there was no significant difference between the indexes and the control group,which could maintain the original quality better.The fluctuation of refrigeration temperature between 4°C and 10°C will affect the eating safety of refrigerated cooked crayfish.During the cycle,the values of TVB-N,POV,and TBA showed an increasing trend.At the end of 7 cycles,the TVB-N value of cooked crayfish meat changed the most,reaching 24.76 mg/100 g.The total number of colonies in the viscera and gills was the highest,reaching 3.45 lg CFU/g.The fat in the sauce was most easily oxidized during the temperature fluctuation,and the TBA value reached 0.81 mg MDA/kg at the end of the cycle.At the beginning of the temperature cycle,the main bacteria genera in cooked crayfish were Psychrobacter,Subdoligranulum,Bacteroides,and Faecalibacterium.During the cycle,the relative contents of Subdoligranulum,Bacteroides,and Faecalibacterium gradually lost their dominance,while Vibrio and Psychrobacter gradually occupied the dominant position.The results showed that in the cycle of temperature fluctuation,the microorganisms were easy to grow rapidly and produce dominant strains,thus increasing the risk of eating safety.Finally,according to the previous research on the safety of cooked crayfish during the storage process and consumer behavior,it was concluded that refrigerated cooked crayfish was more susceptible to microbial influence and produced eating safety risk,and the key processing technology was studied and optimized,and the influence of key processing technology on eating safety quality and storage safety of refrigerated cooked crayfish was clarified.The results showed that there were differences in microbial diversity during processing.The number of microbes in raw crayfish was higher,with the total number of colonies being 7.50 lg CFU/g～8.40 lg CFU/g,and the relative content of Psychrobacter was13.89%.In the cleaning process,the total number of colonies decreased by 2.11 lg CFU/g～2.92 lg CFU/g,but some Vibrio and Aeromonas remained.Frying further reduced the total number of colonies by 3.21 lg CFU/g～3.28 lg CFU/g,but a small amount of Bacteroides and Subdoligranulum remained.After cooking,the relative content of each microorganism was less than 5.00%.Carnobacterium and Serratia were not detected after processing.The relative content of Brochothrix was less than 0.02% after frying and boiling.The results of the principal component analysis showed that the microbial community structure was relatively similar after frying,cooking,and packaging,and the number and species of subsequent microorganisms could be further reduced by frying.The optimal frying temperature and time were 210°C and 100 s,under which the microorganisms could be effectively inhibited,the TBA value was 0.36 mg MDA/kg,and the degree of lipid oxidation was low.Under the optimal frying conditions,the shelf life of refrigerated cooked crayfish could be effectively extended,and the TVB-N value at 35 d was 26.50 mg/100 g,and the total number of colonies was 4.27 lg CFU/g,both of which were lower than that of commercially refrigerated cooked crayfish in the same period.In addition,after 7temperature cycles,the eating safety quality of the product was higher than that of the commercially available products.