Quality Change Of Daohua Chicken Under Different Storage Temperature And Application Of Preservation Technology

Daohua chicken is an important raw material for making white cut chicken and other special dishes in South China.It is rich in nutrients and prone to soillage and deterioration.In this paper,the quality changes of Daohua chicken at different storage temperatures and the changes of bacterial diversity affecting spoilage and deterioration of Daohua chicken during storage were studied,and the shelf-life prediction model was constructed by using the dominant spoilage bacteria and the total number of bacteria.The dominant spoilage bacteria were used to screen the preservatives suitable for prolonging the shelf life of Daohua chicken,and finally the optimal compound ratio of three natural preservatives of chitosan,tea polyphenols,ε-polylysine was obtained by the response surface optimization method,and the preservation effect of the formula was studied.The main research results are as follows:1.The proportion of protein,fat,ash,moisture and total dry matter content of Daohua chicken was 22.43%,1.35%,1.12%,74.95%and 25.05%,respectively.The total number of colonies was 6.66 lg（CFU/g）and the TVB-N value was 15.62 mg/100g at 0.5 d of Daohua chicken stored at 25℃,which just exceeded the national standard limit.The sensory score was 12.10 and declined sharply thereafter;The moisture content was 73.68%,and then increased greatly.The p H value showed a significant upward trend.At 4℃,the total colony value of 4 days was 6.77 lg（CFU/g）,which exceeded the national standard limit.The TVB-N value of 13.21mg/100g on the 4th day and 23.66 mg/100g on the 6th day exceeded the prescribed limit.The sensory score was 8.40 points on the 4th day and decreased to 6.30 points on the 6th day.The moisture content reached 76.09%on the 4th day and 77.93%on the 6th day,which exceeded the prescribed limit,and the p H value increased significantly from 4 to 10 days.The total colony value at 0℃was 5.84 lg（CFU/g）on the 8th day,and 6.94 lg（CFU/g）on the 10th day,which exceeded the prescribed limit.The value of TVB-N was 16.25 mg/100g on the 8th day and 21.03 mg/100g on the 10th day,which exceeded the prescribed limit.The score of sensory assessment was 9.90 on the8th day,and decreased to 6.40 on the 10th day.The moisture content value was 76.34%on the 10th day,which was about to exceed the prescribed limit.The p H value increased significantly after the 8th day.In conclusion,the shelf life of Daohua chicken is 0.5 days at room temperature at 25℃,about 4 days at 4℃,and about 8 days at 0℃.2.High-throughput sequencing technology based on 16S r DNA gene was used to analyze the changes of bacterial diversity in the early,early and late spoilage of Daohua chicken under the conditions of 25℃room temperature storage,4℃cold storage and 0℃ice storage.Under different storage temperatures,there were significant differences in microbial community richness and succession.Altogether,22 phyla,36 classes,90 orders,148 families,291 genera were identified.The total number of bacteria OUT was 579.At the level of phyla,Proteobacteria,Firmicutes,Bacteroidetes and Actinobacteria were the dominant phyla.At the genus level,the dominant spoilage bacteria preserved at room temperature at 25℃were Acinetobacter bacteria,Serratia bacteria,Pseudomonas bacteria,Pantoea bacteria,unclassified Enterobacteriaceae bacteria,etc.The dominant spoilage bacteria were Pseudomonas,Acinetobacter,Serrella,unclassified Enterobacteriaceae and Marseillae bacteria,but there were significant differences in their abundance between storage at 4℃and 0℃.3.Under different storage temperatures,The dominant spoilage bacteria in the spoilage process of Daohua chicken were Pseudomonas and Serratia Enterobacteriaceae.The shelf life prediction model was established with total colony count as quality index,Ea=57967J/mol,K₀=7.87×10¹⁰,t=（ln A_t-ln A₀）/(7.87×10¹⁰×e^-57967/RT).The shelf life prediction model was established with Pseudomonas as the quality index,Ea=48634 J/mol,K₀=1.70×10⁹,t=（ln A_t-ln A₀）/(1.70×10⁹×e^-48634/RT).The shelf life model was established with Serratia Enterobacteriaceae as quality index,Ea=60922 J/mol,K₀=3.79×10¹¹,t=（ln A_t-ln A₀）/(3.79×10¹¹×e^-60922/RT).Three kinds of shelf life prediction models were verified,and all of them could make real prediction of their respective indicators,with the maximum relative error of 7%.Within the allowed range,the shelf life prediction model of Pseudomonas had the best prediction effect.4.The inhibitory effects of five preservatives on the dominant spoiling bacteria were compared,and the inhibitory effects of chitosan,tea polyphenol andε-polylysine on the dominant spoiling bacteria in Daohua chicken were more significant.The solution concentrations of each component of the compound preservatives were optimized aschitosan 0.25%,tea polyphenol 0.9%andε-polylysine 2.42%by response surface method.Under the same conditions,adding preservative could effectively extend the shelf life of chilled Daohua chicken to 14 days,and the total number of colonies and volatile saline-based nitrogen values were in line with the national standards,and the p H value,moisture content and sensory evaluation changed smoothly during the whole storage period,which all reached the edible standards.The application of natural preservative can maintain the good quality of chilled Daohua chicken and prolong its shelf life.In conclusion,The shelf life is 0.5 days under 25℃normal temperature storage condition,4 days under 4℃refrigerated preservation condition,and 8 days under 0℃ice-temperature storage condition.The shelf life of the product can be effectively extended to14 days by freezing temperature storage at 0℃and applying with natural preservative.