Prediction Of Shelf Life Model And Analysis Of Bacterial Diversity Of Fermented Scomberomorus Niphonius

Scomberomorus niphonius is a kind of high-quality raw material for fish processing because of its rich nutrition,fine quality and delicious taste.Lactococcus lactis was used as the fermentation agent to make Scomberomorus niphonius.The orthogonal test was used to optimize the fermentation conditions and the seasoning formula.The changes of sensory quality,total plate count,TBA,pH,color,juice loss rate,and other indexes of fermented Scomberomorus niphonius products under different storage temperatures?4,15,25??were studied.The Pearson correlation coefficient among the indexes was analyzed,with the key factors were selected to establish the shelf-life prediction model.Furthermore,the high-throughput sequencing technology was used to analyze the bacterial species diversity of fermented Scomberomorus niphonius during storage.The main research contents are as follows:1.The optimal fermentation conditions of Scomberomorus niphonius were selected as follow:the inoculation amount of the fermentation agent was 4%,the fermentation time was 12 h,and the fermentation temperature was 37?.The order of the influence of the amount of raw materials in the seasoning formula on the quality of fermented Scomberomorus niphonius is as follows:salt>chili powder>pepper powder>ginger powder.The optimal formula combination is as follows:salt addition amount was 3%,chili powder addition amount was 3%,pepper powder addition amount was 1.5%and ginger powder addition amount was 1.5%.The prepared product under this fermentation condations had compact meat,attractive golden color,rich fragrance,elasticity,good chewability and delicious taste.2.The total plate count,TBA value and juice loss rate of fermented Scomberomorus niphonius products increased with the extension of storage time,while the values of L^*,a^*,b^*and sensory score decreased under different storage temperature?4,15,25??,and the higher the storage temperature,the more obvious the change trend.The Pearson correlation coefficient analysis results showed that the Pearson correlation coefficient of other indicators was greater than 0.92 except pH value and b^*,among which the linear correlation of the total plate counts is the highest,indacating it can be used as a key factor for shelf-life prediction.3.The total plate count was selected as the key factor to predict the shelf-life model,and regression analysis was made on the exponential equation of the total plate count of fermented Scomberomorus niphonius with storage time under different storage temperatures.The activation energy E_a of the total number of colonies was 5.81×10⁴J/mol,and the pre factor K₀ was 1.47×10¹¹.According to the model,the theoretical shelf-life of Scomberomorus niphonius at 2,10 and 20?was 46,22 and 14 days respectively,which was consistent with the measured value of the shelf,and the relative error was about 10%,indicating the Arrhenius equation had a high fitting degree.This model can be used to predict the theoretical value of the shelf life of the fermented Scomberomorus niphonius at different storage temperatures,and provide some reference for the prediction of the shelf life model of the prefabricated conditioning aquatic products.4.A total of 217 OTU were found by OTU taxonomy analysis,indicating that the rich bacterial community structure of fermented Scomberomorus niphonius.The results of the analysis of Alpha diversity and species distribution showed that the richness and diversity of bacterial community were higher in the middle stage of storage.Among them,at the level of phylum and class,the proportion of Gammaproteobacteria in Proteus was the highest,accounting for more than 90%.At the level of order and family,Vibrionales and Vibrionaceae were the most dominant flora,accounting for more than 50%.At the genus level,Photobacterium,Vibrio and Shewanella were the main genera.Therefore,in the storage process of fermented Scomberomorus niphonius,the production conditions should be strictly controlled to avoid the breeding of dominant spoilage bacteria.