Cold Acclimation And Application Of Weissella With Color Protection In Meat

The effects of protecting color of two Weissella strains(W.cibaria X31 and W.confusa L2)at 30?,20?,15?,10?,4? were studied by acclimation of gradient cooling and adding compatible solutes;the 4D Lable-free quantitative proteomics was used to explore the adaptation mechanism of X31 for cold stress;the effects of X31 and L2 as color protector in low nitrite dry fermented sausages on the physicochemical properties,sarcoplasmic and myofibril proteolysis,and volatile compounds were examined.The results are as follows:(1)The acclimation of X31 and L2.Two strains grew stably at low temperature after acclimation of gradient cooling and adding compatible solutes.The results of gradient cooling demonstrated that the two strains showed best growth at 20?,and the life was 12 d at 4?.The 1g/L betaine,0.5g/L L-carnitine and 3g/L Tween-80 were optimized by response surface,which provide best protection for X31 and L2 grown at 4?.X31 and L2 showed significant color protection after cold acclimation.Furthermore,the effect of adding compatible solutes was better than gradient cooling on color protection of X31 and L2.(2)The proteomic analysis of X31.1,320 proteins were identified by proteomics.Among them,272 proteins were up-regulated and 171 proteins were down-regulated.The proteins annotation showed that transport and synthesis of carnitine and betaine,cold shock and stress proteins were up-regulated,which were main mechanism for X31 to response cold stress.Acetatolactate synthase,50 S ribosoma protein L9 and 30 S ribosoma protein S20 were up regulated to maintain the stable function of cell membrane and ribosoma.GO enrichment and COG functional analysis showed that proteins involved in cell functions such as sugar metabolism and synthesis,nucleotide metabolism,carbohydrate transport and metabolism,translation,ribosome structure and biosynthesis were differently expressed.The analysis of KEGG pathway showed that the up-regulation of the phosphotransferase system increased the glucose phosphorylation and transport,and increased the carbohydrate metabolism of X31.The up-regulation of pantothenic acid and Co A biosynthesis pathways indicated that Co A could cause stress response and promote cell homeostasis in X31.(3)The application of X31 and L2 in dry-fermented sausage.The addition of 8log cfu/g of X31 and L2 decreased the p H,water activity,and nitrite content of sausages.The redness,hardness,adhesiveness,and chewiness of sausage were increased during processing.X31 and L2 strains could also hydrolyze myofibrillar proteins in sausages.The sausage inoculated with L2 was more abundant in ester compared to the control.In summary,the analysis of the color protection and mechanism of cold stress presented in this study which would provide a theoretical basis to improve the tolerance of strains in cured meat at low temperature.