Proteomics-based Analysis Of The Effect Of Sodium Lactate On The Quality Of Cold Beef

With the increase in beef production and consumption in China,producers and consumers are increasingly concerned about the quality of beef.Chilled beef is nutritious and tasty,but problems such as short shelf life and perishability are more serious,so choosing a suitable means to preserve chilled beef is a problem that needs to be solved in the current beef industry.Sodium lactate,as a natural non-toxic food preservation agent,is currently mostly used in smoked and processed meat products to prevent spoilage,but rarely used in fresh meat to maintain freshness.Therefore,in this paper,we used fresh beef as the research object and analyzed sodium lactate preservation technology using non-labeled quantitative proteomics（Label-free）to reveal the changes of quality and protein synthesis and expression of sodium lactate-treated beef during storage at 4℃;elucidated the effects of sodium lactate treatment on intercellular cell enzyme activity and glycolytic pathway of beef;and comprehensively analyzed the effects of sodium lactate on the quality of cold fresh beef and The mechanism of color protection of cold beef was analyzed.The specific conclusions are as follows:1.Using chilled beef as the research object,the 3%sodium lactate treated and control beef groups were placed in a refrigerator at 4℃and refrigerated for 1,2,3,4,5,6 and 7 d.The samples were sampled at 1,2,3,4,5,6 and 7 d.The p H,color saturation,juice loss rate,TVB-N value,TBARS value,total microbial content and relative myoglobin content were analyzed in a comprehensive comparison.The results showed that the sodium lactate treated group was superior to the control group in terms of physicochemical and color saturation,especially in terms of color and relative content of myoglobin showed significant advantages.Compared with the control group,the beef treated with sodium lactate consistently maintained a higher a*value,indicating good meat color.While the content of oxy-myoglobin（Oxy Mb）of beef in the control group showed a linear decrease to about 25%,the Oxy Mb content of the sodium lactate treated group was consistently maintained at about 65%.This indicates that sodium lactate treatment can effectively reduce the oxidation rate of beef,prevent the quality deterioration of beef,and keep the beef in a better color and morphology.2,The proteomic characteristics of beef in the sodium lactate-treated and control groups during storage were investigated by applying a non-labeling quantitative proteomics（Label-free）method,and the measured protein molecular weight distribution and protein discrimination coverage were good,indicating that the protein data were credible and worthy of further study.The analysis of differential proteins revealed that the number of down-regulated differential proteins was significantly higher than the number of up-regulated differential proteins in the sodium lactate treated and control groups during 1,3 and 5 d storage,indicating that the increased protein activity in beef after 5 d was involved in more biochemical reaction processes.These differential proteins mainly consisted of antioxidant proteins,chaperone proteins,enzymes related to glycolytic processes and enzymes related to energy metabolism,etc.These proteins are involved in biochemical processes that alter the organism’s environment,so they may be potential markers of color changes in beef quality.The results of subcellular structural localization showed that the protein localization of both groups of samples was mainly in the cytoplasm,nucleus and mitochondria,which indicated that the quality stability of beef was related to the cytoplasm,nucleus and mitochondria.The GO enrichment analysis of beef showed that the main biological processes involved in the differential proteins were biological process regulation and cellular process regulation.The results showed that the color stability of fresh beef treated with sodium lactate was highly correlated with the above biochemical reactions,so the brighter red color could still be maintained after 5 d of storage.3.A comprehensive analysis of the glycolysis rate and the changes of intercellular enzyme activities of beef longest muscle under refrigeration conditions after sodium lactate treatment showed that the muscle glycogen content of the sodium lactate treated group was lower than that of the control group,and the lactic acid content was higher than that of the control group,while the enzyme activities of HK,LDH and MRA in the treated group were higher than those of the control group.The comprehensive analysis of beef color indexes showed that sodium lactate could slow down the accumulation of lactic acid to keep the p H value of beef stable and improve the color and quality of beef.From the viewpoint of glycolysis rate,sodium lactate promoted the increase of glycolysis rate and increased the content of NADH,which played a crucial role in the initiation of Fe³⁺-Met Mb reduction reaction.