Study On Flavor Formation And Protein And Lipid Metabolism During Traditional Processing Of Zhenba Bacon

Chinese bacon is a traditional dry-cured meat product with a long history as an essential part of Chinese traditional food culture.It has made outstanding achievements in poverty alleviation and rural revitalization as a geographical landmark product in China.The flavor of Chinese bacon is an important index of the quality of pork products and the acceptability of consumers.The flavor of Chinese bacon is closely related to the changes in protein and lipids.In this paper,the flavor formation of Zhenba bacon was analyzed by measuring the flavor and physicochemical index in different stages of the traditional processing method.Lipidomics and proteomics were used to analyze the lipid and protein metabolism of Zhenba bacon during processing and provided theoretical guidance for the flavor formation of Chinese bacon by ultrasonic-assisted curing.The main results are shown as follows.(1)The differences in traditional Chinese bacon in different regions are analyzed on aroma(including Sichuan,Hunan,Guangzhou and Zhenba),and the experimental results are as follows.There are great differences in the flavor substances of Chinese bacon in different regions,which can be effectively distinguished according to the flavor characteristics.Zhenba bacon responded strongly to alcohol,some aromatic compounds,and methyl groups in W2 S and W1 S probes.Among the highest content of the five substances of flavor are hexanal,guaiacol,phenol,ethanol,and 4-methyl guaiacol.GC-IMS analysis showed that the characteristic flavor substances of Zhenba bacon were 3-methyl-butanol and 2-methyl-1-propyl alcohol.(2)Flavor analysis of Zhenba bacon at different processing stages(including YL stage,YZ stage,XZ stage and CP stage).The experimental results are as follows: The flavor substances of Zhenba bacon at four processing stages were analyzed by GC-MS,and GCIMS combined analysis.The curing periods are the key periods for the flavor formation of Zhenba bacon.During the curing period,a large number of ester substances began to be produced,mainly isoamyl acetate,ethyl caproate,and ethyl lactate.In the smoking period,the flavor substances are mainly phenolic,including 2-methyl phenol,3-methyl phenol,4-methyl guaiacol,4-ethyl guaiacol,guaiacol,and phenol.(3)Determination of physicochemical indexes of Zhenba bacon at different processing stages,according to hydrolytic oxidation around lipids and proteins,as follow:The hydrolysis and oxidation of protein and lipid were analyzed.In lipids,POV and TBARS increased first and then stabilized during the processing stages.The content of the ATGL enzyme was the highest in the YZ stage,while the HSL enzyme was the opposite.At the same time,the content of FFA decreased significantly during the curing period.In the protein,the carbonyl value showed a trend of slow rise at first and then declined,and the sulfhydryl value was the highest in the curing stage.The contents of Asp,Glu,His,and Pro decreased sharply during curing and fumigation,which can promote the formation of flavor.(4)The molecular level of Zhenba bacon at different processing stages was analyzed by proteomics and lipidomics.Label-free proteomics was used to analyze Zhenba bacon at different processing stages.It was found that the curing process changed 42 kinds of proteins,including 14 up-regulated proteins and 28 down-regulated proteins.The smoking process altered the expression of 45 proteins,including 25 up-regulated proteins and 20down-regulated proteins.The classification of lipids in Chinese bacon was analyzed utilizing lipidomics.The main lipids were triradylglycerols,phosphatidylcholine,diradylglycerols,phosphatidylethanolamine,phosphatidylserine,medium-chain phosphatidylcholine,mono galactosyl diglycerol,and phosphatidylinositol.The proportions were 47.7%,15.8%,7.7%,6.8%,and 5.1%.The lipids PE,PC,TG,DG,and Bis Me PA are active in the curing stage.It was found that phospholipids play a dominant role in the processing of Chinese bacon,which is vital for the formation of flavor.(5)The effect of different power ultrasonic curing on the flavor of bacon.The experimental results are shown as follows: Three ultrasonic waves(U200,U400,and U600)of different powers were used to promote the curing process of Chinese bacon.In the ultrasonic treatment group,the contents of PC and PE in phospholipids were higher.In addition,phospholipase activity plays a leading role in the curing stage of bacon.Ultrasonic treatment changed the hardness of the bacon in the curing stage.The hardness of bacon reached the maximum under the U200 treatment.Ultrasonic treatment promoted the formation of ethanol into other flavor compounds.PLSR analysis showed a correlation between enzyme activity and U600,indicating that high-power ultrasonic treatment dramatically affects the lipase activity of Chinese bacon.The most volatile compounds near U600 are mainly methyl butyrate,ethyl butyrate,ethyl acetate,and methyl valerate.