| Jiang-lu meat is a type of very popular traditional Chinese meat products which are made by slowly cooking with brine containing various spices and soy sauce.Traditionally,the brines for making Jiang-lu meat are used repeatly,leading to the accumulation of soluble substances(such as free nucleotides and amino acids)in reused brines and contributing to the rich flavor of final products.However,the traditional ways for making Jiang-lu meat products likely result in products with inconsistent flavor,have low production efficiency and could not realize large-scale continuous production.With the development of modern society and improvement of living standards,consumers have an increase in demands for healthier Jiang-lu meat products and greener processing technology for making these products.Understanding the quality changes of reused brines during Jiang-lu meat processing is significant importance to ensure products with stable quality and to develop greener processing methods.There are some publications on the changes in nutritional,flavor and simple physical properties of repeatly used brines,but there is a lack of study on the flavor changes in reused brines.In this study,sensory evaluation(n=18),electronic nose and solid phase microextraction(fiber for PDMS/DVB/CAR)combined with gas chromatography-mass spectrometry(GC-MS)were employed to study the changes in volatile profile and flavor of resused brines added with one of three commonly used spices(including star anise,bay leaves and cardamom)or a mixture of 9 spices for producing Jiang-lu pork.This study would provide some theoretical bases to help monitor and compensate for the loss of volatile flavor compounds in repeatly used brines,improve the flavor quality of reused brines and produce Jiang-lu pork with stable quality.The study included three parts as follows:(1)Brines containing star anise were reused 1-7 times to make Jiang-lu pork(heated at 100 ℃ for 1 h).The volatile profile and flavor of brines after 1-7 times of repeated used were evaluated with triangle test for sensory evaluation(n=18),electronic nose and GC-MS.The brines used for one time and three times could be differentiated with sensory evaluation.Based on the overall odor characteristics of brines from the electronic nose analysis,all brines reused for different times could be distinguished except for that used for one and two times.Among a total of 37 volatile compounds identified,those derived from star anise mainly included anethole,eucalyptol,linalool,terpinen-4-ol,α-terpineol,cedar,fenchone,anisaldehyde and estragole.In addiont,the relative amounts of volatile compounds in brines decreased as the times for reusing brines increased and it is necessary to compensate for the loss of volatile compounds in repeatly used brines.Overall,the levels of volatile compounds in a brine decreased after it being repeatly used for three times.Therefore,about 40-50% of the initial amount of star anise is recommended to be added into the brine after it being used twice.A total of 69 volatile compounds were detected in the meat products cooked with star anise and the main volatile compounds and contents were relatively stable.The anethole and eucalyptus,characteristic compounds in star anise,always occupied a high proportion and has an important influence on the odor of the meat products.In addition,the volatile components of the other two control groups were analyzed.A total of 26 volatile compounds were detected in the meat brines without star anise and pork characteristic flavor compounds such as 2-pentylfuran,(E)-2-octenal,and(E)-2-nonenal were not detected.A total of 34 volatile compounds were detected in the brines only containing star anise.The total amount of volatile compounds decreased by about 63% after reused twice,and only 17% of first contents after resued four times.Anethole has the highest content(about 73% of the total content)after reused first time,and the content is reduced by about 65% after reused twice.(2)Bay leaves and cardamon were added into brines,separately,and the brines were reused 1-5 times to make Jiang-lu pork(heated at 100 ℃ for 1 h).For the brines with bay leaves,the results from the electronic nose analyses indicated that brines reused 2,3,and 4 times have similar odor profiles,which were different from the brine only used once.A total of 45 volatile compounds in the brines with bay leaves were identified based on GC-MS analysis.The levels of volatile compounds in brines decreased obviously as the times for reusing brines increased,especially for the alcohols,ethers,phenols and esters from bay leaves which decreased76%,74%,67%,54% after the brine was repeatly used twice.About 60% of the initial amount of bay leaves is proposed to be add into the brine after one time of cooking.For the brines with cardamon,brines repeatly used three and four times had similar overall odor characteristics,but different from those used for one and two times based on the electronic nose analyses,which were consistent with the results from sensory evaluation.There were 31 volatile compounds identified.The highest content of characteristic flavor components of cardamom was eucalyptol,followed by Terpinen-4-ol,Terpineol and linalool.The characteristic components of pork,(E)-2-heptenal,E-2-octenal,and 1-octene-3-ol were only detected in brines repeatly used for three and more times.The amounts of total volatile compounds and alcohols decreased first and then increased with the times for reusing brines increased,while brines reused three or four times had the minimum amount of total volatile compounds.Eucalyptus and terpineol were the major compounds contributed to these changes.(3)A mixture of nine commonly use spices based on a preselected recipewas used for making Jiang-lu pork.The brines with nine spices were repeatly used for 1-5 time.Based on electronic nose analyses,all brines reused for different times could be distinguished,while sensory evaluation could only lead to partillay differentiation of reused brines.A total of 52 compounds in brines were detected,including 17 aldehydes,4 alcohols,6 ketones,8 esters,9 hydrocarbons,5 phenols,and 3 ethers.The predominant compounds were(E)-cinnamaldehyde,anisaldehyde,anethole,4-terpineol,α-terpineol and fenchone.The amounts of total volatile compounds in brines decreased obviously as the times for reusing brines increased.The amounts of total volatile compounds in brine decreased 50% and 79%,respectively,after being reused twice and three times as compared to the brine after one time of cooking.The content of aldehydes was the highest in the brine being used once,accounting for 50% of the total volatile compounds,which decreased by 78% and 88%,respectively,in the brined reused twice and three times.In addition,the amounts of ethers,phenols,esters and hydrocarbons in brines showed a trend of decrease first and then increase as the times for reusing brines increased. |
PDF Full Text Request