| Grilled lamb skewers with tamarix sticks are made by tamarix sticks string and charcoal fire.It is a traditional meat product of our country,and its unique color,aroma and taste are deeply loved by consumers.However,at present,the grilled lamb skewers with tamarix sticks processing industry is facing the problems of unstable quality,unclear characteristic quality and difficult to maintain quality.Analyzing the characteristic quality and flavor formation regulation of grilled lamb skewers with tamarix sticks is the key to maintain the characteristic quality of grilled lamb skewers with tamarix sticks.Therefore,the grilled lamb skewers with tamarix sticks were taken as the research object in this study to explore quality change of grilled lamb skewers with tamarix sticks and changing regulation of characteristic flavor compounds,flavor precursor,moisture content and morphology,in order to lay a theoretical foundation for maintaining the characteristic quality of grilled lamb skewers with tamarix sticks.The specific results are as follows:(1)Taking grilled lamb skewers with iron sticks as control,texture,color,flavor and senses as key indexes,the quality change regulation of grilled lamb skewers with tamarix sticks was made clear.The results showed that the hardness of grilled lamb skewers with tamarix sticks was about 19%lower than that of grilled lamb skewers with iron sticks,and the chewiness is about 12%lower.The L*value and b*value of grilled lamb skewers with tamarix and iron sticks increased significantly with the extension of grilling time,while the a*value was on the contrary.In the traditional grilling process,54 and 44 volatile flavor compounds were identified respectively,in which aldehydes and alcohols were rich and high in content,which were the main volatile flavor compounds in grilled lamb skewers with tamarix sticks.In the grilling process,there were 18 key flavor compounds of grilled lamb skewers with tamarix sticks with OAV>1.1-octene-3-ol,(E,E)-2,4-decadienal,hexanal,(E)-2-nonenal,(E,E)-2,4-nonadienal,nonanal,(E)2-decenal and heptanal were characteristic flavor compounds.A total of 9 key flavor compounds of grilled lamb skewers with iron sticks with OAV>1 were identified.Among them(E)-2-nonenal,(E,E)-2,4-decadienal and 1-octene-3-ol were characteristic flavor compounds.The sensory score of lamb skewers with tamarix sticks was significantly(P<0.05)higher than that of lamb skewers with iron sticks in terms of flavor,tenderness and overall liking.Flavor was the key factor affecting sensory score and consumer acceptability of grilled lamb skewers with tamarisk sticks.(2)Taking the quality characteristics as X variable and processing time as Y variable,the key compounds for the quality formation of grilled lamb skewers with tamarix sticks were confirmed by partial least square discriminant analysis(PLS-DA)and variable projection importance analysis(VIP).The results showed that there were 22 key compounds(VIP>1)that played an important role in the quality formation of grilled lamb skewers with tamarix sticks in the charcoal grilling process.These included 1 electronic nose(W1W),3 basic ingredients(protein,moisture,fat),1 color(b*value),4 texture properties(hardness,springness,gumminess,chewiness),13 flavor compounds(2-pentyl-furan,heptanal,(E,E)-2,4-nonadienal,(E)-2-nonenal,(E)-2-octenal,nonanal,(E,E)-2,4-decadienal,1-octene-3-ol,(E)-2-octene-1-ol,naphthalene,tetradecanal,1-hexanol.anethole).A total of 17 key compounds(VIP>1)that played an important role in the quality formation of grilled lamb skewers with iron sticks in the traditional charcoal roasting process.Aldehydes and alcohols are the main flavor compounds that lead to the difference of final product quality between grilled lamb skewers with tamarix and iron sticks.Among the 16 components with VIP values greater than 1,12 were more representative of the quality of grilled lamb skewers with tamarix sticks,mainly aldehydes and alcohols,which included 2-pentyl-furan(1.132),(E,E)-2,4-decadienal(1.131),tetradecanal(1.130),(E,E)-2,4-nonadienal(1.129),(E)-2-nonenal(1.131),heptanal(1.127),(E)-2-octenal(1.123),nonanal(1.083),(E)-2-octene-1-ol(1.048),1-octene-3-ol(1.032),anethole(1.070),naphthalene(1.032).(3)The inner layer,middle layer and outer layer of grilled lamb skewers with tamarix sticks in the grilling process of 0,2,4,6 and 8 min were analyzed by HS-SPME/GC-MS to clarify the formation regulation of flavor compounds of grilled lamb skewers with tamarix sticks.The results showed that 32,39 and 43 kinds of volatile flavor compounds were identified in the inner layer,middle layer and outer layer,respectively,including aldehydes,alcohols,ketones,acids,esters,alkanes and other compounds.The contents of aldehydes and alcohols in the middle layer of the grilled lamb skewers with tamarix sticks were higher than those in the outer layer,and the contents of ketones,acids and alkanes in the outer layer were higher than those in the middle and inner layer.Specifically,13,15 and 15 kinds of key compounds with OAV>1 were identified in the inner layer,middle layer and outer layer of grilled lamb skewers with tamarix sticks,respectively.Hexanal,heptanal,octanal,nonanal,1-octene-3-ol,(E)-2-nonenal and(E,E)-2,4-decadienal were common characteristic flavor compounds in the inner,middle and outer layers of grilled lamb skewers with tamarix sticks.The contents of these characteristic flavor compounds were in the following order:middle layer>inner layer>outer layer.(4)By analyzing the changes of flavor precursors such as lipid,free fatty acids and moisture content and morphology in the inner,middle and outer layers of grilled lamb skewers with tamarix sticks during the roasting process of 0,2,4,6,8 min,the flavor precursors and the formation regulation of grilled lamb skewers with tamarix sticks were clarified.The results showed that the moisture content in the outer layer,middle layer and inner layer decreased significantly during the grilling process,and the moisture content in the outer layer,middle layer and inner layer was 61.73%,64.07%and 64.57%respectively during 8 min,and the fat content increased gradually,and the fat content in the inner layer,middle layer and outer layer were 4.07%,3.73%and 3.37%,respectively.The protein content increased gradually,contrary to the fat change,the protein content of the outer layer was the highest,the middle layer was the second,and the inner layer was the lowest.During 8min,the protein content of the outer layer,middle layer and inner layer was 32.87%,30.60%and 29.50%,respectively.The water in the grilled lamb skewers with tamarix sticks mainly exists in the form of immobilized water,the content of immobilized water decreased,the content of free water increased,and immobilized water transferred to free water.The outer layer has smaller pores and denser texture than the muscle fibers in the inner and middle layers.Seven kinds of free fatty acids were detected in the inner,middle and outer layer of grilled lamb skewers with tamarix sticks,including 3 kinds of saturated fatty acid(SFA),2 kinds of monounsaturated fatty acid(MUFA)and 2 kinds of polyunsaturated fatty acid(PUFA).Palmitic acid(C16:0),stearic acid(C18:0),oleic acid(C18:1)and linoleic acid(C14:0)are the main free fatty acids in grilled lamb skewers with tamarix sticks during grilling.The content of free fatty acids was inner layer>middle layer>outer layer,and the content of free fatty acids increased at first and then decreased during grilling. |
