Study On The Quality Of Dry Aged Lamb And Its Processing Suitability

With the development of economy,the consumption level and ability of people has been improved,and the demand for high quality lamb has been increasing gradually.At present,high quality lamb accounts for less than 5% of the total lamb consumption of market in China,but the demand of consumer is strong.Therefore,the research and production of high-quality lamb is accord with the needs of the industry.Dry aging is an aging method that putting raw meat(quarter or primal cuts)in a low temperature to produce pleasant flavor and texture.At present,the change of flavor precursors during dry aging process and the characteristics and suitability of cooking using dry aged lamb are still unclear.It is urgent to have systematic research on them.Therefore,this study used lamb gigots as the experimental material,study the effects on dry aging on meat quality,and to identify the appropriate cooking methods of dry aging lamb,to provide technical support for the development of high-quality meat.(1)The effect of dry aging on lamb quality and water distribution were studied.The lamb gigots were randomly into wet aging,dry aging at 80% relative humidity(RH80 dry aging),dry aging at 60%relative humidity(RH60 dry aging).And the samples at aging 0 d,7 d,14 d,21 d and 28 d were selected.The p H,shear force,color,water holding capacity(WHC),water distribution and protein secondary structure of lamb were measured.The results showed that,the tenderness and WHC of lamb could be improved by dry aging.The different relative humidity had a significant effect on color,drying loss and cooking loss of dry aged lamb during 28 d of aging.For three aging groups,immobilized water had the largest proportion among the total water in lamb.At 0 d to 7 d of aging,the immobilized water transferred to bound water and the WHC was decreased.At 7 d to 14 d of aging,the bound water transferred back to immobilized water and increased.At 21 d to 28 d of aging,the immobilized water converted into free water at this aging stage with a decrease of WHC.The results of protein secondary structure demonstrated that compared with aging for 7 d,the disordered structure of protein in wet-aging group,RH80 dry-aging group and RH60 dry-aging group reduced by 9.2%,14.1%,and 17.3% at aging 14 d respectively,which indicated that the lamb had a better protein stability and WHC at aging 14 d.(2)The variation of lamb flavor precursors during dry aging was analyzed.The study was assigned lamb gigots randomly into wet aging,RH80 dry aging and RH60 dry aging to analyze protein content,fat content,free amino acid,volatile compounds and flavor precursors at aging 0 d,7 d and 14 d.The results were shown,a total of 14 key volatile flavor compounds in dry aged lamb were identified,which were hexanal,heptanal,octanal,(E)-2-Nonenal,nonanal,(E)-2-nonenal,(E,E)-2,4-nonadienal,decanal,(E,Z)-2,4-decadienal,(E,E)-2,4-decadienal,1-Octen-3-ol,1-heptanol,1-octanol and 2-pentyl-furan.The hexanal,octanal and 1-octene-3-ol played an important role in dry aged lamb flavor.The pathway of metabolic analysis showed that the different metabolic pathway of the aged lamb was phenylalanine,tyrosine and tryptophan biosynthesis.The different metabolic pathways of RH80 dry aged lamb was alanine,aspartate and glutamate metabolism,fructose and mannose metabolism.The different metabolic pathways of RH60 dry aged lamb was arginine biosynthesis,2-oxocarboxylic acid metabolism and purine metabolism.The different metabolic pathways of dry aged lamb were mostly the pathways of umami and sweet substances,which played a major regulatory role in flavor precursors formation.(3)The cooking characteristics and suitability of dry aged lamb were clarified was analyzed.The lamb gigots were assigned randomly into wet aging,RH80 dry aging and RH60 dry aging and then selected the knuckle at aging 0 d,7 d and 14 d.The samples were cooked by four cooking methods(hot pot,stir fry,grill and boiling)to analyze cooking loss,texture profile,flavor,taste and sensory characteristics.The results were shown,the meat quality of RH80 dry aged lamb using four cooking methods was better than RH60 dry aged lamb and wet aged lamb.The lamb in RH80 dry aging for 7 d or14 d had rich aromatic compounds and umami taste than wet aged lamb.The results of sensory evaluation showed that samples in RH80 dry aging for 7 d was suitable for stir fry,boiling and grill while it was fit for hot pot and grill after aging for 14 d.