Study On The Quality Of Mutton And Its DNA Under Different Storage Conditions

In order to investigate the changes in physicochemical properties and DNA quality of mutton during storage under different temperatures(-20 ?,4?,10? and 20 ?).Physicochemical properties,including TVB-N,pH,moisture content,water holding capacity(WHC),L*,a*,b*,texture(hardness,elasticity,cohesiveness,chewiness,resilience),crude protein content,crude fat content,total fatty acids,saturated fatty acids(SFA),monounsaturated fatty acids(MUFAs),polyunsaturated fatty acids(PUFAs)and the microstructure of muscle fibers,were evalluated.DNA quality,including DNA integrity,yield,purity and mtDNA:nDNA,were also measured.Furthermore,the correlation and factor analysis were conducted to analyze the relationships between 18 physicochemical indices and DNA quality and determine the main and referencedetection indices for the assessment of mutton quality.This study aimed to provide scientific basis and standard method for selecting mutton storage conditions and predicting shelf life.The main results were as follows:(1).Storage influenced mutton physicochemical quality.The TVB-N value increased during storage at all temperatures(P<0.05).The TVB-N value reached 15mg/100g when mutton was stored at-20?,4?,10? and 20? for 3 months,2 days,24 hours and 8 hours,respectively.The TVB-N value was over the requirement of national standard of 25mg/100g when mutton was stored at-20?,4?,10? and 20? for 11 months,5 days,60 hours and 24 hours,respectively.The pH value declined at first and then increased,it reached the lowest value when mutton was stored at-20?,4?,10? and 20? for 3 months,2 days,24 hours and 8 hours,respectively.While the L*,a*and b*values increased and then declined.The water holding capacity,hardness,elasticity and chewiness decreased during storage.Cohesiveness and resilience remained stable during storage.The microstructure of muscle fibers became loose as storage time extended.(2)Storage influenced mutton nutrient content.The moisture content,protein content,fat content,total fatty acids,SFA,MUFA,and PUFA decreased during storage.(3).Storage influenced DNA quality.DNA content decreased at first and then increased,while the ?Ct value firstly increased and then decreased.The DNA purity have no significance change.The agarose gel electrophoresis results showed that the DNA bands became fainter with storage time extended.Goat FABP3 gene was successfully amplified from all samples.(4)Correlation and factor analysis of storage time and physicochemical indexes were performed under different storage conditions.The detection system was established for mutton quality assessment under different storage conditions.The moisture content,water holding capacity,pH,fatty acid and crude fat content were used as the main indices.TVB-N content,color difference,while TPA and crude protein content were used as reference indices.Then,correlation analysis between DNA quality and indexes(the moisture content,water holding capacity,pH,fatty acid and crude fat content).