Effect Of Low-temperature Pre-heating After Slaughter On Meat Lipid And Flavor Of Raw Materials Of Yellow Feathered Broilers

Lipid is an important nutrient element and flavor precursor of meat.Pretreatment of raw meat affects the lipid content and lipid molecular types in meat,and then affects the flavor and quality of chicken.On the basis of previous research,this paper first studied the influence of low-temperature heating and inactivating enzyme treatment on the lipid composition of raw meat of chilled yellow-feathered broilers compared with pre-cooling water treatment,and then studied its influence on flavor substances in yellow-feathered broilers.On this basis,it explored the influence of low-temperature heating and inactivating enzyme treatment on the flavor of chicken soup stewed from raw meat of chilled yellow-feathered broilers.The main research contents and conclusions are as follows:(1)Effect of low temperature heating and inactivating enzyme pretreatment on lipid composition of yellow-feathered broilers during cold storage.By liquid chromatography-mass spectrometry(LC-MS),the lipid proteomics of chicken in lowtemperature heating group(group H)and pre-cooling group(group P)was quantitatively analyzed,and the changes of lipid types and contents during cold storage were clarified,and the differences of lipid molecules were compared.By detecting the enzyme activity of lipid hydrolase,lipid oxidation and the growth of spoilage microorganisms,the causes of lipid changes in chicken during cold storage were explored.The results showed that 492 kinds of lipid molecules and 13 kinds of lipid subclasses were detected in the breast meat of yellow-feather broilers,and Triacylglycerols(TAG)was the highest in group H and group P.The lipid molecules containing 18: 1,18: 2 and 20: 4 fatty acid chains in yellow-feathered broilers were more easily degraded during cold storage.During 6 days of cold storage,the total lipid content in chicken breast meat in group H decreased by 12.64% and that in group P decreased by 16.86%.TAG,Phosphatidylcholines(PC)and Phosphatidylethanolamines(PE)are the main lipid subclasses decreased in chicken meat,while free fatty acids are the main lipid subclasses increased in chicken breast meat in group H,while lysophosphatidylcholine,lysophosphatidylethanolamine and sphingomyelin are the main lipid subclasses increased in group P.(2)Effect of low temperature heating and passive enzyme pretreatment on flavor of yellow-feather broilers during cold storage.Headspace solid-phase gas chromatography-mass spectrometry(HS-GC-MS)was used to detect volatile flavor compounds in chicken breast.By measuring the contents of free amino acids and flavorpresenting nucleotides,the changes of flavor compounds in group H and group P were analyzed,and the flavor quality of chicken breast was comprehensively evaluated by principal component analysis.The results showed that 38 kinds of volatile flavor compounds were detected in yellow-feathered broilers,among which alkanes and aldehydes accounted for a large proportion.On the 0 th day,the contents of nonanal and decanal in chicken in group H were higher than those in group P,and the content of 1-octene-3-ol in group P was 1.01 μg/g,which was 0.47 μg/g higher than that in group H.After 6 days of cold storage,the contents of decanal,nonanal,hexanal and 2-bromooctadecanal in group P were higher than those in group H.By ranking the volatile flavor substances by the comprehensive score of principal components,it was found that the smell quality of chicken in group H was better than that in group P on the 0 th day.In addition,17 kinds of free amino acids were detected in yellow-feathered broilers.The total amount of free amino acids in group H was always lower than that in group P during cold storage.After six days of cold storage,the contents of umami and bitter amino acids in group P were higher than those in group H.The Taste activity value(TAV)of taste-presenting nucleotide II and amino acids were evaluated.It was found that the TAV values of 5 ′-Inosine 5’-monophosphate(IMP),glutamic acid and histidine were greater than 1,which contributed greatly to the taste of chicken.By ranking the flavor active substances by the comprehensive score of principal components,it was found that the taste quality of group H was better than that of group P on the 0 th and 6th day,which indicated that low-temperature heating and inactivating enzyme treatment was beneficial to maintain the flavor substances of yellow-feathered broilers.(3)Effect of low temperature heating and inactivating enzyme treatment on the flavor of yellow-feathered broilers soup.The volatile flavor substances in chicken soup were analyzed by HS-GC-MS,and the free amino acids,nucleotides and other flavor substances in chicken soup were determined,and the comprehensive evaluation was made by principal component analysis.The results showed that 30 volatile flavor compounds were detected in chicken soup.Aldehydes are the most volatile flavor compounds.On the 0 th day,the contents of nonanal,(Z)-7-hexadecenal and heptanal in group H were lower than those in group P,and the contents of hexanal were lower than those in group P after 6 days of cold storage.The content of arginine in group H was lower than that in group P on the 0 th day,and significantly higher than that in group P on the 3 rd and 6 th days.After 6 days of refrigeration,the contents of alanine and glycine in chicken soup in group H were higher than that in group P.IMP is the main flavor substance of chicken soup,and its TAV is greater than 1.The IMP of chicken soup in group H was significantly higher than that in group P during cold storage.The comprehensive score of taste substances in chicken soup is P0 > H0 > H3 >P3 > H6 > P6,which shows that the flavor of chicken soup stewed after the third and sixth days of cold storage with low-temperature heating and inactivating enzyme is better than that of chicken soup cooked with precooled chicken.