Studies On Optimization Of Slaughter Processes And Comparison Of Volatile Compounds On Layer And Broiler Chickens

Taking rejected layer and AA broiler as the object of the research, the effects of shackling times and scalding temperatures on meat quality in layer and broiler chickens after slaughter were studied. Chicken quality is expressed by these indicators, including pH, color, water holding capacity, T2b and T21 peak area, inosinic acid (IMP) content. Meanwhile, in order to improve rejected layer’s utilization, it is necessary to explore its flavor sources and main flavors. The experiments and results are as follows:The effect of shackling times on meat quality in layer and broiler chickens after slaughter was studied by the means of a split plot experiment. Two chicken species (rejected layer, AA broiler) and five shackling times (0,30,60,90 and 120 s) were included in this study. This study is expected to offer data guide and help to halal slaughter enterprises in China. The results showed that when AA broiler was shackled at 90 s, these indicators, including deep-body temperature, pH2 value, a* value, drip loss, cooking loss, T21 peak area and IMP content, all increased significantly, while IMP content decreased significantly, when rejected layer was shackled at 120 s, pH2 value, a* value and cooking loss increased significantly, IMP content decreased significantly. GLM-Multivariate analysis results showed that species had a significant influence on deep-body temperature, L* value, drip loss, cooking loss, T2b peak area, T21 peak area and IMP content. Shackling time had a significant effect on all of the indicators, except pH1, pH2 value, L* value, a* value, Tab and T21 peak area. Interactions between species and Shackling time significantly affected a* value, drip loss and IMP content. Combined with document, it was recommended that the optimum shackling time of AA broiler should range from 12 to 60 s, while one of rejected layer should range from 12 to 90 s.The effect of scalding temperatures on meat quality in layer and broiler chickens after slaughter were studied by the means of a split plot experiment. Two chicken species (rejected layer, AA broiler) and five scalding temperatures (50,55,60,65 and 70℃ were included in this study. This study is expected to offer data guide and help to halal slaughter enterprises in China. The results showed that with scalding temperature increasing, pHi in rejected layer and AA broiler decreased, but their pH2 had no significant variance. L* value increased, while a* and b* value decreased. Drip loss and cooking loss all increased. Scalding temperature had a markedly effect on T21 peak area, instead of T2b peak area. IMP content of AA broiler nearly kept steady, while IMP content of rejected layer decreased. GLM-Multivariate analysis results showed that species had a significant influence on L* value, a* value, drip loss, cooking loss, T2b peak area, T21 peak area and IMP content. Scalding temperature had a significant effect on all of the indicators, except pH2 value and T2b peak area. Interactions between species and scalding temperature significantly affected a* value, b* value, drip loss and T21 peak area. In conclusion, taking various factors into consideration, it will contribute to improving chicken quality after slaughter, when AA broiler is scalded at (50-55)℃, and rejected layer is scalded at (50-55)℃.The volatile components of breast muscle of rejected layer and AA broiler were extracted by head space solid-phase micro-extraction (HS-SPME), and identified by gas chromatography-mass spectrometry (GC-MS). The results show that a total of 39 volatile compounds were identified in rejected layer, including 2 aldehydes,26 hydrocarbons,3 alcohols,1 ketones,5 esters,1 ethers,1 nitrogenous compounds. And 33 volatile compounds were detected in AA broiler, including 7 aldehydes, 11 hydrocarbons,4 alcohols,2 ketones,7 esters,1 ethers,1 nitrogenous compounds.15 substances are commonly identified, including hexanal, nonanal,2,3-octadione,2,6,10-trimethyldo-decane, 2,6,10,14-tetramethylpentadecane, tetradecane, pentadecane, hexadecane, nonadecane, dimethyl phthalate, tributyl phosphate, diethyl phthalate, diisobutyl phthalate, diisooctyl phthalate, decyl ether.