Study On Reduction And Control Of Capsaicinoids In The Processing Of Marinated Duck Neck And Rapid Detection Technology

Capsicum is one of the most important spices in the world and its strong stimulating properties are attributed to capsaicinoids,of which capsaicin and dihydrocapsaicin account for more than 90%.The content of capsaicinoids in the processing of soy-marinated duck necks varies greatly with the brining time,brining batch and processing process,and can not be controlled online due to the lack of capsaicin rapid detection technology.In this paper,we investigated the changes of capsaicin and dihydrocapsaicin contents in soy-marinated duck necks under different brining times and processing processes,regulated by changing the sterilization method and evaluated the results by the two-three point test.An electrochemical sensor based onβ-cyclodextrin(β-CD)and reduced graphene oxide(r GO)was constructed,characterized and optimized in terms of preparation parameters for the rapid and accurate detection of capsaicin content.The identification mechanism and reaction type of capsaicin detection were investigated,and the scientific validity and accuracy of the method were verified by spiked recovery experiments and comparison with LC-MS results.The results of the study are as follows:(1)The variation of capsaicinoids content in braised duck neck during processing is as follows:the contents of capsaicin and dihydrocapsaicin in the soy-marinated duck necks increased with the increase of brining time,which was consistent with the trend of capsaicinoids in the brine soup,and the migration of capsaicinoids from the brine to the duck necks was faster in the first 20 min,with the migration ratios of 71.8%and67.3%,respectively.There was a significant difference in the capsaicinoids content of soy-marinated duck necks after brining,roasting and sterilization treatments,with autoclaving resulting in a 33.1%and 45.1%reduction in capsaicin and dihydrocapsaicin content,respectively.During sterilization and storage,some of the capsaicinoids in the duck neck meat migrated to the bones.(2)By changing the processing technology of braised duck neck,the content of capsaicinoids was regulated and the results were as follows:Under low temperature sterilization at 80℃,medium temperature sterilization at 95℃and 105℃and high temperature sterilization at 121℃,the content of capsaicinoids in duck neck decreased by 3.2%,16.9%,22.3%and 35.5%,respectively,compared with the samples before sterilization,which indicated that capsaicin and dihydrocapsaicin were more stable and less susceptible to thermal decomposition within 100℃.As the sterilization temperature increased,there were significant differences in the physicochemical indexes and color of the soy-marinated duck necks,including an increase in moisture content,protein and crude fat content,a slight decrease in p H,and no significant difference in color.After correlation analysis and ANOVA,the results showed that the content of capsaicinoids in duck neck was significantly and positively correlated with p H(P≤0.01),a significant negative correlation with a~*and b~*(P≤0.01),and a significant positive correlation with L~*(P≤0.05),and the color of duck neck could reflect its pungency degree.The results of the two-three point sensory evaluation showed that the spiciness of the soy-marinated duck necks under low temperature sterilization at 80°C and medium temperature sterilization at 95°C was not significantly different from that of the unsterilized samples,and it was feasible to regulate their spiciness by changing the sterilization conditions.(3)The structural characterization and electrochemical characterization results are as follows:the addition ofβ-CD during the preparation ofβ-CD/r GO/GCE could disperse r GO and increase the electrochemically active surface area ofβ-CD/r GO,thus improving the electron transfer rate.Meanwhile,the poly-β-CD on the r GO surface could recognize and enrich the capsaicin on the electrode surface,thus improving the detection performance ofβ-CD/r GO/GCE.The electrochemical redox reaction of capsaicin on theβ-CD/r GO/GCE sensor was found to be jointly controlled by adsorption-diffusion and mainly by diffusion,and the reaction process was the interconversion of o-benzoquinone and o-phenol structures with the participation of two electrons and two protons.(4)Based on cyclic voltammetry and differential pulse voltammetry,the performance ofβ-CD/r GO/GCE was studied and the methodological evaluation results were as follows:The performance and methodology evaluation ofβ-CD/r GO/GCE based on cyclic voltammetry and differential pulse voltammetry:To improve the performance of theβ-CD/r GO/GCE sensor for capsaicin detection,the parameters of solution p H,GO concentration,deposition potential,number of scanning segments and scanning speed were optimized,and the linear range of capsaicin detection was 0.1～40μg/m L and the detection limit was 0.05μg/m L with good reproducibility,stability and interference resistance after optimization.When theβ-CD/r GO/GCE sensor was applied to the determination of capsaicin content in pepper oil,the spiked recoveries ranged from 95.54%to 118.65%with the relative standard deviations less than 10.69%,and there was no significant difference(P≤0.05)when compared with the LC-MS results,which indicated the feasibility of using this method for real sample detection.