Study On Alliin And Main Related Sulfides In Hot-processing Of Black Garlic

Black garlic is a kind of garlic deep-processed product,which is made from fresh garlic under high temperature and humidity conditions for a certain period of time.After garlic is prepared into black garlic,its pungent odor is removed,and the taste and nutritional value of garlic are significantly improved.The alliin and its related sulfides in black garlic give black garlic special functionality.At present,there are increasing researches on the health functions of black garlic and alliin.However,the research which is about the changes in the content of alliin and related sulfides during the processing of black garlic is still at a blank stage.Based on the establishment of an efficient detection method for alliin and its related sulfides in black garlic,this study optimizes black garlic processing technology step by step through single factor experiment to improve the quality of black garlic.At the same time,the changes of alliin and its related sulfides in black garlic under different storage conditions are investigated by the study.The main research conclusions of the thesis are as follows:Firstly,the extraction conditions of alliin and related sulfides in black garlic were optimized,and the detection method for simultaneous determination of alliin and related sulfides in black garlic was determined.And the method improved the detection efficiency.The effectiveness of the detection method showed that the correlation coefficients(R²)of alliin,S-allyl-L-cysteine and?-glutamyl-cysteine in the linear range were 0.9992,0.9991 and 0.9988respectively,and its linear relationship was good,the detection limits are 0.17?g·m L^-1,0.12?g·m L^-1,0.31?g·m L^-1 respectively,the recovery rate of standard addition is 92.00%-95.47%,which can fulfill the qualitative and quantitative detection requirements of alliin and its sulfur-containing compounds in black garlic.The thesis measured the quality indicators of 13 types of commercially available black garlic samples,and determined the browning degree range of commercially available black garlic is 70-76,the hardness range of the texture index is 30-35 N,and the elasticity range is0.8-1.0 mm.The range of chewiness is 7-9 N·mm,the range of total sugar content is 150-170mg·g^-1,and the range of polyphenol content is 8.0-9.5 mg·g^-1.The thermal stability of?-glutamyl-cysteine is better than that of alliin and S-allyl-L-cysteine.Alliinase,?-glutamyl transpeptidase and?-glutamylcysteine synthetase are completely inactivated in heating at 50?for 18 h,which indicates that the three enzymes may have been completely inactivated before the 0-34 h stage of black garlic processing,and will not affect the changes of alliin and related sulfides in the subsequent stages.The research on the processing process of black garlic shows that the browning degree,texture,total sugar,polyphenols,alliin and its related sulfides contents and other quality indicators changed significantly during the maillard reaction stage(the days of 6th to 14th).Based on the results of single-factor test,the processing conditions of black garlic after gradual optimization are that the processing humidity is 80%,the processing temperature is70?,and the processing time is 180 h(7.5 days).The total content of alliin and its related sulfide components increased by 20.1%.The sensory evaluation results showed that the black garlic samples scored higher in color,dryness,garlic meat texture,smell,mouthfeel,etc.After the process optimization,and the sweet and sour taste of black garlic was more coordinated,and its bitterness was significantly reduced.This further shows that the optimized process parameters not only increase the content of alliin and its related sulfide components,but also have a significant promoting effect on improving the overall quality of black garlic products.Finally,the storage experiment of black garlic samples showed that natural light irradiation and cold storage under vacuum at 4?can save costs and reduce the loss of alliin and its related sulfides better,which is beneficial to maintain the quality of black garlic.