Influence Of Fumigation Process On Contents Of Ligstrazine And Acrylamide In Vinegar

Shanxi aged vinegar is a kind of smoked vinegars.The fumigation process is the distinctive core procedure.Fumigating process is mainly occurred the Maillard reaction,one of the products of this reaction is ligustrazine,and it has the function of lowering blood pressure,resisting thrombus and so on.In addition,another possible product of the reaction is acrylamide,it is suspected human carcinogens,but whether there is the substance and its determination method in smoked vinegar has not been reported.Therefore,explored the ligustrazine and acrylamide formation regularities and influence factors of fumigating process and established the acrylamide detection method have the vital significance for the functional and safety evaluation of vinegar fumigating and fumigating condition optimization.The somked vinegar and the smoked grains were selected as the research object.Analyzing the influences of different fumigation processes on content of ligstrazine and acrylamide by high performance liquid chromatography(HPLC).The research and results were as follows:(1)Through screening detection wavelength,flow velocity,flow phase and the proportion,the HPLC chromatographic conditions of acrylamide content determination was established,which used methanol/water(10:90,V/V)as mobile phase at a flow rate of 0.4mL/min and the wavelength of 238nm,analyzed by Diamondil C18(4.6x250mm,5μm)reverse phase column under room temperature,and the sample volume was 20μL.Samples of vinegar smoked grains were extracted with water and cleaned up by HLB solid phase extraction column before chromatographic determination.The calibration curve was linear in the ranges of 0.05-10.00μg/mL,the detection limit was 15ng/mL and the recovery was 95.19-105.85%,the RSD of inter-day and intra-day precision was 2.90%and 4.23%,respectively.(2)HPLC method was adopted to measure the content of acrylamide and ligustrazine in vinegar.Results showed that the content of acrylamide and ligustrazine was 4.95-25.50μg/L and 28.36-85.11mg/L respectively,and the content of ligustrazine of many years aging vinegar was much higher than that untreated vinegar.Through correlation verification analysis,the ligustrazine and acrylamide in vinegar were both derived from Maillard reaction.(3)HPLC method was adopted to measure the content of acrylamide and ligustrazine in smoked grains.The effects on Maillard reaction and its products of different fumigating conditions(temperature and time)was explored and the results showed that the content of ligustrazine and acrylamide increased at first and then decreased with the increase of temperature and time(within the range of 120-180℃and 0-11h).The highest yield of ligustrazine appeared at 120℃while heating 11h,and the acrylamide appeared at 160℃while heating 2.5h.In addition,the time of occurrence of the maximum amount of acrylamide would shorten with the increase of temperature.Within the range of 90-120℃,the content of ligustrazine and acrylamide gradually increased with the increase of temperature and time during fumigating,and the production of ligustrazine and acrylamide showed a positive correlation,however the acrylamide needs higher fumigating temperature than ligustrazine while generating.The color quality of vinegar can be well reflected by the brown degree.Analyzing the correlation of content of ligustrazine and acrylamide and brown degree,it was found that the Maillard reaction occur in the process of fumigating,both ligustrazine and acrylamide were products of Maillard reaction.Therefore,elevating temperature can improve the extent of the Maillard reaction.However the temperature of fumigation should not be too high,in terms of ligustrazine content the fumigating temperature should not higher than 120℃and acrylamide content not higher than 100℃.(4)Exploring the influence of different fumigation processes(steam fumigation and traditional charcoal fumigation)on Maillard reaction and the content of ligustrazine and acrylamide of smoked vinegar.The study showed that the rate of steam fumigation can accelerate the Maillard reaction than charcoal fumigation in the same conditions,moreover,the content of ligustrazine was significantly higher in steam fumigating than charcoal fumigation.Whether the traditional charcoal fumigation or steam fumigation,acrylamide could not be detected until 90 ℃ fumigating to 5d,which showed that low-temperature fumigation was propitious to avoid the generation of acrylamide.Accordingly,in the premise of fumigation under low temperature,compared with traditional charcoal fumigation,steam fumigation can not only avoid the production of acrylamide,but also facilitate the formation of ligustrazine.The low temperature steam fumigation technology had a great potential for popularization and application.