Study On Key Bitter Compounds And The Influencing Factors In Trasitional Shaoxing-jiu

Traditional Shaoxing-jiu,with mellow and full-bodied aroma,mild and sweet taste,and slight bitterness,occupies an important share in the rice wine market due to its superior flavor quality.However,the natural and open fermentation of traditional Shaoxing-jiu is prone to cause the problem of ustable flavor quality of products from different batches,making the mass production of Shaoxing-jiu with outstanding quality difficult to maintain.One of the common problems that the characteristic bitterness of Shaoxing-jiu may easily transform into an unpleasant “after-bitterness”,affecting consumers' acceptance of Shaoxing-jiu and restricting the market expanding.To ascertain how the process parameters affect the bitterness of Shaoxing-jiu and improve the stability of flavor quality of products from different batches,it is necessary to investigate the bitterness characteristics and composition of traditional Shaoxingjiu through modern flavoromics technology.This project reveals the bitterness characteristics and main compound source of traditional Shaoxing-jiu by establishing the methods of bitter taste evaluation the determination of the main bitter compounds,and then studies the important process parameters in the production process,eventually proposes the production programme to optimize the flavor quality.The main conclusions of this research are as follows:(1)Firstly,the descriptors of traditional Shaoxing-jiu taste characteristics were ruled by descriptive sensory evaluation,and the influence of bitterness on overall taste was clarified by quantitative descriptive analysis.Secondly,TCATA(temporal check-all-that-apply)test,TDS(temporal dominance of sensation)test,and TI(time-intensity)test were adopted to analyze of dynamic change of traditional Shaoxing-jiu taste during drinking,exposing the dominance of bitterness during drinking.Then electronic tongue was employed to examine the results of artificial sensory evaluation on Shaoxing-jiu taste,and to establish the standard curve of quinine sulfate-electronic tongue bitterness response.Consequently,the approach to evaluating the bitterness of Shaoxing-jiu has been constructed through artificial sensory evaluation and electronic tongue technology.(2)The 18 main volatile bitter compounds and 17 free amino acids in traditional Shaoxingjiu were determined by GC-MS(gas chromatography-mass spectrometry)and HPLC(high performance liquid chromatography).On this basis,10 key bitterness compounds: isobutyl alcohol,isoamyl alcohol,1-hexanol,phenethyl alcohol,ethyl acetate,ethyl butyrate,ethyl lactate,furfural,arginine and valine were identified through recombination and omission experiments.Consequently,the approach to determining the key bitterness compounds of traditional Shaoxing-jiu has been constructed.In addition,the amino acid sequence Leu-ProThr-Leu of the key bitterness peptide of traditional Shaoxing-jiu was identified by combining ultrafiltration,gel filtration chromatography,high performance liquid chromatography,ultra performance liquid chromatography-quadrupole-time of flight mass spectrometric with taste dilution analysis and addition experiments.(3)Base on the above-mentioned approaches to evaluating the bitterness and determining the key bitterness compounds,the bitter compounds and bitterness of Shaoxing-jiu brewed with different raw rice,different ambient temperature,and aged with different years were determined.The results indicated that,the bitter compounds in Shaoxing-jiu brewed with sticky rice had lower contents than those brewed with polished round-grained rice;taking the days before winter solstice as the time node to start the brewing was prone to produce the Shaoxing-jiu with a more harmonious flavor and softer bitterness,than the days after the vernal equinox;longer aging time was beneficial to improve the flavor quality of Shaoxing-jiu.These conclusions provide a theoretical basis for the regulating the traditional Shaoxing-jiu taste quality from the perspective of production process parameters,and also provide references for improving the quality stability of traditional Shaoxing-jiu from different batches...