| Rice flavor Baijiu is one of the five traditional flavor Baijiu in China,which has a profound cultural heritage and a long production history.The traditional rice flavor Baijiu production technology is solid fermentation or semi solid liquid fermentation,but the traditional fermentation method has problems such as low liquor yield,difficult sampling,and uneven distribution of fermentation bacteria;The use of liquid fermentation technology can effectively improve the shortcomings of traditional fermentation methods.This paper uses separate liquefaction,saccharification,and alcoholic fermentation experiments to study the changes in various physical and chemical indicators and microbial diversity during the fermentation process.The main research content and results are as follows:(1)Study on optimization of liquefaction conditions:The traditional Rice noodles mixing and heating will cause the problem of thick and non fluidity of rice starch,so we chooseα-Amylase is used for liquefaction.Prior to liquefaction,a fermentation experiment was conducted to determine the more suitable material water ratio of indica rice:water=1:2.5(mass ratio).Then,single factor experiments and orthogonal experiments were conducted to detect the reducing sugar content and DE value of the liquefaction liquid,and the optimal material water ratio was determinedα-The addition amount of amylase,liquefaction temperature and liquefaction time were 15 U/g Rice noodles,80℃-85℃and 120 min,respectively.(2)Research on saccharification process:Saccharification is an important step in liquid fermentation,and both saccharifying enzymes and saccharifying koji can further saccharify the liquefied liquid.However,the saccharification effect and product content of saccharifying enzymes and saccharifying koji are different.Therefore,using indica rice as raw material and liquid fermentation technology,this study explores the selection of saccharifying enzymes and saccharifying koji during the saccharification process of rice wine,as well as the use of breathable membranes and kraft paper with breathable membranes for sealing during the saccharification process The selection and dosage of saccharification koji,as well as the accumulation of substances such as glucose,lactic acid,and acetic acid during the saccharification process.The results showed that the saccharification effect of saccharifying koji was better,with a saccharification rate of 72.77%,acetic acid and lactic acid contents of4.82 g/L and 6.45 g/L,respectively,which were 159.7%and 223.5%higher than that of saccharifying enzyme saccharification solution,respectively;At the same time,other saccharification conditions are:sealing with breathable film,saccharification with composite saccharification koji,and adding 2%saccharification koji.Under these conditions,the reduced sugar content of the saccharification solution obtained is163.14 g/L,glucose content is 159 g/L,lactic acid content is 9.88 g/L,and acetic acid content is 6.93 g/L.The saccharification solution obtained under these conditions is suitable for subsequent alcoholic and esterification processes,providing a prerequisite for ensuring that the obtained rice wine reaches the corresponding alcohol content and flavor substances.(3)Study on the Liquification Process:Activate and cultivate three yeast strains stored in the laboratory,measure the growth curve of the activated yeast strains,determine the logarithmic growth end stage of the three yeast strains,and ferment the yeast strains at this time.Pure strain fermentation is carried out on the three yeast strains,and the sugar alcohol conversion,ethanol generation rate,ethyl acetate and the accumulation amount ofβ-Phenylethanol was compared with the fermentation effect of three kinds of yeast.The results showed that when the addition amount of Saccharomyces cerevisiae 8Y3,Cyberlindnera fabianii 11Z1 and Saccharomyces cerevisiae GGSF-16 was 2×10~6cfu/m L、5×10~6cfu/m L、1×10~7cfu/m L,the fermentation effect was more prominent,but the flavor and taste were not coordinated.Therefore,it was decided to mix three types of yeast for pure yeast mixed fermentation,and at the same time,design and add appropriate nitrogen sources to improve yeast growth,metabolism,and fermentation efficiency.When the ratio of the three types of yeast was 8Y3:11Z1:GGSF-16=2:1:1,and the nitrogen source addition amount was 3 g/L,the fermentation effect was better.There were high concentrations of ethanol,ethyl acetate,and the accumulation ofβ-Phenylethanol was 11.71±0.28%vol,1599.11±67.35 mg/L,and 340.59±3.06 mg/L,respectively.(4)Research on pure bacterial mixed fermentation and 5 L tank fermentation:After obtaining the above relevant fermentation conditions,conduct a study on the mixed fermentation of pure strains of saccharifying bacteria and alcoholic bacteria.Firstly,by measuring ethanol,ethyl acetate,ethyl lactate,and the accumulation ofβ-Phenylethanol was investigated,including the mixing method and the amount of lactic acid added.Finally,a 5-L tank fermentation experiment was conducted,and samples were taken to detect changes in the microbial colonies during the fermentation process.After the fermentation was completed,the fermentation broth was subjected to physicochemical analysis and volatile flavor substance quality determination.The results showed that when the amount of lactic acid added was0.06%,the fermentation method of simultaneous saccharification and alcoholic fermentation had a better fermentation effect,with the highest accumulation of ethyl lactate reaching 208.15±3.54 mg/L,which was 155.88%higher than the blank control group;During the fermentation process,the colony changes were as follows:at the initial stage of fermentation,the accounted of Cyberlindnera fabianii 11Z1 for a large proportion,and with the increase of fermentation time,the saccharifying bacteria content gradually increased,while the Cyberlindnera fabianii 11Z1 died rapidly and massively,the abundance of Aspergillus niger and Saccharomyces cerevisiae Saccharomyces increased,while the abundance of Cyberlindnera fabianii Saccharomyces decreased;Its physicochemical indicators are:alcohol content is12.75±0.07%vol,alcohol yield is 76.47±5.08%,residual total sugar is 10.53±0.7g/L,p H is 4.51±0.14,total acid content is 5.83±0.37 g/L,amino acid nitrogen content is 2060±140.45 mg/L,and overall sugar utilization rate is 89.79±1.19%;The main aroma substances are:the accumulation of ethyl acetate is 1543.51±17.76mg/L,and the accumulation of ethyl lactate is 155.93±5.6 mg/L,the accumulated amount ofβ-Phenylethanol is 258.42±7.91 mg/L,and all indicators comply with national standards. |
PDF Full Text Request