| In traditional yellow rice wine production technology,the quality of rice wine are susceptible to could quality and the influence of material properties,this paper in yellow rice wine multi-molds（Rhizopus chinonsis R01,Asperigillus niger A20,Mucor pusillus M05 and Saccharomyces cerevisiae S10）based on mixed fermentation,with japonica rice and black rice as raw material,studied in many species and enzyme preparation distribution as the initial preparation of yellow rice wine was studied.Meanwhile,the pretreatment and fermentation process of black rice were studied by using the compound starter culture.The main research results were as follows:The effects of enzyme preparation（high temperature resistantα-amylase,saccharifying enzyme and acid protease）on raw material,fermentation process,composition and flavor of rice wine were studied with japonica rice as raw material.The results showed that the addition of amylase（AM）,glucoamylase（GAM）and acid protease（AP）could increase the alcohol content by 49.22%to 15.35%（v/v）.The content of free amino acids increased by 85.54%to 3.136 mg/L.The content of flavor compounds increased by 25.71%to 428.79 mg/L.In order to show the principle of action of the enzyme,the effects of the enzyme on the physicochemical properties of rice,microbial growth and enzyme production were analyzed.AM formed micropores on the surface of rice grains,significantly reduced the hardness of rice grains,expanded the reaction area and was beneficial to further hydrolysis.After the rice grain is hydrolyzed,a large amount of hydrolysate,total sugar and amino nitrogen was produced,which was beneficial to the growth of microorganisms and reduced the viscosity of the system.AM was beneficial to the amylase activity of R.chinensis R01and A.niger A20.GAM and AM have certain synergistic effect and accelerated the hydrolysis of rice.GAM significantly promoted the growth of S10.AP could promote protease activity of M.pusillus M05 and A.niger A20,improved protein utilization and enhanced flavor.Black rice has a thick aleurone layer structure,which leads to slow water absorption,difficult cooking and low fermentation speed.The cooking performance of black rice was improved by pretreating it before cooking.The effects of pre-gelatinization（PG）and pre-cellulase treatment（PCE）on cooking performance and fermentation performance of black rice were studied.The results showed that the integrity and structural stability of black rice could be destroyed by pre-gelatinization（treatment at 60℃for 60 min）and pre-cellulase treatment with cellulase.Compared with the control group,the contents of ethanol,free amino acids and volatile flavor substances in the combined pretreatment（PGPCE）group were increased by 19.02%,23.54%and 33.89%,respectively.Low field nuclear magnetic（LF-NMR）,SEM and other analyses showed that pre-gelatinization and pre-cellulase treatment could improve water absorption performance of black rice,increase starch gelatinization degree,promote substance dissolution,increase reaction area and system fluidity,promote biotransformation of substances in the fermentation process,increase the content of active substances,and shorten the early fermentation time.Adding cellulase（45 U/g）at the beginning of fermentation could increase ethanol yield,amino acid content,volatile flavor compounds and antioxidant activity,which were increased by 90.81%,15.36%,44.16%and 19.56%compared with the control,respectively.LF-NMR,DSC and SEM analysis showed that cellulase hydrolysis destroyed the structure of black rice aleurone layer,was beneficial to water precipitation,improved the fluidity of the system,significantly increased the reaction area and precipitate content,and promoted the precipitation of anthocyanins,phenols and other active substances.The combination of pre-gelatinization and cellulase hydrolysis（PGCE）can further improve the fermentation performance of black rice rice wine,increase the nutrition of black rice wine,and endue the black rice wine with better quality.Soaking rice water is the main contaminant in rice wine production.The soaking process of black rice was determined:soaking for 2 days at 20℃and the ratio of material to water was 1:1,the amount of rice water produced by this process was less.Added soaking rice water（0.5 times the weight of black rice）in the fermentation process could not only make resource utilization of rice water,but also improve the quality of black rice wine.Compared with the control,the contents of amino nitrogen,ethanol and total sugar in rice wine increased by 3.98%,9.40%and 25.58%,respectively.The antioxidant contents of anthocyanins,total flavonoids and total phenols were increased by 31.58%,15.86%and 16.22%compared with the control,respectively.The amino acid analysis showed that the addition of rice water could reduce the proportion of bitter amino acids in black rice wine,increase the content of sweet amino acids,and give the black rice wine better taste and color.The stability analysis of anthocyanins in black rice wine showed that the methods of reducing the infiltration of metal ions(especially Fe3+),reducing light,adding stabilizer at low pH and so on were helpful to the retention of anthocyanins. |
