Study On Cooking Quality And Fermentation Characteristics Of Brewed Sorghum

Sorghum(Sorghum bicolor(L.)Moench)is one of the first cereal crops to be cultivated and domesticated.It has many characteristics such as drought resistance,flood resistance and salt and alkali resistance.It occupies an important position in dry farming and is also an important food crop.At the same time,sorghum has high utilization value and is an important raw material for the liquor brewing industry.At present,the main researches and development directions of brewing sorghum include the selection and breeding of new varieties,the analysis of the physical and chemical properties of grains,and the researches on the technical parameters of liquor brewing.However,the research on the grain quality,starch physical and chemical properties,and grain cooking quality are relatively independent,and there are few comprehensive reports on the impact of environmental and ecological factors in the pits on the quality of sorghum liquor during the fermentation process.Therefore,two waxy varieties[Jin Nuo 3(JN-3),Ji Niang 2(JN-2)]and four non–waxy varieties[Jia Xian sorghum(JX),Ji Za 127(JZ-127),Jin Za 34(JZ-34),Liao Za 19(LZ-19)]sorghum varieties were used as experimental materials to comprehensively analyze the agronomic characteristics,yield performances,grain quality,starch physical and chemical properties,grain cooking quality and fermentation of different sorghum varieties.The main conclusions of the study are as follows:(1)There were significant differences in agronomic traits,yield performances and grain quality among different sorghum varieties,which were mainly determined by the genotypes.The results showed that the excellent performance in the agronomic,yield and grain quality of the tested sorghum varieties was the non–waxy JX,which had a grain yield of 9842.92kg/hm~2,and the total starch was significantly higher than other varieties,and the protein content was significantly lower than other varieties.In addition,the fat and tannin contents were within the appropriate range,and JX was considered as more suitable liquor sorghum variety.(2)The water holding capacity,light transmittance,solubility and swelling power of waxy sorghum grain starch were higher than those of non–waxy sorghum.The six crystal structure types of sorghum starch were all type A.The absorption peak of waxy sorghum at a diffraction angle of 20.0°was weaker than that of non–waxy sorghum grain starch.The sorghum starch particle size ranged from 5 to 23?m.6 kinds of sorghum starch granules all showed typical"Maltese cross"by polarized light.and there were two clusters The P1 value of LZ-19(P1=66.5%)was the largest,which showed that the starch granules were larger and more complex;the P1 of waxy JN-3(P1=33.8%)The value was the smallest,the starch granules were smaller,the granules were simpler,and the distribution was scattered,but there was no significant difference between waxy and non–waxy rice.The starting temperature,ending temperature and enthalpy value of waxy sorghum grain starch slurry were higher than those of non–waxy,and there were significant differences between waxy and non–waxy sorghum,indicating that the starch structure of waxy sorghum grain was more compact and orderly than that of non–waxy sorghum.It was easier to gelatinize,and the required heat was higher.The gelatinization temperature,gelatinization time and valley viscosity of waxy sorghum starch were higher than those of non–waxy sorghum,and there were significant differences in the gelatinization retrogradation characteristics of waxy and non–waxy sorghum starch.(3)The water absorption and expansion rate of waxy sorghum after cooking and the reducing sugar content in the filtrate were all greater than those of non–waxy the results of the study showed that the grains of different sorghum varieties have been saccharified.The highest reducing sugar content in the filtrate was waxy JN-2,but the reducing sugar content of non–waxy JX was the second only to waxy JN-2,which was not significantly different from waxy JN-3.JN-3,JN-2 and JX three kinds of sorghum all showed easy gelatinization.The consistency and alkalinity of waxy sorghum gum were higher than those of non–waxy,and the iodine blue value was much lower than that of non–waxy.The results showed that the gelatinization temperature of waxy sorghum was lower.There were significant differences in the number of seed coat ruptures of waxy and non–waxy sorghum grains in different cooking periods,and the number of seed coat ruptures of waxy sorghum during the cooking process was less than that of non–waxy sorghum,which fully reflected the steaming resistance characteristics of waxy sorghum.(4)The temperature,moisture,acidity,starch and reducing sugar contents of the mash and the alcohol content of different sorghum varieties were basically the same.However,the acidity of the mash has remained stable after 15 days of fermentation,and the others continue to rise.In addition,fermentation 3 d,the change of reducing sugar content in JZ-127 and LZ-19 mash was opposite to the other four changes,which may be caused by the change of microbial population in the pit and environmental factors.There was no significant difference in the yield of waxy and non–waxy sorghum grains.The highest yield was the non–waxy JX,which reached 41.61%,followed by JN-3 and JN-2.The contents of ethyl acetate,ethyl caproate,ethyl butyrate,sec-butanol and isoamyl alcohol in non–waxy sorghum liquor was all higher than those in waxy.The results showed that the highest content of ethyl acetate and sec-butanol in the original liquor was the non–waxy JX,and the content of n-butanol and ethyl lactate was the least,and the ratio of ethyl acetate to ethyl caproate was also the most suitable.The content of n-propanol,isobutanol,sec-butanol and isoamyl alcohol in the waxy JN-2 original liquor was the lowest.In summary,there were significant differences in grain agronomic traits,yield performance,grain quality,starch physicochemical properties,cooking properties and brewing properties of different sorghum varieties,which ultimately led to different sorghum raw liquor with different aroma content,combined with the overall yield of different sorghum varieties.Analysis showed that under the same brewing process conditions of Fengxiang liquor,non–waxy JX was more in line with the characteristics of Xifeng liquor and was the main flavor characteristic of Fengxiang liquor.Waxy sorghum was rich in amylopectin,but it was easier to swell and gelatinize,and was more suitable for the brewing of sauce-flavor and luzhou-flavor liquor.