| Sorghum bicolor(L.)Moench is widely grown in the arid and semi-arid regions of China and has received much attention due to its excellent drought tolerance and its recognition as a nutritious food.Sorghum is used for food and feed,as well as for brewing liquor,and is also a suitable crop for sustainable intercropping.Because of these values,sorghum research is of great importance.However,the nutritional values and functional properties of sorghum grains(flour and starch),are not well understood.Therefore,research on the nutritional quality and physicochemical properties of sorghum seeds is important to promote the sorghum industry.Six varieties of sorghum,namely,Jinza 34(JZ-34),Liaoza 19(LZ-19),Jinnuo 3(JN-3),Jiza 127(JZ-127),Jiniang 2(JN-2),and Jiaxian(JX)were selected for this study to systematically investigate the relationship between nutritional quality and functional properties of sorghum seeds,analyze the physicochemical properties of sorghum starch,evaluate the fermentation quality of different sorghum varieties,and explore fermentation characteristics of sorghum and to lay the foundation for the industrial development and application of sorghum.1.Six sorghum grain nutritional quality characteristics were analyzed.The results indicated that LZ-19 had the highest bulk density(BD),tapped density(TPD),and true density(TD),while JZ-34 had higher porosity(P)compared to other varieties.JZ-34 flour had the highest Carr‘s index(CI)and angle of repose(AR)and displayed good fluidity and compressibility in terms of micron properties.JN-3 and JX had the highest protein and fat content as determined by approximate analysis,and their contribution to total energy value was significantly different.Scatterplot analysis revealed a strong positive correlation between the proportion of energy contribution and protein,fat,and carbohydrate.JZ-127 had the highest amylose content,while the lowest values were observed in JN-3 and JN-2.JN-3had the highest mineral content and anti-nutrient contents,including flavonoid and total phenols.Based on amino acids(AAs)composition,JN-3 was found to have potential as a dietary supplement in commercial food applications.JN-2 sorghum showed the highest light transmittance(LT),water absorption capacity(WAC),oil absorption capacity(OAC),and least gelation concentration(LGC)in functional property determinations.JX and JZ-127 had the highest water solubility(WS)and swelling capacity.In heat map correlation analysis,LT had high positive correlation with WAC(r = 0.909)and OAC(r = 0.909).AM content had a high negative correlation with LT(r =-0.873),WAC(r =-0.817),and OAC(r =-0.817),but a positive correlatin with water solubility(r = 0.714)and swelling power(r = 0.824).These results suggest that JN-3,with its combination of nutrients and functional properties,is an ideal candidate for use in brewing liquor.2.From the perspective of the physicochemical properties,JZ-127 having the highest amylose content.Scanning electron microscopy(SEM)and polarized light microscopy(PLM)showed that the starch granules were all regular polygonal round shapes and had a―Maltese cross‖ shape,respectively.Flow cytometry analysis showed that the granules of LZ-19 were larger and more complex,followed by JN-2.X-ray diffraction analysis revealed that all sorghum starches had a ―Type-A‖ diffraction pattern,with JZ-34 having the highest relative crystallinity(RC)and JN-3 having the lowest.JN-3 and JN-2 with low amylose content showed higher LT and WHC.JZ-34 starch had high peak and breakdown viscosity,as well as low trough viscosity.JN-3 showed higher onset temperature,peak temperature,conclusion temperature,gelatinization enthalpy,and gelatinization range compared to other treatments.Principal component analysis showed that the properties of JN-2 and JN-3 were similar and strongly negatively correlated with other starches.Hierarchical cluster analysis revealed that cluster(I),including LZ-19,JZ-34,JX,and JZ 127,had a high association with amylose content,water solubility,peak viscosity,BD viscosity,final viscosity,and setback viscosity.Cluster(II),consisting of JN-2 and JN-3,had higher swelling power,thermal properties,and were associated with TV,PT,and PTM.These results indicate that all selected sorghum varieties play an important role in developing industrial processes.3.The analysis of the relationship between liquor flavor and the physicochemical properties and microbial diversity of the fermented grains shows that ethyl acetate was the main flavor component in JZ-127,JZ-34,and JX,while ethyl lactate was mainly found in JN-2,JN-3,and LZ-19.Ethyl lactate accounted for half of the ethyl acetate content,and the liquor yield of JX was higher than that of other sorghum varieties.The temperature and reducing sugar content in the fermented grains of waxy sorghum was high,with low moisture and starch content.JN-3 and JX were selected for further research to explore changes in microbial biodiversity in fermented grains.Bacterial diversity gradually decreased,while the fungal diversity in JN-3 and JX showed no progression.Lactobacillus was the most abundant bacterial genus and its content increased rapidly during fermentation,with a higher abundance in JX compared to JN-3.Yeast was the most abundant fungal genus in JX,but its abundance was low in JN-3.Four esters and five alcohols were positively correlated with Proteobacteria,Bacteroidetes,and Actinobacteria;Alphaproteobacteria,Actinobacteria,and Bacteroidia;Bacillales,Bacteroidales,and Rhodospirillales;and Acetobacter,Pediococcus,and Prevotella＿7.This positive relation is in contrast with that observed for Firmicutes,Bacilli,Lactobacillales,and Lactobacillus.Meanwhile,Aspergillus was the only fungal microorganism that showed a significantly negative relation with such compounds(except for butanol and isopentanol).These findings will help in understanding the fermentation mechanism and flavour formation of fermented Xifeng liquor.In summary,different genotypes of sorghum showed differences in proximate composition,energy value contribution,amino acid composition and functional composition.Moreover,the structure and physicochemical properties of starch significantly influenced the fermentation characteristics.Analysis showed that under the same brewing process conditions,JX was the main flavor characteristic and JN-3 was rich in amylopectin,but it was easier to swell and gelatinize,and were more suitable for the brewing of sauce and strong flavor of Xifeng liquor.These results contribute to the future use of sorghum starch in food and non-food industries and offer a wealth of microbial diversity resources for the production of fermented Xifeng liquor. |
PDF Full Text Request