Development Of Millet Fermented Beverage And Analysis Of Peptide And Fat Components Changes

Millet contains a variety of nutrients.Compared with other traditional grains,it has the same or higher content of protein,fatty acids,minerals,antioxidants and other nutrients.In this study,the fermentation process of lactic acid bacteria and yeast isolated from sour congee was used to explore the two-step fermentation process.A unique flavored fermented beverage was developed,and the changes of fatty acids,volatile substances and peptides were discussed and characterized.It provides a theoretical basis for the development and expansion of new millet fermented beverages.The lactic acid bacteria were screened by pH and sensory evaluation as indicators,and four strains of lactic acid bacteria were obtained,M1,M7,M10 and M14.Yeast was screened by alcohol content and sensory evaluation,and Y4 was obtained.The lactic acid bacteria and the yeast were rescreened in a ratio of 1:1,and it was finally determined that M10 and Y4 were the optimal fermentation strains.The method of simultaneous fermentation and two-step fermentation was compared.The results showed that the two-step fermentation method had high efficiency and good sensory evaluation,and the optimal fermentation process of lactic acid bacteria fermentation after yeast was obtained.According to the single factor experiment results of four factors of lactic acid bacteria:yeast inoculation ratio,yeast fermentation time,lactic acid bacteria fermentation time and fermentation temperature,orthogonal experiments were designed.The optimal fermentation conditions were as follows:fermentation temperature 34?,yeast fermentation time 24 h,yeast lactic acid bacteria composite fermentation time 24 h,inoculation ratio 2:1.The fatty acids of millet in different processing conditions were detected by gas chromatography-mass spectrometer.The experimental results show that short-time heating has little effect on fatty acid content,but due to the characteristics of the strain,the content of each fatty acid in the two-step fermentation has increased to varying degrees.The volatile compounds in the millet beverage were determined by SPME-GC-MS.The results of the experiment showed that after fermentation,the proportion of aldehydes decreased,and aromatic substances such as alcohols,esters and ketones were increased.Two-step fermentated millet beverage mainly detected 2-pentylfuran,ethanol,ethyl acetate,trans-2-nonenal and the like.The peptides in millet,millet stock and fermented millet milk were analyzed and compared by maldi-tof-ms.Five differential peptides between millet beverage before and after fermentation were determined by multivariate statistical analysis.It provides a new idea for the fermentation process to change the nutritional quality of the peptide.