Flavor Change During Mixed Fermentation Of Broken Rice And Germinated Brown Rice And Optimization Of Its Technological Conditions And Quality

This study uses broken rice and germinated brown rice as raw materials.By inoculating Aspergillus oryzae and Bifidobacteria,using a secondary fermentation process,the evolution of volatile flavor compounds and the effects of soybean oligosaccharides on fermentation quality were investigated.At the same time,the influence of the process conditions of extrusion on the quality is discussed.And comparative analysis of the quality of different processing methods,and evaluated by in vitro simulated digestion.The main findings of this paper are as follows:1.Volatile flavor test results show that: The effects of fermentation time on nitrogen oxides,methane,alcohols and aldehydes and ketones were significantly different(p<0.05).Adding Bifidobacterium longum and soybean oligosaccharide solution for secondary fermentation compared to one fermentation sample There are differences in the first and second principal components of volatile matter components.This indicates that secondary fermentation contributes a lot to flavor components.The volatile flavor components of fermented rice and baking powder are mainly esters,alcohols,phenols and other compounds.The type and content of the secondary fermentation process increased.In the secondary fermentation,volatile constituent substances such as ethyl oleate,ethyl undecanoate,4-vinyl-2-methoxyphenol,2-n-pentylfuran,and 2-fluorenone were detected.2.The experimental results of the extrusion process optimization show that:When the water content of the twin-screw extruded material is 10% to 15%,the expansion temperature in the II zone is 115°C to 125°C,and the broken particle size is 26 to 60 mesh.The obtained product has the highest sensory evaluation score and the best preparation.3.Comparative analysis of the quality of different processing methods for rice products shows that: There were significant differences in WAI/WSI values of rice products with different processing methods(p<0.05).And the water absorption index and water solubility index of the extruded rice products arehigher than the flat dry rice products.The steady state rheological test results show that: The viscosity coefficient of rice products with different processing methods decreases with the increase of shear rate;Flat dry fermented rice products increase with frequency,the shear stress first increases and then decreases.The results of electronic nose test showed that different processing methods had significant effects on aromatic components,methane,alcohols and aldehydes and ketones(p<0.05).4.Simulated gastrointestinal fluid digestion test results show that: The order of release of polyphenols and flavonoids in the four rice products is as follows:Gastric digestion group > HCl control group > blank control group,intestinal digestion group > blank control group.The release of polyphenols and flavonoids in rice products showed a significant upward trend(p<0.05).The maximum release of polyphenols and flavonoids in the gastric digestive and intestinal digestive groups were all mixed powder fermentation flat drying processes.