Study On Properties Of Fermented Rice Flour And Starch

In order to explore modified mechanism of fermented rice noodles, the characteristics of rice fermentation and eating quality of rice noodles which effected by the main microorganisms were studied. The microbial which had the best modification result was selected for rice fermentation and then starch was extracted from rice flour using protease protein removal method. The physicochemical properties of rice flour and starch during fermentation were studied in this paper. The cooking and textural properties of fermented rice noodles were also investigated. The main results were concluded as follows.Total acid, total solids, protein content in broth increased while pH decreased gradually during fermentation. Protein and ash content in the rice flour decreased while starch content and brightness increased gradually during fermentation, in which Lactobacillus plantarum had a remarkable influence. The results of sensory evaluation showed that the fermented rice noodles became more flexibility and chewiness, in which Lactobacillus plantarum had a better modified.With fermentation, the average particle size of rice flour granules decreased and the proportion of small granules increased. Intrinsic viscosity of starch decreased with prolonged fermentation time. Fermentation did not affect the polarization cross of starch granules. FTIR and XRD analysis results indicated that fermentation would not destroy functional groups of starch, but the crystalline region proportion of starch had a slight increase by fermentation.The changes of pasting and gel properties of rice flour and starch during fermentation were studied. The fermented starch had a low transparency and a large retrogradation. The pasting temperature, peak time and setback of fermented rice flour decreased, while the peak viscosity and breakdown increased. The fermentation time had little influence on the pasting temperature and peak time of rice flour, but the peak viscosity and breakdown firstly increased and then decreased with fermentation time extending. Meanwhile, the pasting temperature, peak viscosity, breakdown and setback of fermented rice starch decreased, but the peak time increased. The effect of fermentation time on the gelatinization temperature, peak viscosity of starch was less than that on breakdown and setback. The hardness, adhesiveness, gumminess and chewiness of gel of rice flour and starch increased after fermentation, but there existed no obvious changes with extending fermentation time.The cooking and textural properties of fermented rice noodles and the relevance with physicochemical properties of rice flour and isolated starch were studied. The cooking and texture of fermented rice noodles were substantially affected by fermentation. The hardness, gumminess, chewiness, elasticity, tensile force and tensile distance of fermented rice noodles increased, with smaller cooking loss and more rehydration. During the rice fermention, starch structure changed, the average particle size of rice flour became smaller, protein and fat content of rice flour decreased, but amylose content increased and all of that were the main reasons for the changing of fermented rice noodles.