Characterization of Microorganisms in Producing Natural Fermented Rice Noodles

摘要

The evolution of microbial floras in producing natural fermented rice noodles was investigated in this study. The microbial varieties were isolated and screened on the basis of morphological properties of colonies grew on the selective media and their fermentation effects on the rheological properties as well as eating qualities. The results revealed that the microorganisms mainly come from the rice granules with initial bacterial count up to 5 log cfu/mL. The natural fermentation was an anaerobic process, and the anaerobic plate count reached its maximal value of 10.21 log cfu/mL after 72 h of fermentation. LAB was the dominant microorganism, up to as high as 10.63 log cfu/mL. The second dominant microorganisms were yeasts, about 4-5 log cfu/mL. By further isolation and screening, five bacteria, two LAB and three yeasts were obtained. Rheometer measurements indicated that the larger quantity of acid yielded by the microorganisms produced more significant effects on the improvement of rheological properties. Therefore, natural fermentation process for producing the rice noodles is actually a lactic acid fermentation one. LAB plays a key role in improving the physical properties and eating qualities of rice noodles.