Abstract: In this study we compared the influences of fermentation by pure cultures of two strains of lactic acid bacteria and two strains of yeast and natural fermentation on the quality of instant rice noodles. The results showed that the highest tensile stress, hardness, elasticity, cohesiveness, chewiness, resilience and water absorption rate and the lowest cooking loss were obtained after 36–48 h fermentation by Lactobacillus plantarum CSL23 among the four strains tested. By contrast, 48 h fermentation by L. fermentum CSL30 provided the second highest tensile stress, elasticity, cohesion, resilience, water absorption rate and cooking loss rate in instant rice noodles, but the lowest hardness, viscosity and chewiness. Instant rice noodles produced by 60 h natural fermentation displayed better tensile stress, hardness and chewiness with texture characteristics and cooking properties being at a middle level. Instant rice noodles obtained by S. cerevisiae CSY13 fermentation had distinct flavor characteristics with higher viscosity and lower cohesion. The effect of T. asahii CSY07 fermentation on the tensile stress, texture characteristics and cooking properties of instant rice noodles was inferior to that of natural fermentation, but it had the second largest effect on the flavor after S. cerevisiae CSY13. In short, lactic acid bacteria is conducive to the eating quality of instant rice noodles, whereas yeast is beneficial for the flavor; the quality of instant rice noodles can be assured by pure culture fermentation in a shorter time.

Key words: lactic acid bacteria, yeast, fermentation, instant rice noodles, quality