Mold-free shelf-life extension of fresh rice noodles by synergistic effects of chitosan and common food preservatives

The antifungal synergy of chitosan (CH) was investigated with the common food preservatives, sodium benzoate (SB) or potassium sorbate (PS), against spoilage molds associated with fresh rice noodles to extend the shelf-life of the noodles and to reduce the use of chemical preservatives. To assess the synergistic effect of antimicrobial agents, we determined the fraction inhibitory concentration (FIC) index and isobolograms metric to justify the synergistic effect. We showed that CH with either SB or PS act synergistically against Aspergillus flavus and Penicillium citrinum. We also show that the combinations, 0.1% CH and 0.1% PS, completely inhibited molds and microbial growth of fresh rice noodles for longer than 28 days at the ambient storage condition. This longer storage time is a marked improvement from traditional noodles with either 0.1% added of PS or SB with a shelf-life of less than 1 day. Our combinations in fresh rice noodles show no effect compared to the control on the sensory evaluation and their physical properties including firmness, whiteness, and water activity. Thus, our research proposed the use of CH in combination with PS to extend the mold-free shelf-life of fresh rice noodles at 30 °C with no negative effects on noodle quality.