Isolation, Identification and Antibacterial Screening of Spoilage Organism in Guilin Rice Noodles

Guilin rice noodles belong to fresh wet rice noodles, which are difficult to be preserved due to their high moisture content and susceptibility to microbial contamination. Therefore, it is very important to analyze its putrefactive bacteria and screen bacteriostatic agents for extending the shelf life, and maintain the taste and nutritional value. In order to study the microbial growth during the storage of Guilin rice noodles, 13 strains of spoilage organism were isolated and purified from Guilin rice noodles stored at room temperature for 1 to 3 days, and six main spoilage organism MF1, MF2, MF3, MF4, MF6 and MF12 were obtained through the counterfactual experiment. Then the main spoilage organism were identified as Bacillus thuringiensis, B. cereus, B. velezensis, Citrobacter sp. and Exiguobacterium acetylicum through routine identification combined with molecular identification. Furthermore, the effective antibacterial agents and optimal inhibitory concentrations were selected from five food additives through the plate culture. The results showed that different concentrations of ascorbic acid and citric acid had good antibacterial effects on six types of spoilage bacteria, with the optimal inhibitory concentrations being 90 and 120 mg/mL, respectively. This shows that ascorbic acid and citric acid can be used as preservatives of Guilin rice noodles and have a certain application prospect in the storage and fresh-keeping of Guilin rice noodles.