A new strategy for the shelf life extension of fresh noodles by accurately targeting specific microbial species

Fresh noodles are subjected to rapid spoilage, mainly due to the microorganism, which adversely affect their shelf life. In this study, we developed a new specific strategy by targeting microbial species to extend the shelf life of fresh noodles. We found that at 4 °C, 15 °C, 25 °C and 37 °C, the shelf life of fresh noodles were 5, 1, <1 and < 1 days based on total viable count (TVC) and molds, respectively. The microflora in fresh noodles evolved from Acinetobacter and Pseudomonas (4 °C) to Pantoea, Bacillus, Staphylococcus, and Lactobacillus (15 °C), then to Bacillus, Pantoea, Staphylococcus and Lactobacillus (25 °C), and finally to Bacillus, Staphylococcus, Lactobacillus and Pantoea (37 °C) at genus level proved by high-throughput sequencing. Total forty-five microbial species at different temperatures were isolated and identified, fourteen of which were picked out to screen food preservatives. E. faecalis was the hardest bacteria for protamine to be inhibited in the fresh noodles. The combination of 0.1% glycerol monooctanoate (GMC) +0.1% protamine extended the shelf life of fresh noodles from 1d to 3d at 25 °C and from 7d to 28d at 4 °C. P. agglomerans and E. faecalis, E. faecium and E. durans were responsible for deterioration of the fresh noodles at 4 °C and at 25 °C, respectively. Additionally, MIC test showed the chitosan lactate had anti-bacteria abilities towards both E. faecalis and P. agglomerans. The results showed that the combination of chitosan lactates + protamine + GMC increased the shelf life of the fresh noodles from 1d to 4d at 25 °C due to the synergistic inhibition of P. agglomerans and E. faecalis. It was the first time aiming at specific target strains to develop new preservatives. With this new approach, the storage accuracy and efficiency of fresh noodles can be improved.