Effects of acidification on the extension of shelf life of Japanese wet-type noodles (woo-long noodle)

Noodles are one of the most important foods worldwide; various methods have been reported to extend their shelf life. In this study, the effects of dipping noodles in various concentrations of acidulant solutions (organic acids) on the shelf life of the noodles were evaluated. The results showed that the growth of the tested microorganisms, that is, Escherichia coli, Staphylococcus aureus and Bacillus cereus, was significantly inhibited when > 0.5% solutions of acidulants were applied. Here, a 0.5% mixed solution showed a larger halo zone diameter (8.5 to 11.5 nm) than 0.5% citric acid or 0.5% lactic acid solution (8.0 to 9.0 nm). Moreover, six variations of acidulants were used (0.5 and 1% citric acid, lactic acid and their combination), the shelf life at 5°C of the noodles dipped in a 0.5% 1:1 mixed solution for 20 s was also 4 to 6 days longer than those without treatment. All sensory attributes of noodles treated with the mixed solution were the highest (p<0.05) among all the samples. The results of the sensory study also indicated that products treated with the mixed solution had scores that were close to those of untreated noodles, in terms of appearance, texture, taste, hardness and elasticity as well as overall acceptance. Finally, these results provide support for developing a simple method to prolong the shelf-life of fresh noodles and minimizing any negative changes in sensory attributes. Key words: Acidity, organic acid, antimicrobial agents, microorganisms, sensory evaluation