Effects of thermal treatment on the microbial shelf-life and quality stability of wet instant cooked noodles during storage

Abstract

Pasteurization, acidification followed by pasteurization, and autoclave extended the shelf-life of cooked noodles (groups S1, S2 and S3) to 3, 180 and 180 days, respectively. Pasteurization increased the hardness of cooked noodles from 53.60 to 58.01 N. However, the growth of thermoduric bacteria caused a decrease in pH, coloration, and hardness of group S1 during storage. Meanwhile, the pH and hardness of group S2 decreased to 4.42 and 39.22 N respectively, while hardness and chewiness increased during storage. In addition, physicochemical-textural characteristics of group S3 are maintained throughout storage. The hardness of groups S1 and S2 is related to the gluten structure. The compact gluten network formed after pasteurization. Meanwhile, acidification inhibited the polymerization of glutenin and gliadin. The starch melted after autoclave, masking the impact of the gluten network and decreasing hardness. During storage, hydrolysis of protein and starch by bacteria resulted in the deterioration of group S1. Recrystallization of starch resulted in the stiffening of group S2. The absence of metabolism of bacteria and presence of stable gluten in group S3 contributed to the stable starch structures, inducing its stable quality. Thermal treatment can be recommended as an effective additional treatment for producing shelf-stable wet instant cooked noodles.