Rice noodle enriched with okara: Cooking property, texture, and in vitro starch digestibility

The effects of okara on in vitro starch digestibility and cooking properties of rice noodles and methods for quality improvement for their production as a functional health food were examined. Okara was added to rice noodles in proportions of 0%, 5%, 10%, and 20%. With an increasing level of okara, cooking loss, hardness, and adhesiveness of the rice noodles increased, while water absorption, swelling index, and cohesiveness decreased. The addition of okara reduced the in vitro starch digestibility of rice noodles, although the addition of 20% okara increased the starch digestibility. Among all samples, 10% okara showed the lowest predicted glycemic index (pGI) value. Therefore, in order to improve cooking quality of rice noodles containing 10% okara, addition of alginate or treatment with a CaCl2 coating was examined. The addition of alginate alone did not improve the cooking quality, but treatment with a CaCl2 coating along with alginate improved cooking quality. Moreover, the combination treatment of Ca-alginate did not change the in vitro starch digestibility of rice noodles containing okara. As a result, 10% okara can be used to produce health-beneficial rice noodles with reduced in vitro starch digestibility, and the combination treatment of Ca-alginate can improve their cooking quality.