Plant based protein products: Characterization and functionality of dried tofu noodles containing lotus root powder

Abstract

The current study investigated the effect of replacing wheat flour with starchy root vegetables in dried tofu noodles on texture, color, antioxidant capacity, and starch digestibility. The lotus root was selected as a replacement for wheat flour (5%, 10%) based on antioxidant capacity among various starchy root vegetables such as smilax china, lotus root, taro, and yam. Dried tofu noodles added 5% (W65L5T30) and 10% (W60L10T30) lotus root powder did not show any difference in springiness, but their hardness decreased compared to control (W70T30) after cooking. Changes in lightness (ΔL*) increased while its yellowness (Δb*) decreased according to the added amount of lotus root powder due to the oxidation of phenolic components by polyphenol oxidase. However, the antioxidant capacity expressed as trolox equivalent (TE, μmol TE /g dw) was maintained after cooking. In the enzymatic starch hydrolysis, the lowest amount (11.21 ± 1.25%) of rapidly digestible starch (RDS) and the highest amount (57.80 ± 3.13%) of resistant starch (RS) were observed in W60L10T30. After gelatinizing for 20 min, the content of free glucose was 3.56, 3.39, and 3.17% for W70T30, W65L5T30, and W60L10T30, respectively. Results from the current study suggest that lotus root powder as a replacement for wheat flour in dried tofu noodles could be effective not only in improving texture and antioxidant capacity but also in delaying starch digestion after cooking. Lotus root powder could be a potential ingredient that can replace wheat starch in dried tofu noodles as a low glycemic index food, meal replacement for diabetes.