This study aimed to evaluate the use of okara, a soybean by-product, as a food ingredient by formulating nutrition bars fortified with okara and to analyze their physicochemical characteristics, antioxidant components, and antioxidant activities. The moisture content of okara-added nutrition bars (ONBs) ranged from 36.06 to 38.59%. The ash content ranged from 1.40 to 2.01%, showing a significant upward trend with increase in amount of okara (p<0.05). The pH values of the ONBs ranged from 6.87 to 7.11, showing a significant decrease with increase in okara content, whereas titratable acidity showed the opposite trend (p<0.05). Total content of soluble solids ranged from 3.2 to 3.7 °Brix, and a significant increase was observed in the ONBs with added okara compared to the ONBs without added okara. The lightness (L*), redness (a*), and yellowness (b*) of the color values of the nutrition bar samples did not show any significant changes with the addition of okara. No significant differences were observed in the color parameters. The browning intensity increased significantly with increasing okara content (p<0.05). The total polyphenol and total flavonoid contents of the nutrition bar increased significantly in a concentration-dependent manner with the addition of okara (p<0.05). The antioxidant activity assays demonstrated that 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities, ferric reducing antioxidant power (FRAP), and reducing power all increased significantly with increase in okara content (p<0.05). Further studies are required to evaluate consumer acceptability, determine the optimal concentration of nutrition bars, and assess consumer purchase intention for the developed products.
Jang et al. (Thu,) studied this question.