This study was conducted to develop an upcycled vegan ragù sauce with enhanced functionality and added value by utilizing okara, a low-value by-product generated in large quantities by the food industry, through fermentation, and to scientifically el...
This study was conducted to develop an upcycled vegan ragù sauce with enhanced functionality and added value by utilizing okara, a low-value by-product generated in large quantities by the food industry, through fermentation, and to scientifically elucidate its quality characteristics and functional properties.
The reutilization of by-products generated during soybean processing has been recognized as a critical challenge for achieving sustainability in the food industry. Accordingly, the primary objective of this study was to optimize the manufacturing process of a vegan ragù sauce incorporating fermented okara, verify its potential as an alternative to conventional meat-based sauces, and evaluate its functional improvements, including antioxidant and anti-diabetic activities.
Response Surface Methodology (RSM) was applied in this study, with fermented okara, tomato purée, and long beans set as independent variables to determine the optimal mixing ratio for sensory and physicochemical quality. In addition, okara fermented for different durations (0, 12, 24, 36, and 48 h) was applied to vegan patties to evaluate sensory characteristics, while general compositional analysis and functional properties—including total polyphenol content, DPPH radical scavenging activity, and α-glucosidase inhibitory activity—were assessed according to fermentation time.
Sensory evaluation revealed that the 36-hour fermentation group received the highest scores for color, taste, texture, and overall preference, confirming 36 h as the optimal fermentation time for okara (p < 0.001). Physicochemical analyses demonstrated that increasing the proportion of fermented okara resulted in significant changes in pH, salinity, sweetness, and color values (L, a, b). These changes were attributed to texture modification induced by Maillard reactions occurring during fermentation, accompanied by decreases in salinity and lightness (L) and increases in umami intensity, redness (a), and yellowness (b), consistent with previous findings (Zheng Z. et al., 2023). Furthermore, total polyphenol content and DPPH radical scavenging activity increased significantly with prolonged fermentation (p < 0.0001), and α-glucosidase inhibitory activity reached its maximum value (60.32%) in the 36-hour fermentation group, indicating enhanced antioxidant and blood glucose–lowering effects.
Proximate composition analysis showed that the 36-hour fermented ragù sauce exhibited the highest protein content (16.09%), while fat content and caloric value were reduced. These findings suggest that fermented okara ragù sauce has strong potential as a health-oriented alternative food characterized by low fat, low calories, and high protein content compared to conventional meat-based sauces.
Numerical optimization using canonical analysis yielded a high desirability value of 0.863, with the optimal formulation determined as fermented okara 92.534, tomato purée 97.033, and long beans 19.017. Predicted sensory values were as follows: sweetness 4.729, flavor 4.260, sourness 4.516, color 4.287, viscosity 4.873, texture 4.263, and overall preference 5.234. Although certain volatile compounds derived from fermented okara (such as organic alcohols, ketones, and aldehydes) were perceived as off-flavors by some panelists, resulting in relatively lower flavor scores, the overall sensory quality was highly optimized.
In conclusion, this study demonstrates the feasibility of enhancing the utilization of okara, a low-value food by-product, and verifies its potential for sustainable food development and value-added product innovation. Moreover, by elucidating antioxidant and anti-diabetic activities through fermentation, the findings provide foundational data for future research on undervalued food resources and the development of high-nutrition, eco-friendly alternative protein foods through fermentation.