Optimization of Sweet Potato Flour and Black Cumin Seed Blending Ratios with Wheat Flour to Produce Quality Bread

This study aimed to optimize the proportion of black cumin and sweet potato flour and its effect on physicochemical qualities and sensory acceptability for bread development. The three level of concentration ratios of black cumin obtained from the baseline survey of data are black cumin(B1), 1.09g, black cumin (B2) = 2.29 g, and black cumin (B3) = 3.49 g). A total of 13 formulations were analyzed with sweet potato flour ranging from 8 to 22 gram and black cumin seed ranging from 0.59 to 3.89 gram. A response surface methodology (RSM) coupled with Central Composite Rotatable Design (CCRD) was employed to design and optimize the varying levels of sweet potato flour and black cumin seed. The responses analyzed included carbohydrate content, protein content, and sensory acceptability. The sensory attributes were significantly affected by the blend proportion of sweet potato flour and black cumin (p < 0.05). The experimental results showed that increasing black cumin levels improved protein content and sensory attributes up to an optimal point, while excessive amounts slightly reduced carbohydrate levels. The predicted and experimental values were compared and showed no significant differences at p < 0.05. Hence, the developed models were found adequate and had good predicting capacity. The models’ prediction values have no significant difference with the measured confirmation values (with minimal deviation). Results indicated that increasing sweet potato blend levels generally enhanced carbohydrate content at 85.03%. In contrast, protein content was positively influenced by higher black cumin levels, with the highest measured value of 8.0%. Sensory scores were highest (4.75) at a mid-range formulation of black cumin and sweet potato, suggesting a favorable over all acceptability. The optimal formulation was determined to consist of 11.8 g of sweet potato and 3.49 g of black cumin, achieving a desirable nutritional profile with 82.22% carbohydrates, 7.9% protein, and a high sensory score of 4.41 reflecting strong consumer preference. In terms of mineral content, it was notably rich in calcium, iron and zinc. These predicted blending ratios of sweet potato flour and black cumin could help to formulate bread production with acceptable energy, nutritional qualities and sensorial acceptance.