Orange-fleshed sweet potato (OFSP) flour is rich in health-promoting compounds that can improve the nutritional benefits of baked products when blended with wheat flour. However, the flour particle size and blend proportion may affect the quality properties and consumer acceptability of bakery products. This study investigated the effect of flour particle sizes and blend proportions on the physical, nutritional, textural and sensory properties of peeled and unpeeled OFSP composite flour cookies. Peeled and unpeeled OFSP flours (≤ 250 μm and ≤ 500 μm particle size) were produced, and each was used to replace soft wheat flour at the rate of 0 to 100% for cookies formulation. The results obtained showed that substitution of wheat flour with OFSP flours significantly (p < 0.05) decreased cookies baking loss, thickness, volume, crust lightness (L*) but increased diameter, spread ratio, crust redness, yellowness, contents of ß-carotene, vitamin A, ascorbic acid, total phenolics and flavonoids, and the antioxidant capacity. The hardness and fracturability of the OFSP-based cookies ranged between 1.389 and 10.142 kg and 0.873 and 9.431 kg, respectively, whereas the values of the control cookies were 1.281 ± 0.003 kg and 1.274 ± 0.003 kg, respectively. The effect of flour particle size on the physical and nutritional properties of cookies was insignificant (p > 0.05). However, the ≤ 250 μm particle size flour cookies had higher overall acceptability than the ≤ 500 μm particle size flour cookies. The unpeeled OFSP composite cookies had higher bioactive compounds concentrations except for ascorbic acid but had lower overall acceptability than the peeled OFSP cookies. Generally, the 30% peeled OFSP composite flour cookies had the highest consumer acceptability.

Orange fleshed sweet potato (OFSP) has great potentials to improve the nutritional benefits of bakery products when processed into quality flour. This study investigated the effects of sieve particle sizes (250 μm and 500 μm) and flour blend proportions on the physicochemical, nutritional, functional and pasting properties of peeled and unpeeled OFSP composite flours. Peeled OFSP composite flours had significantly (p < 0.05) higher crude protein (CP), lightness (L*), oil absorption capacity (OAC) and water solubility (WS) but lower crude fiber (CF), bioactive compounds (except ascorbic acid), water absorption capacity (WAC) and swelling capacity (SC) than the unpeeled OFSP composite flours. The sieve particle size had no significant (p > 0.05) effect on nutritional and pasting properties. However, OFSP-based flours sieved with 500 μm mesh particle size had a significantly (p < 0.05) higher WAC and SC but a lower WS than corresponding 250 μm mesh flours. The proportions of flour blends greatly (p < 0.001) influenced all quality properties of OFSP composite flours. Generally, OFSP composite flours had higher CF, bioactive compounds, WAC, SC and WS, but lower CP, fat, OAC and pasting properties than wheat flour. The quality properties indicated that peeled and unpeeled OFSP flours sieved with a 250 μm or 500 μm mesh size have great potentials as ingredients in the bakery industry.

The shea fruit pulp (SFP), a by-product generated during the processing of shea fruit, is a vital source of phytochemicals for the development of functional foods. This study determined the effect of partial substitution of wheat flour with SFP (0–25%) on the physicochemical, total carotenoids (TC), total phenolics content (TPC), antioxidant activity (AA), and sensory properties of cookies. The bromatological analysis showed that crude fiber, fat, and total ash contents of the SFP-enriched cookies increased by 155.3-565.8%, 1.7–6.8%, and 22.2-111.3%, respectively while moisture, crude protein, and available carbohydrate contents decreased by 10.0-44.9%, 3.1–17.5%, and 1.0-2.9%, respectively with increasing addition of SFP in the cookies. The SFP-enriched cookies had significantly higher TC (183.25-627.49 µg/100 g) and TPC (79.06–185.20 mg GAE/100 g) and AA (28.20-61.58%, inhibition) than the 100% wheat flour cookies, control (2.90 ± 0.14 µg/100 g for TC, 53.81 ± 5.70 mg GAE/100 g for TPC, and 15.79 ± 1.03% for AA). The incorporation of SFP in cookies decreases the thickness and whiteness index by 3.9–24.0% and 4.5–26.9%, respectively, but increases the spread ratio by 5.5–37.9% and the browning index by 10.3–87.4% as compared with the control cookies. Based on the sensory evaluation results, the 25% SFP-enriched cookie had the highest scores for taste, aroma, and texture whiles the 15% SFP-enriched cookie had the best rating for color and overall acceptability. It is conclusive that SFP could be utilized for the industrial production of cookies to enhance the nutritional, antioxidant, and sensory properties of the baked product. Nonetheless, enzymatic browning of the shea fruit pulp is a major limitation, and therefore, rapid processing of fruits and cold storage of the SFP is required to prevent the browning reactions of the SFP. Graphical Abstract