Evaluation of nutrients, antioxidants and sensory characteristics of optimized wheat-orange-fleshed sweet potato and pumpkin composite bread and storage stability in three packaging materials

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This study evaluated the nutrients, antioxidants, physical and sensory properties of three optimized composite bread products formulated from wheat flour (WF), orange-fleshed sweet potato (OFSP) and pumpkin flour (PK). The optimized bread formulations were: WF-OFSP (70.6% WF and 29.4% OFSP, baked at 180 °C for 15 min); WF-PK (85% WF and 15% PK, baked at 180 °C for 20 min); and WF-OFSP-PK (78.5% WF, 11.5% OFSP, and 10.0% PK, baked at 160 °C for 20 min). Bread made from 100% wheat flour was used as control. Moreover, the study assessed the influence of three packaging materials, namely single-layer polyethylene (SLPE), low-density polyethylene (LDPE), and high-density polyethylene (HDPE) on bread quality and shelf life during storage at room temperature. The optimized composite bread exhibited significantly (p < 0.05) higher moisture, crude fibre, and ash contents but lower crude protein than the control bread. While carotenoids were not detected in the control bread, the levels in the composite bread ranged from 2.46 to 5.20 mg/100 g dry basis (d.b.). Moreover, total phenolic and flavonoid contents in the optimized composite bread were 3.0–4.8 folds and 4.3–7.2 folds higher, respectively, compared to the control. Additionally, the composite bread demonstrated superior DPPH radical scavenging activity and ferric-reducing antioxidant power than the control. The total carotene content of the optimized composite bread decreased by 19.6–31.5% during baking and 3.2–7.5% during storage. All packaging types used reduced moisture loss and improved total carotene stability in all bread samples compared with unpackaged bread, with no significant (p > 0.05) difference between packaging materials. The optimized composite bread had a microbial shelf life of 3 days. The composite bread had a higher preference for colour, aroma and sweetness but a lower preference for texture than the control. Nevertheless, the composite bread and control had comparable overall acceptability (liked very much). The production and consumption of these nutritionally and bioactive compounds riched composite bread products could help improve food security, nutrition and health.