Nutritional, Functional, and Microbial Quality of Wheat Biscuits Enriched With Malted Pearl Millet and Orange Peel Flours

Abstract

In this study, composite biscuits were produced by combining wheat flour (WF) with different proportions of malted pearl millet (MPM) flour (8%, 16%, 24%, and 32%) and orange peel (OP) flour (2%, 4%, 6%, and 8%), using 100% WF as a control. The investigation covered the functional properties, viscosity, and thermal properties of the flours, along with the proximate composition, antioxidant, physical properties, color attributes, and microbial quality of the composite biscuits. As MPM and OP flour (OPF) contents increased, water absorption capacity, dispersibility, and foaming power increased, while the viscosities of both hot and cold pastes decreased. The thermal properties of the composite flours, including onset, peak, and final temperatures (ranging between 74.19°C and 100.76°C), showed an upward trend with increasing proportions of MPM and orange peel flour (OPF). There was an increase in moisture content (3.43%–4.93%), ash (4.50%–5.59%), crude protein (11.70%–13.41%), and crude fiber (11.44%–16.24%) of biscuits with the incorporation of MPM and OPF. Similarly, the diameter (4.12–4.60 mm), thickness (9.00–10.00 mm), and hardness (7.53–8.75 N) of the biscuits were increased. Antioxidant properties were evident, with an increased total phenolic content (1.40–3.56 mg GAE/100 g), total flavonoid content (2.91–6.79 mg QUE/100 g), vitamin C (0.79–1.01 mg/g), and ferric reducing antioxidant power (1.78–8.64 mg GAE/g). Conversely, color attributes—L* (31.90), a* (10.82), b* (19.59), hue angle (30.42), and chroma (53.66)—were found to decrease with higher levels of MPM and OPF. Microbial quality showed decreased total counts, coliforms, yeasts, and mold in biscuits containing MPM and OPF. Overall, the inclusion of MPM and OPF enhanced the nutritional quality of the biscuits and could reduce reliance on imported wheat.