Physicochemical and Sensory Evaluation of Biscuits Produced from Composite Flour of Wheat and Fermented Cowpea Hull

Aims: This study investigated the physicochemical and sensory properties of biscuits made from a composite flour of wheat and fermented cowpea hull.

Study Design: Mixture Design was adopted for this study.

Place and Duration of Study: Department of Food Science and Technology, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria, between January 2023 and March, 2024.

Methodology: Cowpea hulls were cleaned, soaked, boiled, dehulled, and fermented with Rhizopus oligosporus for 48 hours. The resulting hulls were dried, milled, and blended with wheat flour in varying ratios (95:5, 90:10, 85:15, 80:20, 75:25, and a 100% wheat control). The composite flours were then used to produce biscuits, which underwent proximate, physical, and sensory evaluations using a 9-point hedonic scale.

Results: Results showed that the inclusion of fermented cowpea hull significantly increased moisture (9.75-11.55%), ash (1.59-2.85%), crude protein (10.75 - 12.05%), fat (0.96 - 1.95%), and crude fibre (4.55 - 5.30%) content, while carbohydrate content decreased (72.37-66.31%). Physically, the biscuits exhibited an increase in thickness (4.40 - 5.55 mm) and weight (9.64 - 11.85g), but a decrease in height (4.85 -3.90 cm) and breaking strength (3.70 - 2.65). Sensory evaluations indicated that higher levels of fermented cowpea hull negatively impacted the biscuits' quality in terms of colour (7.25 - 6.15), taste (7.45 - 6.25), aroma (7.15 - 6.75), flavour (7.60 - 6.40), and overall acceptability (7.50 - 6.60). The biscuit with 5% fermented cowpea hull was the most acceptable (7.05), after the control sample made with 100% wheat (7.50).

Conclusion: This study demonstrates that nutritionally enhanced biscuits can be produced using a blend of wheat and fermented cowpea hull, though the inclusion should not exceed 10% as to maintain high sensory acceptability.