Quality Evaluation of Biscuits Produced from Wheat, Tigernut Residue and Rice Bran Flour Blends

Abstract

Biscuits are baked snack products made mainly from flour, fat, and other ingredients such as sugar and leavening agents. Wheat flour is the principal ingredient in most biscuits; however, increasing demand for healthier and sustainable foods has encouraged the use of alternative ingredients such as tigernut residue and rice bran due to their nutritional and functional benefits. This study evaluated the quality of biscuits from wheat, tigernut residue, and rice bran flour blends with the aim of developing a nutritionally enriched and environmentally sustainable bakery product. Five flour formulations were prepared by substituting wheat flour with varying proportions of tigernut residue and rice bran (0–25%), designated as samples A (100% wheat flour which served as control), B (90:5:5), C (85:10:5), D (80:15:5), and E (75:20:5). The functional properties of the composite flours, as well as the proximate composition, physical characteristics, and sensory attributes of the biscuits, were evaluated using standard analytical methods. Results showed that water and oil absorption capacities, as well as swelling capacity, increased significantly (p < 0.05) with higher substitution levels, while bulk density and foaming capacity decreased. Proximate analysis revealed a progressive increase in fibre (1.49–4.86%), ash (1.18–1.61%), and protein (7.46–7.95%) contents with increasing substitution, whereas carbohydrate content decreased (65.36–59.77%). Physical evaluation indicated slight increases in biscuit weight and thickness, accompanied by reductions in diameter and spread ratio. Sensory results revealed that appearance, taste, crispiness, and overall acceptability declined with increasing substitution levels, but biscuits with up to 15% composite inclusion (sample D) remained generally acceptable to panelists. The findings demonstrate that partial substitution of wheat flour with tigernut residue and rice bran can produce nutritionally superior biscuits rich in dietary fibre, minerals, and protein without severely compromising sensory quality. Moreover, the study underscores the potential of utilizing tigernut residue and rice bran, materials often treated as agro-waste, as valuable food ingredients, thereby promoting waste minimization, value addition, and environmental sustainability. Therefore, a substitution level of 10–15% is recommended for the formulation of acceptable and functional biscuits that support both nutritional enhancement and eco-friendly food production initiatives.