Micronutrient and Phytochemical Composition of Bread Produced from Black Bean Flour and Pigeon Pea Composite Flour

Abstract

This study investigated the micronutrient and phytochemical composition of black bean (Phaseolus vulgaris) flour and pigeon pea (Cajanus cajan) flour, as well as the quality attributes of bread produced from their composite flours. The study aimed to enhance the nutritional quality of bread by using processed black bean and pigeon pea flours as partial substitutes for wheat flour, while evaluating the influence of processing techniques on micronutrient retention, phytochemical composition, and overall bread quality. Black bean and pigeon pea seeds were subjected to appropriate processing methods before being milled into flour. Composite flour blends containing varying proportions of wheat flour, black bean flour, and pigeon pea flour were formulated and used to produce bread following standard baking procedures. The bread samples were analysed for selected micronutrients and phytochemicals using standard analytical methods. The data obtained were subjected to appropriate statistical analysis to determine significant differences among the samples. The results revealed that incorporating processed black bean and pigeon pea flours significantly improved the micronutrient composition of the bread samples. Phosphorus content ranged from 26.13 to 50.07 mg/100 g, iron from 0.73 to 1.70 mg/100 g, calcium from 139.60 to 202.23 mg/100 g, magnesium from 102.28 to 163.03 mg/100 g, and potassium from 134.24 to 312.00 mg/100 g. Similarly, vitamin content increased with increasing substitution levels of the processed legume flours. Vitamin B₁ (thiamine) ranged from 0.19 to 0.62 mg/100 g, vitamin B₂ (riboflavin) from 0.19 to 0.58 mg/100 g, and vitamin B₃ (niacin) from 0.20 to 1.01 mg/100 g. Alkaloid content varied from 2.03 to 4.98 mg/100 g, while flavonoid concentration ranged from 0.50 to 0.93 mg/100 g. The progressive increases in iron, phosphorus, calcium, magnesium, potassium, vitamins B₁, B₂, and B₃, alkaloids, and flavonoids with increasing levels of black bean and pigeon pea flour substitution indicated that the processed legumes were useful sources of essential micronutrients and functional phytochemicals. The processing methods employed reduced the undesirable effects commonly associated with legumes while enhancing nutrient availability and maintaining desirable bread-quality characteristics. The enriched breads therefore exhibited improved nutritional and phytochemical profiles compared with conventional wheat bread, indicating their potential as functional bakery products that may contribute to dietary micronutrient intake. In conclusion, processing black bean and pigeon pea before flour production positively influenced the nutritional quality of composite bread by enhancing micronutrient density and phytochemical content without compromising the overall quality attributes of the bread. The findings suggest that processed black bean and pigeon pea flours have potential as functional ingredients for composite bread production and may support efforts to address micronutrient deficiencies, improve food security, add value to underutilised legumes, and develop healthier bakery products.