Nutritional Characterization of Selected South African Indigenous Seed Flours and Their Impact on Bread Baking...

Diets based predominantly on refined cereal staples are associated with inadequate intake of high-quality protein and essential micronutrients. This study evaluated five underutilized South African indigenous seed flours, Lowveld chestnut (Sterculia murex), marula (Sclerocarya birrea), forest mahogany (Trichilia dregeana), Natal mahogany (Trichilia emetica), and stamvrug (Englerophytum magalismontanum), as functional ingredients in composite bread at 10%-20% substitution levels. Analyses included proximate composition, amino acid and mineral profiles, phenolic content, microbial quality, dough rheology (Mixolab), and bread baking performance using C-Cell and texture analysis. The flours exhibited distinct compositional profiles, with marula characterized by high protein and lipid content and Lowveld chestnut contributing favorable essential amino acid composition. Incorporation into wheat dough reduced dough strength, especially in lipid-rich formulations, while stamvrug increased dough stiffness. These rheological differences were also reflected in crumb structure and firmness development during storage. Marula and mahogany breads exhibited more open crumb structures and reduced firming, whereas stamvrug produced dense crumb structures and accelerated firming. Baking reduced microbial loads; however, changes during storage emphasized the need for appropriate control of raw materials and postbaking handling. Among the seed flours evaluated, marula and Lowveld chestnut provided the most favorable balance between nutritional improvement and baking performance, demonstrating the potential of underutilized indigenous seed flours as high-value functional ingredients. PRACTICAL APPLICATIONS: This research demonstrates the potential of locally available indigenous seeds for developing nutritionally enhanced bread to benefit communities and the food industry.