Dry Heating of Cowpea Flour below Biopolymer Melting Temperatures Improves the Physical Properties of Bread Made from Climate-Resilient Crops

To address food security in Sub-Saharan Africa, researchers are increasingly looking toward climate-resilient crops (CRCs) like cowpea, sorghum, and cassava. However, using these crops in bread-making is challenging due to their lack of gluten and unique physicochemical properties. This study investigated whether dry heating cowpea flour (CPF) could serve as a simple, chemical-free method to improve its functional performance in bread. The researchers first modeled the melting behavior of cowpea starch and proteins using Flory–Huggins theory to identify optimal, non-destructive heat treatment conditions. They then tested various temperature-time combinations (80–120 °C for 2–48 hours) to observe changes in water-binding capacity, pasting properties, and final bread quality.

The researchers found that dry heating could selectively modulate the flour's pasting properties without fully denaturing the starch or proteins. Specifically, heating at 100 °C for 2 hours resulted in a reduction in breakdown viscosity, which indicates improved starch integrity. When this treated flour was incorporated into a composite bread recipe (sorghum, cassava, and cowpea), it significantly improved the crumb texture compared to bread made with native flour. The treated bread exhibited greater softness, cohesiveness, and resilience, likely because the heat-treated proteins formed a more stable structure that supported the starch matrix during baking.

This research provides a low-cost, sustainable, and scalable technology for small-scale bakeries in regions where wheat imports are expensive or unreliable. By using simple dry-heating techniques, producers can transform locally available, climate-resilient legumes into high-quality, functional ingredients for staple foods. This approach not only supports local agriculture but also enhances the nutritional and physical quality of bread, contributing to better food security and economic stability for smallholder farmers.