Impact of soya protein isolate and Fonio flour on the rheological and microstructural properties of bread

Abstract

This study investigates the impact of Soya Protein Isolate (SPI) and Fonio Flour (FF) on the rheological and microstructural properties of bread. As bread is a staple food consumed globally, there is a growing interest in enhancing its nutritional value, particularly for gluten-sensitive and plant-based diets. SPI, a plant-based protein rich in essential amino acids, and FF, a gluten-free flour from the African grain fonio, were incorporated into wheat flour at varying levels. The primary objectives of the study were to assess the effects of SPI and FF on dough rheology, bread microstructure, and sensory characteristics. The dough was prepared using different concentrations of SPI (5%, 10%, 15%) and FF (10%, 20%, 30%), and rheological properties such as water absorption, dough development time, and stability were measured using a Mixolab. The bread was baked and analyzed for microstructural properties through scanning electron microscopy (SEM), and sensory attributes were evaluated by a panel of 30 trained tasters using a 9-point hedonic scale. The results indicated that the incorporation of SPI and FF significantly improved the rheological properties of the dough, with higher SPI and FF concentrations resulting in increased water absorption, dough development time, and stability. SEM images revealed a more uniform and finer crumb structure with improved porosity in breads made with SPI and FF, particularly at the 10% SPI and 20% FF levels. Sensory evaluation showed that the bread formulated with 10% SPI and 20% FF received the highest scores for taste, texture, and overall acceptability. In conclusion, the incorporation of SPI and FF enhances both the nutritional content and texture of bread. These findings suggest that SPI and FF can be used effectively in the development of functional, gluten-free bread with improved sensory and nutritional qualities, offering a promising option for health-conscious consumers.