Developing Protein-Enriched Wholegrain Bread With Different Plant Protein Isolates

Bread is a widely consumed staple food across the world; however, it often lacks a complete amino acid profile. This study aims to determine the suitability of commercially available plant protein isolates for the development of protein-enriched wholewheat bread, while preserving desired quality characteristics. Three protein isolates, soy protein isolate (SPI), pea protein isolate 1 (PPI1), and pea protein isolate 2 (PPI2), were assessed for their structural and functional properties, then incorporated in wholegrain bread formulations at 5%, 10%, and 15%, followed by assessment of dough properties and end-use baking quality. The protein content of the isolates ranged from 80% to 90%, with PPI2 having the highest protein concentration. SPI had the highest denaturation temperature at 85.54°C ± 0.31°C and exhibited superior foam and emulsion stability at 81.94% and 94.21%, respectively. PPI1 had the highest solubility at 20.85%, whereas PPI2 had the highest surface hydrophobicity value at 152,645. Additionally, SPI formed the strongest gels with the lowest minimum gelation concentration of 12%. Increasing the protein concentration in the bread formulations resulted in a decrease in firmness, loaf volume, and specific volume. Breads with the 5% SPI had the highest loaf volume of 342 ± 7.6 mL, favorable textural properties, and L* values of 39.40 ± 2.13 for the crust and 45.83 ± 1.57 for the crumb, making it the more suitable protein isolate for protein-enriched bakery applications. The addition of plant-based proteins presents a viable solution for addressing the increasing consumer demand for both nutritious and sustainable food options.