Protein enrichment and its effects on gluten-free bread characteristics

Protein-enriched, rice-based flours, composed of casein and albumin protein isolates as well as transglutaminase for reinforcing protein networks, were designed for optimising a gluten-free formulation suitable for breadmaking. Experimental design resulted in composite protein-enriched blends with different pasting, mechanical and surface-related textural properties. The presence of transglutaminase resulted in a significant decrease of all the protein fractions, which suggested protein crosslinking. Protein isolates significantly (p < 0.05) modified the gelatinisation and gelling behaviour of the flour, reducing both its peak viscosity and final viscosity. The textural properties were primarily affected by the addition of casein and transglutaminase. The design allowed the determination of the optimum formulation for obtaining the highest specific volume of gluten-free baked product with the lowest crumb hardness by combining transglutaminase (1.35 U of enzyme/g of rice flour protein), egg albumin (0.67 g/100 g of flour) and casein (0.67 g/100 g of flour). The use of albumin and casein protein isolates and transglutaminase constitutes a promising approach to producing protein-enriched blends for making fermented, gluten-free products.

► Experimental design resulted in composite protein-enriched blends. ► The presence of transglutaminase resulted in decrease of all the protein fractions. ► Protein isolates modified the gelatinisation behaviour of the flour. ► Textural properties were affected by the addition of casein and transglutaminase. ► Better specific volume was obtained with minor amounts of protein and enzyme.