Rubisco: A promising plant protein to enrich wheat-based food without impairing dough viscoelasticity and protein polymerisation

Abstract

Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase), a leaf protein, has an interesting amino acid profile and promising functional properties. Incorporated in wheat-based products, it would increase their protein content and improve their essential amino acid profile, particularly lysine. The impact of rubisco enrichment on wheat dough mechanical properties and protein-protein interactions was investigated using Dynamic Mechanical Thermal Analysis and Size-Exclusion chromatography, respectively. Experiments were also performed on gluten and pea protein enriched doughs as a comparison. Wheat doughs with increasing concentrations of rubisco, gluten or pea proteins (from 0 to 33% of total proteins) were prepared using a 2 g-mixograph at constant hydration. In contrast to pea proteins and gluten, rubisco does not reduce dough stiffening during heating, probably due to its own reactivity to temperature and to low competition with starch for water. Detailed analysis of protein interactions showed that rubisco is part of the gluten network formed during dough mixing through the establishment of weak and disulphide bonds. In addition, rubisco subunits form new covalent bonds during the heat treatment thereby increasing the concentration of SDS insoluble high molecular weight aggregates. These results suggest that rubisco actively participates in the formation of the dough protein network. The colocation of gluten and rubisco proteins on micrographs supports the hypothesis that they form a co-protein network.