Functional analysis of mildly refined fractions from yellow pea

Dry fractionation offers an attractive route to sustainably produce protein-enriched plant-based ingredients. For example, fine milling of peas followed by air classification separates starch granules from the protein matrix. Unlike conventional wet isolates, dry-enriched pea fractions consist of a mixture of protein, starch and fibre, but have the advantage that protein retains its native state. In this context, dry-enriched pea ingredients were assessed for their functionality in terms of gelatinization and phase behaviour. After suspension in water, starch, protein and fibre separated into distinctive layers. The top layers were concentrated by ultrafiltration into a native protein-rich concentrate with a purity of 67 g protein/100 g dry matter and a protein yield of 63%. Upon heat-induced gelatinization, gel firmness was mainly increased by the presence of starch, while the presence of dispersed components (i.e. protein and/or fibre patches) in the gel weakened its structure. The heating and cooling rates influenced the firmness of the gel prepared from flour. The fine fraction could be gelled by protein crosslinking using transglutaminase. The increased protein gel strength in the presence of dispersed fibre and starch was explained by their water absorption leading to concentration of the protein phase. In conclusion, all pea fractions could be used to prepare firm gels, despite their different compositions, which supports recent insight that development of novel food ingredients should focus on functionality rather than on molecular purity. Finally, the combination of dry and aqueous phase separation is proposed as a more sustainable route compared to conventional wet extraction processes.