Phase separation, rheology and microstructure of pea protein–kappa-carrageenan mixtures

Due to their interest in food industry, mixed systems of globular proteins and polysaccharides have been the subject of growing interest in recent years. In the particular case of this work, the focus is on mixtures of pea-protein–kappa-carrageenan. Phase diagrams of pea protein and κ-carrageenan mixtures have been established at pH 7 above the isoelectric point (IEP) of the protein, 60 °C and two different ionic strengths (0.05 and 0.2 M). These systems led to phase separation probably arised by the depletion–flocculation mechanism. Under the same conditions, rheology and microstructure by confocal laser scanning microscopy (CLSM) of these systems in the mono and biphasic regions have been investigated. CLSM showed the formation of pea protein aggregates network in presence of κ-carrageenan. Marked differences between mixtures in two-phase region and one component solutions were also evidenced in the rheological properties, with the behaviour being governed by the continuous protein-enriched phase.