Combined effects of temperature and elasticity on phase separation in mixtures of κ-carragheenan and β-lactoglobulin aggregates

The effect of protein aggregate morphology on phase separation in mixtures with polysaccharides

“…The critical κ-car concentration needed to induce phase separation depended only weakly on the protein concentration as was already reported for β-lg strands (Nguyen et al 2014) and fractal aggregates (Baussay et al 2006, Croguennoc et al 2001a. A systematic investigation with microgels of different sizes (R h = 130-350 nm) confirmed this observation (data not shown).…”

“…It has been suggested that depletion of the κ-car chains is the origin of the formation of dense domains of protein aggregates (Tuinier et al 2003). However, we have shown that, very close to the critical concentration, microphase separation can be reverted by increasing the temperature (Nguyen et al 2014). Since the depletion interaction is entropic no temperature dependence would be expected if it was the main driving force.…”

“…However, we have two reasons to believe that depletion is not the principal driving force for phase separation in these mixtures. Firstly, we showed recently (Nguyen et al 2014) that phase separation was reduced at higher temperatures, which is expected in the case of thermodynamic incompatibility, but not for depletion interaction, which is purely entropic. Secondly, the κ-car concentration is not strongly reduced within the protein rich domains.…”

“…When κ-car chains are added to a stable suspension of β-lg aggregates at room temperature, the two components phase separate above a critical concentration of κ-car. This phenomenon has been studied in some detail for mixtures of κ-car with small strand-like β-lg aggregates and with larger self-similar aggregates formed by secondary aggregation of the strands (Baussay et al 2006, Croguennoc et al 2001a, de Jong et al 2009, Gaaloul et al 2010, Nguyen et al 2014. It was shown that the critical concentration of κ-car to induce phase separation is about 8 g L − 1 for the strands (Nguyen et al 2014) and it decreases strongly with increasing aggregate size (Baussay et al 2006).…”

“…This phenomenon has been studied in some detail for mixtures of κ-car with small strand-like β-lg aggregates and with larger self-similar aggregates formed by secondary aggregation of the strands (Baussay et al 2006, Croguennoc et al 2001a, de Jong et al 2009, Gaaloul et al 2010, Nguyen et al 2014. It was shown that the critical concentration of κ-car to induce phase separation is about 8 g L − 1 for the strands (Nguyen et al 2014) and it decreases strongly with increasing aggregate size (Baussay et al 2006). The critical κ-car concentration decreased weakly with increasing protein concentration.…”