Shear effects on the rheology of β-lactoglobulin/β-carrageenan mixed gels

Rheological and microstructural effects of preshear treatment on heat-induced pure β-lactoglobulin gels and on mixed gels of 5% β-lactoglobulin and 1% κ-carrageenan have been investigated at pH 5. No salt was used in this work. The shear process with different rate/time combinations was performed just before the gel formation. During the cooling process from 90 to 20 °C, the values of elastic moduli G′ of the pure protein gels showed a mono-continuous profile, whereas the mixed gels showed a bicontinuous profile which indicated the formation of phase-separated gels. The values of G′ of both systems decreased with increase of shear rate and shear duration, and the profiles of G′ could not be modified by shear treatment. The Confocal microscopy revealed that the network structures of the gels have been broken by preshear treatment.