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The effect of shear on the rheology and structure of heat‐induced whey protein gels

Badii, Fojan, Atri, Halleh, Dunstan, Dave E.
International journal of food science & technology 2016 v.51 no.7 pp. 1570-1577
deformation, gelation, gels, light microscopy, microstructure, modulus of elasticity, protein content, rheology, rheometry, separation, storage modulus, viscoelasticity, whey protein
The influence of mechanical shearing on the small deformation properties and microstructure of heat‐induced whey protein gel has been studied. The viscoelastic properties of these gels at different concentrations of 10% and 20% (w/w) exposed to different shear rates of 0, 50, 100, 200 and 500 s⁻¹ during gelation were measured using dynamic oscillatory rheometry. The structure of both the shear treated and unsheared gels was then investigated using light microscopy. The results showed that the storage modulus of the gels at both concentrations was increased by increasing the shear rate exposure during gelation while the shear‐treated gels were more elastic and showed frequency‐independent behaviour. As the total protein concentration of the gel increased, the viscoelastic properties of the gels also increased significantly and the gels showed greater elasticity. The gels obtained from the higher shear rate exposure were stronger with higher elastic moduli at both protein concentrations. Images of the gels obtained using light microscopy showed that shearing resulted in phase separation and some aggregation in the structure of the gels at both concentrations. However, the shearing rates applied in this study were not enough to cause aggregation breakdown in the gel network.