Gelation behaviour and rheological properties of acid-induced soy protein-stabilized emulsion gels

The protein concentration dependence on the rheological properties of acid-induced gels formed with unheated and heated soy protein-stabilized emulsions (UHSPE and HSPE) was investigated at different acidification temperatures. Pre-heat treatment on soy protein solutions resulted in a higher storage modulus (G′) and a shorter gelation time (t_gel) of acid-induced emulsion gels. A maximum in tan δ was observed in the UHSPE gels but no maximum was detected in the HSPE gels. Increasing the acidification temperature decreased the G′ and t_gel. The dependence of the G′ on the protein concentration (c) can be scaled with a power law: G′ ∼ c^A. The exponent (A) increased with pre-heat treatment and acidification temperature. The experimental data.fitted the fractal scaling model (G′ ∼ φ^A) and the simple time- scaling model above very well for the acid-induced soy protein-stabilized HSPE gels with varying oil volume fraction. The large deformation and fracture properties were significantly affected by soy protein concentration, pre-heat treatment, acidification temperature and volume fraction of oil droplets (p < 0.05).