Linear viscoelastic assessment of cold gel-like emulsions stabilized with bovine gelatin

Abstract

Gel-like oil-in-water emulsions with low lipid content, stabilized with bovine gelatin of different molecular weights were analyzed. Mean droplet size and droplet size distribution of the emulsions were determined by static light scattering. The emulsions were characterized for their rheological properties using dynamic oscillatory and creep-recovery tests in the linear viscoelastic region. Most of the systems exhibited gel-like properties even the samples were not submitted to thermal treatment and the temperature was maintained below 30 °C; this viscoelastic characteristic led to a delay of the phase-separation exceeding one month. Creep-compliance data were fitted to a four parameters Burgers model. The continuous relaxation spectra were estimated from the experimental values of G′ and G″ considering the Baumgaertel – Schausberger – Winter generalized model. Discrete relaxation moduli and relaxation times were derived from the continuous spectra. The effect of molecular weight of the protein and the stability during the storage at 20 °C was analyzed in order to interpret the structural characteristics of these emulsions.