Aroma compounds retention and release from protein-polysaccharide-based bilayer emulsion gels: A thermodynamic and kinetic study

Abstract

Thermodynamic and kinetic behavior of five aroma compounds (ACs) with different molecular structures in bilayer-stabilized emulsion gels (BEGs) depending on starch type (ST) and starch concentration (SC) during refrigerated storage time (RST) was investigated. The internal phase of BEGs was stabilized by myofibrillar proteins (MPs) and gum arabic, while the external phase was thickened and texturized with MPs and starches (waxy maize starch, potato starch) differing in amylose/amylopectin ratio. Oscillatory and rotational shear modes were used to evaluate rheological properties of BEGs, and the results are presented in terms of: Herschel-Bulkley parameters, quality factor and divergence from the Cox-Merz rule, which were modeled using a first order kinetic equation. Thermodynamic models composed of myosin and ACs were applied to determine the Stern-Volmer quenching constants, binding and thermodynamic parameters: enthalpy (ΔH), entropy (ΔS) and Gibb’s free energy (ΔG). Retention (R), release rate constant (kr) and mechanism of release (nr) values were significantly (p ≤ 0.05) dependent on: ST, SC and ACs type. After 12 days of refrigerated storage, the R values were ranged from 0.34 to 0.77, whereas those of kr and nr determined during RST were in ranges 6.21–102 × 10−3 (day−1) and 0.55–0.86, respectively. The gas-BEGs partition coefficient (kg/e) of ACs was measured at thermodynamic equilibrium and the enthalpy of vaporization was calculated from the variations of kg/e with temperature changes (30–60 °C). From a practical point of view, these results may have important implications for the development of commercial emulsion-type food with controlled ACs retention during RST.