Abstract
Flavour release and emulsion stability depend on volatile organic compounds' environmental conditions, food microstructure, and physicochemical properties. The effect of pH (3.5 vs 7.0) and saliva addition on stability and flavour release from nano and conventional emulsions was investigated using particle size, charge and Lumisizer measurments. Larger particle sizes were observed at lower pressures and in saliva-containing emulsions. At 1700 bar, nano-emulsions (below 150 nm) were created at pH 3.5 and 7.0 including saliva-containing emulsions. As was clear from the creaming velocity measurements, saliva addition decreased the emulsion stability by reducing particle charges and increased viscosity by more than 50%, especially when prepared at pH 3.5 closer to the isoelectric point of the used emulsifier β-lactoglobulin (pH 5.2). (5.2). Flavour release from emulsions was measured at equilibrium using a phase ratio variation to determine partition coefficients and dynamically using an electronic nose. Partition coefficients of the flavour compounds for most conditions were two to four times lower in emulsions prepared at pH 7.0 than at pH 3.5 and in emulsions without saliva. Emulsions prepared with higher pressures showed stronger flavor release rates, while additional salvia dropped the release rate for ethyl acetate at pH 3.5. The physicochemical properties of flavour compounds, saliva addition and pH of emulsions influenced flavour release more than homogenization pressures. The potential in using nano-emulsions in food applications an be attributed higher stability and enhanced flavor release.