Added ferulic acid enhances the emulsifying properties of pectins from different sources

This work aimed to study the influence of exogenous ferulic acid (FA) on the emulsifying properties of sugar beet pectin (SBP), citrus pectin (CP), and apple pectin (AP). Three series of pectin-FA solutions each containing 1% of AP, CP, SBP and 0.1-0.3% w/w FA were prepared, characterized and then used to fabricate oil-in-water emulsion (oil/aqueous phase ratio of 15:85 by weight). Fluorescence spectrum analysis confirmed hydrophobic associations between pectin and FA led to water solubility enhancement of FA. For each type of pectin, the interfacial and emulsifying activity was significantly enhanced by addition of FA. More importantly, the FA supplemented emulsions were more stable during storage at 60 degrees C for seven days, in comparison with their counterparts, but in a concentration-independent manner (0.1-0.3% w/w). In the three emulsions containing 1% of each type of pectin and 0.2% w/w of FA, the concentration of FA adsorbing onto oil-water interface (Gamma(FA)) was 6.44, 8.04, and 0.67 mg/m(2) for AP-, CP- and SBP-stabilized emulsions, respectively. Meanwhile, the concentration of pectin adsorbing onto oil-water interface (Gamma(pectin)) was significantly increased by the addition of FA for the AP- and CP-stabilized emulsions, but not for the SBP-stabilized emulsion. Comparison of the emulsification performances of each pectin and their enhancements by FA revealed the synergistic effect of FA in combination with AP and CP on emulsification was more pronounced than with SBP. Altogether, the combination of FA and pectin exerts an enhanced stabilizing effect for oil-in-water emulsions.