Pomegranate peel pectin can be used as an effective emulsifier

Abstract

In this study, pomegranate peel pectin was extracted by hot water at 86 °C and pH 1.7 for 80 min. The pectin yield was 8.5%, with the uronic acid content of around 62.0%. Structural characterization suggested that the pectin was high-methylated (DM = 75%) and mainly composed of rhamnose (4.5%), xylose (13.4%), mannose (1.8%), glucose (60.8%) and galactose (19.5%). FTIR analysis indicated that the pectin contained a high amount of ester groups, which is generally considered as one kind of the hydrophobic groups in pectin molecules. The emulsifying property assessments suggested that when the pectin concentration was increased to 2.0% (w/v), a stable emulsion containing 50% oil phase (v/v) can be obtained. Although pH significantly affected the emulsifying properties, the pectin dispersion (1.0%, w/v) still exhibited good emulsifying stability at pH 2.0–6.0. Furthermore, it was found that low Ca2+ concentrations (below 60 mg/g pectin) improved the emulsifying stability by elevating the viscosity of continuous phase, whereas high Ca2+ concentrations was unfavorable to emulsion stabilization. As the Na+ concentration increased from 0 to 200 mg/g pectin, the emulsion stability was observed to be decreased, which may be because Na+ shielded the negative charges in pectin molecules and thus decreased the repulsions between emulsion droplets. Overall, our results indicate that pomegranate peel pectin can act as an effective emulsifier, and the present study may provide relevant reference for searching natural emulsifiers that can be used in the food industry.