Enhancing the Stability of Oil-in-water Emulsion Using Pectin-lactoferrin Complexes

The present study investigated on the emulsifying properties of natural low-methoxyl pectin (LMP) extracted from Green Jelly Leaf (GJLP) in stabilising lactoferrin stabilised oil-in-water emulsions. The emulsion stability of GJLP was compared to commercial pectins with different degree of esterification (DE) i.e. high-methoxyl pectin (HMP) and LMP. The influence of pH, pectin types and concentration on the stability and physical properties of emulsions were evaluated by determining zeta potential value, particle size, microstructure, rheological properties and creaming stability. Different types of pectin exhibited different mechanisms in providing the emulsion stability and the pectin effective charge was strongly dependent on its DE and pH of the continuous phase. The mechanism of actions of pectin and lactoferrin in the system were pH dependent for low molecular weight pectin, however not for high molecular pectin such as GJLP. The results showed that the complexes formed by pectin and lactoferrin at the interface were not sufficient to maintain the emulsion stability. This study also showed the important of unabsorbed pectin molecules in continuous phase in providing the physical stability of emulsion. These molecules formed a thick multilayers surround oil droplets. In addition, the incorporation of 0.2% w/w of GJLP could produce a stable emulsion, suggesting the potential use of GJLP to improve the stability of lactoferrin stabilised oil-in-water emulsions.