4. Conclusions
In this work, different concentrations of hydrogen bond-forming agents (citric acid (CA), ascorbic acid (AA), low methoxyl pectin (LMP)) with and without salts (sodium chloride (S) or calcium chloride (Ca)) was added into the aqueous phase to investigate the stability of the liquid W/CO and W/MO emulsions with a small molecule emulsifier, GMO. W/CO emulsion without additives destabilized instantly, whereas W/MO emulsion stayed partially stable due to extensive hydrogen bonds between GMO and CO TAG glycerol polar heads, leading to the desorption of interfacial GMO towards the CO phase. In MO, GMO favoured interfacial adsorption due to the lack of polar groups, leading to emulsion stability. The addition of hydrogen bond-forming agents and salts in the aqueous phase significantly improved both the CO- and MO-emulsion stability. LMP, with a large number of hydrogen bond-forming groups, was able to provide the highest emulsion stability after 7 days in both oils compared to AA, CA and their mixtures with S. However, the presence of Ca with LMP led to gelation in the aqueous phase which prevented interfacial interaction of LMP with GMO leading to a lowering of emulsion stability. Emulsions with both oils formed weak gels due to the formation of an extensive network of water droplet aggregates. Water droplets were smaller in MO-emulsions than CO-emulsions, leading to a more extensive droplet network in the former which provided higher stability against phase separation and preservation of viscosity after 7 days storage. Interestingly, the droplet network in MO-emulsions broke down at a lower crossover stain than the CO-emulsions, indicating weaker links between the droplets. Overall, the aqueous phase hydrogen bond-forming agents interacted with GMO at the interface allowing improved stability of GMO-stabilized liquid W/CO emulsions. This important finding could facilitate the development of highly stable food-grade low-saturated fat tablespreads. The knowledge developed could also improve our understanding of stability mechanisms in W/O emulsions for other industrial and cosmetics applications.