Freeze Thaw Stability and Heat Stability of Coconut Oil-in-Water Emulsions and Coconut Milk Emulsions Stabilized by Enzyme-Modified Soy Lecithin

This study investigated effects of enzyme-modified soy lecithin (ESL) on freeze thaw stability and heat stability of coconut oil-in-water emulsions and coconut milk emulsions. Addition of ESL improved freeze thaw stability of coconut oil-in-water emulsions and coconut milk emulsions. Mean droplet sizes of coconut oil-in-water emulsions contained 20 wt% oil and 9 wt% ESL did not significantly alter after emulsions being frozen at -20 degrees C for 22 h and thawed at room temperature. Relatively similar fat crystallization patterns obtained from differential scanning calorimetry after three cooling-heating cycles (40 degrees C to -40 degrees C to 40 degrees C at 5 degrees C/min) confirmed high freeze thaw stability of coconut oil-in-water emulsions. Increasing concentrations of ESL to 9 wt% reduced amounts of destabilized oil in freeze thawed coconut milk emulsions substantially. Heat stability study shows that coconut oil-in-water emulsions and coconut milk emulsions stabilized by 9 wt% ESL remained remarkably stable after heating at 121 degrees C for 1 h observed by microscopy and mean droplet sizes. This work reveals that ESL contained mostly of unsaturated lysophospholipids reduced partial coalescence during freeze thawing process and reduced protein coagulation, droplets flocculation, and coalescence during heating process. ESL partially displaced and possibly interacted with interfacial coconut proteins which increased stability of coconut milk emulsions.