Thermal reversibility of vitamin E-enriched emulsion-based delivery systems produced using spontaneous emulsification

The influence of temperature scanning and isothermal storage conditions on turbidity, particle size, and thermal reversibility of vitamin E-enriched emulsions produced by spontaneous emulsification was examined. Initially, the mini-emulsions formed were optically transparent and contained small droplets (d approximate to 44 nm). When heated (20-90 degrees C), emulsions exhibited a complex turbidity-temperature profile with a phase inversion temperature (PIT) at approximate to 75-80 degrees C. Temperature scanning rate had a major influence on emulsion thermal reversibility. Slow heating (0.5 degrees C/min) above the PIT followed by quench cooling (approximate to 67 degrees C min(-1)) to 30 degrees C did not appreciably increase turbidity or droplet diameter (d approximate to 50 nm), suggesting these systems were thermo-reversible. However, slow heating to temperatures below the PIT followed by rapid cooling appreciably increased droplet size and turbidity (thermo-irreversible). Cooling rate also affected emulsion thermo-reversibility: the turbidity and droplet size after heating above the PIT decreased with increasing cooling rate. (C) 2015 Elsevier Ltd. All rights reserved.