Formation and characterisation of mint oil/S and CS/water microemulsions

Preparation and characterisation of microemulsions (ME) with mint oil (MO) as the oil phase were conducted to find a system which could provide a controlled, sustained, and prolonged delivery of MO. The influence of surfactant type and processing parameters on the formation of MO-ME’s was studied by comparing the areas of the monophase ME regions in pseudoternary phase diagrams. A 1:1 mixture of the surfactants, AOT and CrEL, was found to be the most effective, and it produced a ME monophase area of about 70%. The monophase regions were analysed by conductivity measurements; the results suggested that O/W regions within the ME phases were formed when the water content was higher than 60–65%. As tested with dynamic light scattering (DLS) and head space (HS) GC analysis, the particle size of O/W ME, with 60% water and AOT/CrEL = 1:1 as surfactants, was 20.0 nm and the encapsulation efficiency was 78.4%. The results indicated that a ME of MO/AOT and CrEL/ethanol/water, may be a promising dispersion for the protection of MO in food products.