W/O濃厚エマルションのアルコール類による安定性変化とその評価法

抄録

A stability of W/O emulsions was generally evaluated by the flocullation of dispersed phase in the short-term. Several studies with respect to the evaluation of stability of W/O emulsions have been reported, however, the coalescence of dispersed phase was discussed in only a few studies. Hence, we have examined the coalescence of dispersed phase in concentrated W/O emulsions in coexistence with various alcohols by evaluating of interfacial film strength. Addition of ethanol or 1, 3BG (1, 3 butylene glycol) in the dispersed phase induced the decrease of COS 82 (Sorbitan Sesquioleate) adsorbed at the water-squalane interface, but in contrast, addition of glycerol did not change the adsorption of COS 82. COS 82 formed firm hydrophobic gel with glycerol, but not with 1, 3BG. Interfacial film strength was evaluated by using the ratio of freezing enthalpy of the structured water to that of the free water measured by differencial scanning calorimeter (DSC) in the temperature range of -50°C to 10°C. In case of 1, 3BG, freezing enthalpy of the free water was increased by the repetition of freezing. These results suggested an acceleration of the coalescence of dispersed phase with the addition of 1, 3BG. In case of glycerol, it suggested a tendency to be stable.
DSC freeze-thawing method was closely correlated with the above and the stability at the room temperature.