Winsor behaviour of sucrose fatty acid esters: choice of the cosurfactant and effect of the surfactant composition

The behaviour of various sucrose fatty acid esters blends in pseudoternary mixtures {water/methyl stearate/sucrose ester+propanol or ethanol} was explored. The qualitative and quantitative analysis of the phases gave information on the distribution of the surfactant and the oil in the polyphasic systems. It was seen that the transitions between Winsor systems of type I–III can be obtained by using propanol as cosurfactant. Transition from a Winsor I behaviour to a Winsor II behaviour was observed, depending on the substitution degree of the sucrose ester. Marked differences can also be seen by this method between sucrose esters blends containing same contents of monoesters, but differing by the content of minor products, especially soaps. The Winsor behaviour can thus be used as a ‘fingerprint’ to distinguish different sucrose ester batches.