Effects of production parameters on the stability of multiple emulsions
The composition and production parameters of the formulations investigated in this study are shown in Tables 1 and 2.
The first step of the study was to optimize the production parameters. Datas obtained in case of optimized conditions for primary emulsion formulation is as follows: optimal oil phase volume was found as 20 %, surfactant was chosen among the ones tested namely Span 20, Span 80, Span 20–80 (1:1) and ABIL EM 90. We have conducted the studies
with all of these and since ABIL EM 90 gave the most satisfactory results, it was chosen and used in our study, mixing time was chosen as 15 min. and mixing rate as 1500 rpm and additional 15 min. with 800 rpm respectively. Temperature was maintained as 80ºC. Magnesium sulphate was added as an electrolyte to the inner water phase.
Datas obtained in case of optimized conditions for emulsion formulation is as follows:
optimal primary emulsion phase volume was chosen as 80 %. Mixing time and rate were
45 min. 500 rpm for the second step emulsification.Hydrophilic surface active agent was
chosen to be Tween 80 among the others tested. Addition of the primary emulsion to the
outer water phase was found to be slowly by small portions. Optimal preparation condition
for temperature was found as 25ºC. In order to increase the density of the outer phase of
multiple emulsion, 2 % Carbopol 934 was used. As mixing shaft, triple propeller mixer was
chosen.
Organoleptic and microscopic investigations, particle size analysis, centrifuge tests,
rheological analysis were carried out and stability tests were performed at various
temperatures on all formulations as usually done to assess stability of multiple emulsions
[14].