Evaluation of drops dimensions in time and rheological properties of the multiple emulsion

Abstract

Results of drops dimension and rheological properties of the produced multiple emulsion are presented in this paper. Sunflower oil (oil phase), distilled water (liquid phase), and lecithin from soya beans were used as materials to produce emulsion. Emulsions were produced in vessel with inner diameter D = 0.1 m and liquid height H = 0.5D. Smith turbine has been used to stir the emulsions. Examination of the drops dimension and rheological properties were conducted for emulsions collected after 15 min and 45 min of stirring as well as after the 3rd and 30th day. There were 6 measurements altogether. To do the analysis of drops dimension, in each series 700-800 inner oil-phase drops were taken. The results were presented in a form of graphics as a distribution of drops. The dimensions of the drops obtained d were also presented as a minimal diameter d min , arithmetic mean diameter d a , median d m , and Sauter mean diameter d 32. The results of the research of rheological emulsions were presented graphically as a viscosity curve and they were described by Herschel-Bulkley model (Eq. 4) Keywords Multiple emulsion • Microscopic analysis • Rheological measurements List of symbols B Width of the baffles (m) D Inner diameter of the vessel (m) d s Diameter of the stirrer (m) d Diameter of the drop (µm) d a Arithmetic mean diameter of the drop (µm) d m Mediana diameter of the drop (µm) d 32 SAUTER mean diameter (µm) d 43 Volume-weighted mean diameter (µm) H Liquid height in the vessel (m) J Number of baffles n Stirrer speed Z Number of stirrer blades (s −1) Greek letters τ Shear stress (Pa) γ Shear rate (s −1)

Particle size distribution and homogenisation efficiency in high‐pressure homogenisation of wheat germ oil‐water system

“…Measurements were taken by Phase Doppler Particle Analyzer (PDPA). Mean droplet diameter was expressed as the Sauter diameter ( D 32 ) (Major‐Godlewska, 2019). …”

The influence of stirring time and frequency of impeller rotation on evaluation of drops dimensions and rheological properties of the multiple emulsion

“…The values obtained when 16 g of lecithin was used during the emulsion production where the stirrer rotation frequency was 500 rpm were marked as points. The values obtained with the equation presented by Major-Godlewska (2019) were marked as line. The larger amount of lecithin in the emulsion increases the value of shear stress τ assuming the same constant shear rate γ.…”