2.5.1. Determination of Particle Size Changes in the Emulsion Samples and Optical Microscope Observations of Emulsions

The particle size distribution of emulsions was performed using a Mastersizer 2000 (Malvern Instrument Ltd., Worcestershire, UK). The initial and reconstituted emulsion samples were gently diluted with 0.1% SDS solution, then dispersed in distilled water (stirred speed—2000 rpm) to obtain an obscuration rate of 10%. The optical properties of the sample were defined as follows—refractive index 1500 and absorption 1.00. Droplet size measurements were described as the volume-weighted mean diameter d_4,3 = ∑n_id_4i/∑n_id_i3 and d_3,2 = ∑n_id_3i/∑n_id_i2, where n_i is the number of droplets of diameter d_i [5].

Samples of initial and reconstituted emulsions were mixed in the ratio 1:1 with 0.5% SDS. The Sudan III was added as an oil dye to obtain a contrast. The initial and reconstituted emulsions were observed at 25 °C, using a digital camera connected to a microscope (OptaTech, Warsaw, Poland) at a magnification of ×10.