Ultrafiltration for homogenization of wheat germ oil:water system: Droplet size distribution and stability of emulsion

Abstract

Wheat germ oil (WGO) in water emulsion is increasingly being used in a variety of fields due to its outstanding nutritional and health benefits. To enhance WGO composability, emulsification should be performed to allow them to dissolve more easily in the food matrix or active packaging. Membrane emulsification is a promising advanced homogenization technology that has recently been developed. This research focused on application of membrane emulsification for homogenization of WGO-in-water emulsion polyether sulfone (PESU) membrane with 0.45 µm of pore size, operating pressure from 5 to 9 bar, with WGO fraction in range 10 – 20% w/w and lecithin ratio in range 0 – 0.2% w/v were evaluated on the mean of particle diameter, distribution of particles diameter, stability of emulsion, and permeate flux. Higher operating pressure led to smaller mean particle diameters, higher homogenization efficiency and permeate flux. However, increasing the WGO fraction showed the opposite trend. Notably, increasing lecithin ratio from 0 to 0.2%, the mean particle diameter increased from 3.36 to 7.72 µm, homogenization efficiency decreased from 98.54 to 97.68%, and permeate flux decreased from 105.95 to 77.45 L.h-1.m-2. The results showed the advantage of using PESU membrane in WGO-in-water homogenization, that produce emulsions with small particle size (50% of particle volume was less than 5µm), high emulsion stability (greater than 95%) and lower emulsifier usage. Results imply premix membrane emulsification is potential to apply homogenization WGO-in-water emulsion.