The influence of heat and mechanical stress on encapsulation efficiency and droplet size of w/o/w multiple emulsions

Heat treatment and mechanical movement are the most common stressors that affect food material processing. A w/o/w emulsion is a promising system for delivering sensitive materials in food products and in reducing dietary fat content, but for wider uses, it is necessary to evaluate emulsion behaviour during food manufacturing. In the present study, we simulate heat (5 to 85 degrees C) and mechanical processes (shear rate 0.1 to 1000 s(-1)) using rotational rheometry and describe changes in glucose encapsulation efficiency and droplet size of model w/o/w 20% emulsions prepared with 2.5 wt % PGPR (polyglycerol polyricinoleate) as lipophilic emulsifier in canola oil (oil phase) and distilled water or 10 wt % skim milk as an internal water phase stabilized or not by 3 types of carrageenan (0.5 wt %) and milk proteins as emulsifier. The comparison of w/o/w emulsions prepared with three specific types of carrageenan provides the important information on the suitability of the combination of specific carrageenan and internal water phase. It was found that model manufacturing did not influence the result encapsulation efficiency of all w/o/w emulsions significantly. We demonstrated that model w/o/w 20% emulsions were sufficiently stable for manufacturing, especially when skim milk was used with 0.5 wt % kappa carrageenan as the internal water phase. These samples subjected to manufacturing showed an encapsulation efficiency 53.97 +/- 0.00% even after 4 weeks storage at 4 degrees C and droplet size (D[4, 3]) 39.04 +/- 1.56 mu m. So prepared w/o/w emulsions provided the demanded stability and could be part of functional food.