Influence of protein type on Polyglycerol Polyricinoleate replacement in W/O/W (water-in-oil-in-water) double emulsions for food applications

In most publications concerning edible W/O/W-emulsions, the low-HLB emulsifier polyglycerol polyricinoleate (PGPR) is used to stabilize the W/O-interface in combination with a high-HLB emulsifier which stabilizes the O/ W-interface. Therefore, PGPR was used as the reference low-HLB emulsifier and compared to two alternative low-HLB emulsifiers namely ammonium phosphatide (AMP) and low-HLB sucrose ester O-170. As high-HLB emulsifiers both random coil (sodium caseinate) and globular proteins (whey protein isolate) were used. Hereby, the use of WPI led to similar, high enclosed water volume fractions for all used low-HLB emulsifiers whereas the use of Na-Caseinate led to almost no enclosed water in the emulsions containing ammonium phosphatide. Finally, the influence of osmotic pressure gradients on the release of an enclosed compound was examined. Therefore, the W/O/W-emulsions were diluted in iso-, hypo-and hypertonic solutions after which the release of an enclosed marker compound was followed over time. Hereby, AMP-and O-170 stabilized W/O/W-emulsions released the enclosed marker due to swelling under hypotonic dilution whereas hyper-and isotonic dilution never led to release of the enclosed marker, regardless of the used low-HLB emulsifier