Vitamin D3 and phytosterols affect the properties of polyglycerol polyricinoleate (PGPR) and protein interfaces

The present work tested the effect of addition of hydrophobic compounds at interfaces containing polyglycerol polyricinoleate (PGPR) and beta-lactoglobulin or sodium caseinate, using drop tensiometry. Vitamin D3 or phytosterols were also tested on a model double emulsion stabilized with PGPR and sodium caseinate. Emulsions were prepared using a high pressure homogenizer, and changes in particle size were followed using light scattering. The encapsulation efficiency of the double emulsions was estimated by adding Mg2+ and measuring its release from the inner droplet. PGPR dominated the oil-water interfacial properties. In the presence of proteins there was a decrease of the interfacial tension, with little changes in the viscoelastic properties. The presence of vitamin D3 and phytosterols further affected the interfacial properties. Double emulsions were then prepared with 2% PGPR. While control emulsions showed limited stability with an increase in the particle size after one week of storage, emulsions containing 0.05% (w/w) of vitamin D3 or phytosterol resulted in better stability over the storage period. Results suggested that vitamin D3 and phytosterol molecules may interact with the emulsifiers at the interface, affecting the physico-chemical properties, and possibly their release during digestion. (C) 2015 Elsevier Ltd. All rights reserved.