Stability of water-in-oil-in-water emulsions containing faba bean proteins

Abstract

For the case of water-in-oil-in-water (W/O/W) multiple emulsions made with low-molecular-weight Span 80 as primary lipophilic emulsifier and sodium caseinate as secondary hydrophilic emulsifier, we have investigated the extent to which the Span 80 can be successfully replaced by faba bean protein ( Vicia faba var. minor) encapsulated in the inner phase. Multiple emulsion stability was assessed by monitoring the amount of dye marker entrapped in the internal aqueous phase, for both fresh emulsions and those stored for 7 days at 25°C. Experiments were carried out with various samples of the protein: unmodified total protein, acetylated fractions, and fractions enriched in the 7S and 11S globulins. We conclude that encapsulation of unmodified faba bean protein does confer marginally enhanced stability on a W/O/W emulsion when the Span 80 content is substantially reduced. However, an increasing quantity of protein, as well as an increasing degree of acetylation, lowers the stability. When compared with total faba bean protein, the 11S and 7S enriched fractions were found to have different influences on the stability.