Double emulsions stabilized by a charged complex of modified pectin and whey protein isolate
Rachel Lutza¹, Abraham Aserina¹, Louis Wickerb², Nissim Gartia¹; IN PRESS Colloids and Surfaces B: Biointerfaces
Abstract: Double emulsions based on naturally occurring stabilizers for food applications were studied. Two charged biopolymers, whey protein isolate (WPI) and enzymatic modified pectins, interacted in aqueous solution to form a charge–charge complex that was utilized as a hydrophilic polymeric steric stabilizer improving the double emulsion stability. The main factors that influence the interaction between protein and pectin were investigated in relation to double emulsion stability: creaming, coalescence, and water transport between aqueous phases. The pH determined the size of the complex formed. Thus at pH 6, where a soluble complex was obtained between some molecular positively charged patches on the protein and negatively charged fractions of the hydrocolloids, the double emulsionwas the most stable. With the smallest droplet size (ca. 15μm), the lowest creaming, highest yield, and minimized water transport were obtained. The best concentration and ratio to form the soluble complex are 4 wt% WPI and 0.5 wt% pectin (for 30 wt% of the W/O inner phase). The influence of the charge distribution (degree of order of the carboxylic groups) of the pectin on the associated complex was also investigated, and it was found that the more “ordered” pectin (U63) formed the most stable double emulsion against water transport.
Key words: Emulsion stability • Double emulsion • Whey protein isolate WPI • Modified pectin • Multiple emulsions • Water transport • LUMiFuge
¹ Casali Institute of Applied Chemistry, The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel; ²Department of Food Science and Technology, University of Georgia, Athens, GA 30602-7610, USA.Contact us
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