Bio-mimetic approach to improving emulsion stability: Cross-linking adsorbed beet pectin layers using laccase

The purpose of this study was to prepare and characterize stable oil-in-water emulsions containing oil droplets coated by multilayered biopolymer interfaces that were cross-linked by the enzyme laccase. Laccase is an enzyme that can cross-link ferulic acid groups present in beet pectin. Emulsions were prepared that contained 0.1 wt% corn oil, 0.05 wt% beta-lactoglobulin, and 0.02 wt% beet pectin at pH 7. The emulsions were then adjusted to pH 4.5 to promote electrostatic deposition of the beet pectin molecules onto the surfaces of the protein-coated droplets. Laccase was then added to the emulsions to promote cross-linking of the adsorbed beet pectin molecules. We have shown that stable emulsions can be formed that are coated by cross-linked beta-lactoglobulin-beet pectin interfaces, and that these emulsions have improved stability to NaCl addition over conventional one-layer or non-cross-linked two-layer emulsions. (C) 2007 Elsevier Ltd. All rights reserved.