Impact of Heat and Laccase on the pH and Freeze-Thaw Stability of Oil-in-Water Emulsions Stabilized by Adsorbed Biopolymer Nanoparticles
- Publication Type
- Journal contribution (peer reviewed)
- Authors
- Zeeb, B., Salminen, H., Fischer, L., Weiss, J.
- Year of publication
- 2014
- Published in
- Food Biophysics
- DOI
- 10.1007/s11483-013-9325-0
- Page (from - to)
- pp. 1-13
The enzymatic cross-linking of adsorbed biopolymer nanoparticles formed between whey protein isolate (WPI) and sugar beet pectin using the complex coacervation methodwas investigated. A sequential electrostatic depositioning process was used to prepare emulsions containing oil dropletsstabilized by WPI–nanoparticle–membranes. Firstly, afinely dispersed primary emulsion (10 % w/w miglyol oil,1 % w/w WPI, 10 mM acetate buffer at pH 4) was producedusing a high-pressure homogenizer. Secondly, a series ofbiopolymer particles were formed by mixing WPI (0.5 %w/w) and pectin (0.25 % w/w) solutions with subsequentheating above the thermal denaturation temperature (85 °C,20 min) to prepare dispersions containing particles in thesubmicron range. Thirdly, nanoparticle-covered emulsionswere formed by diluting the primary emulsion into coacervatesolutions (0–0.675 % w/w) to coat the droplets. Oil droplets ofstable emulsions with different interfacial membrane compo-sitions were subjected to enzymatic cross-linking. We used cross-linked multilayered emulsions as a comparison. The pH-stability of primary emulsions, biopolymer complexes and nanoparticle-coated base emulsions, as well as multilayeredemulsions, was determined before and after enzyme addition. Freeze-thaw stability (−9 °C for 22 h, 25 °C for 2 h) ofnanoparticle-coated emulsions was not affected by laccase. Results indicated that cross-linking occurred exclusively inthe multilamellar layersand not between adsorbed biopolymernanoparticles. Results suggest that the accessibility of distinctstructures may play a key role for biopolymer-cross-linkingenzymes.