Effect of surface-active stabilizers on the microstructure and stability of coconut milk emulsions

Abstract

The effect of homogenization and surface-active stabilizers (0–1 wt% sodium caseinate, whey protein isolate, sodium dodecyl sulfate, or polyoxyethylene sorbitan monolaurate) on the microstructure and colloidal stability of coconut milk was determined using measurements of particle size and creaming, as well as microscopy. The freshly prepared coconut milk emulsions (1.8–2% protein, 17–18% fat) had large ( d 43∼10 μm) but non-flocculated droplets. Homogenization reduced the primary droplet size but induced flocculation. Adding small-molecule surfactants after the homogenization step can displace coconut proteins from the interface and break up these flocs, but adding them before homogenization increased the efficiency of the homogenization step and produced stable, submicron-sized emulsion droplets. Adding protein stabilizers did not break up the flocs of coconut milk droplets when added after homogenization, but did increase the efficacy of the homogenization step when added prior to it. Adding stabilizers to non-homogenized coconut milk had no effect on the structure or properties of the emulsions.