Association between lysozyme and carboxymethyl konjac glucomannan to produce dispersible coacervates for edible coating

Abstract

Lysozyme was subjected to coacervate with carboxymethyl konjac glucomannan (CMKGM) to check if dispersible coacervates could be formed to extend its application in edible coatings. The results indicated that complex coacervation could occur between lysozyme and CMKGM only within a narrow pH range from pH 2.5 to 6.0 and the maximum interaction was recorded in a moderate temperature of 35 °C in the absence of NaCl. The dispersion status of the lysozyme – CMKGM coacervates was closely related to the phase separation pH as well as lysozyme to CMKGM mixing ratio and conditions that led to the presence of free CMKGM in the solution favored the formation of dispersible coacervates. Rheological measurements revealed the high viscosity of CMKGM solution contributed greatly to the dispersion status of the lysozyme – CMKGM coacervates. Coacervation with CMKGM caused structural changes to lysozyme, but only slightly affected its lytic activity. Contact angle measurement revealed that the lysozyme – CMKGM coacervates were more hydrophobic than the two single polyelectrolytes. Hence, the dispersible lysozyme – CMKGM coacervates were potential in the fabrication of composite antibacterial edible coatings.