The effects of coating structure and water-holding capacity on the oxygen-scavenging capacity of enzymes embedded in the coating layer

摘要

Oxygen-scavenging enzymes were embedded in latex-based coatings with and without barrier kaolin clay in order to produce material for active packages. The clay was used in order to create a porous structure and the closed structure contained either starch or gelatin to increase the water uptake of the coating. The effects of the porous open structure and of the water uptake of the coated layer on the oxygen-scavenging ability of the embedded enzymes were examined at both 75% RH and 100% RH. The results showed that the porous clay structure led to a higher oxygen-scavenging capacity than that of a closed structure at both test conditions, by enabling a high diffusion rate for oxygen and glucose to the active sites of the enzymes. The addition of a water-holding biopolymer did not always significantly affect the oxygen-scavenging capacity. However in a closed layer at 100 % RH, an increase in the amount of biopolymer resulted in an increase in oxygen-scavenging capacity. The coatings were also characterized with respect to water vapor uptake, overall migration, porosity, and SEM images.