The possibility to use enzymes as oxygen scavengers embedded in latex/ TiO2 dispersion coatings was demonstrated in a series of experiment where different grades of paperboard were coated. Simple draw-down coatings were used as application method.
The enzyme system consisted of glucose oxidase in combination with an enzyme that removes peroxides (peroxidase/catalase). Glucose or glucose derivatives were used as substrates for the enzymatic reaction. The enzyme-containing coatings seemed to persist drying at elevated temperatures for limited period of times. The period of time with no dramatic decrease in enzyme activity was substantial shorter than drying times in real industrial coating and printing processes (on condition that the web will be cooled down before reeling up). The coatings could also be stored in air at room temperature for long period of times without any
loss in enzyme activity.
Oxygen absorption tests and rancidity tests revealed that an activation of the coated sheets with liquid water was needed in order to initiate the oxygen scavenging processes. The oxygen absorption tests showed that activated enzyme-containing coatings were able to decrease the oxygen level dramatically, also for a very high start concentration of oxygen (8.8% and atmosphere oxygen).
The rancidity tests showed that minced ham can be kept at room temperature for extended period of times without any detectable onset of oxidation when packed in model packages containing enzyme-containing sheets, compared to reference packages without enzymes. However all rancidity tests were not consistent with this observation: Tests with an oatmeal “sponge cake” indicated no effects of the enzymes. The results clearly indicate that positive effects of the enzyme coatings did exist but further research is needed in order to understand the limitations with respect to end-use applications. Further research is also needed to enhance the window where the concept has the desired capacity to reduce oxygen concentration and prevent oxidative processes.
Project duration: May 2006 - Jaunary 2008