The International Conference on Safety and Innovation in Food Packaging, which took place in Lisbon last June, presented a study on the development of chitosan and methylcellulose films with the presence of natamycin, a powerful antimicrobial agent.
The study explains how chitosan films and coatings are formed as a result of the film-forming properties of natural biopolymers, and shows the effect that a food additive like natamycin can have on them and on methylcellulose films.
To begin with, the chitosan films were dissolved in an aqueous solution containing glycerol. This was then stirred for 2 hours at 80° C, and then for 12 hours at room temperature after natamycin was added.
Meanwhile, the methylcellulose was mixed with a water-ethanol mixture and underwent a homogenisation process for 5 minutes. Glycerol was added and the solution was stirred for 2 hours at 80° C. To counteract the effect of temperature, natamycin was added to the films that were at room temperature.
After six days, the methylcellulose films contained 70% natamycin. However, the chitosan films only contained 15% of natamycin after 24 days.
The conclusion is that the chitosan films are more stable with a compact structure, which hinders the diffusion of natamycin through the matrix of the film, in stark contrast to the methylcellulose films which are often used in food packaging.