Antimicrobial films based on cellulose-derived hydrocolloids. A synergetic effect of host-guest interactions on quality and functionality.

A series of active films based on biodegradable cellulose-derived hydrocolloids capable of controlled release of antimicrobial propionic acid (PA) was prepared. β-Cyclodextrin (β-CD), usually used for encapsulation of lipophilic compounds, was utilized in this research to host the hydrophilic PA. It was found that addition of β-CD to the film forming solutions notably enhanced the hydrocolloid matrix capacity and resulted in up to a ten-fold increase in the amount of uploaded PA. In addition, β-CD resulted in a two-fold prolongation of the effective PA release duration. β-CD alone caused undesired effects on the physical, mechanical and morphological properties of the hydrocolloid films. Interestingly, when β-CD was combined with PA in the film formulation, its undesired effects were significantly subdued. The antifungal activity of the films was demonstrated on fresh harvested wheat grains. Films containing β-CD and PA were found to be effective in preventing fungal growth on wheat grains. Thus, incorporation of β-CD and PA in hydrocolloids matrices demonstrated a synergetic effect and resulted in the formation of biodegradable active films that benefit good physical and mechanical properties, high active agent content, prolonged release ability and effective antimicrobial properties.