Antimicrobial films based on pectin and sodium caseinate for the release of antifungal natamycin

The purpose of the present study was to investigate the effect of increasing sodium caseinate (CAS) of low methoxyl pectin (LMP) based-film formulations as well as pH on the release kinetics of incorporated natamycin (45mg/L of film-forming suspension) and the antimicrobial activity of films against two fungal strains. The diffusion coefficient values of natamycin from composite films to imidazole-acetate buffer (pH 7.0) were shown to depend on both protein/polysaccharide ratio and pH of formed films. Diffusion agar tests showed that films containing natamycin were more effective in inhibiting the growth of Penicillium chrysogenum than Aspergillus brasiliensis incubated at 30 degrees C during 4days. Also, active films were able to reduce the growth of P. chrysogenum voluntarily inoculated on a cured meat model with the highest spore count reduction obtained for composite film with CAS/LMP ratio of 1.00 prepared at pH 3.0. Practical applicationsNatamycin has been safely used as a natural mold inhibitor for the surface treatment of cheese, meat, and other food products due to its low solubility in water and most organic solvents. The application of natamycin in some food products can prevent the production of mycotoxins produced by molds which are known to be harmful for human health. However, the antifungal effects of natamycin can be lowered in the case of direct application in the food matrix. Thus, incorporation of natamycin in various protein/polysaccharide-based films has been investigated as an alternative in order to reduce the disadvantages of its direct addition into food products. The controlled release of antifungal agent from the film plays an important role in the surface treatment of food.