Antimicrobial Packaging Materials from Poly(Lactic Acid) Incorporated with Pectin-Nisaplin® Microparticles

The thermostability of nisin and Nisaplin® was investigated in the presence and absence of pectin. By mixing with pectin, both nisin and Nisaplin® were able to inhibit microbial growth, even after heating to 433 K. In contrast, without pectin, the nisin was totally inactivated after heat treatment. Nisin and pectin in solution were complexed, as shown by atomic force microscopic analysis. Probably, the complex formation between the polysaccharide and the polypeptide improves the nisin thermostability; however, a detailed mechanism remains to be resolved. Thin membranes were prepared by co-extrusion of poly(lactic acid) and microparticles of pectin-Nisaplin®. Despite the high extrusion temperatures, the presence of pectin protected the biological activity of nisin and the resultant membranes were antimicrobial and could be used as an inner layer of multi-layer packaging materials for active packaging.