Loss of AM additives from antimicrobial films during storage

Films based on linear low-density polyethylene (LLDPE) and low-density polyethylene (LOPE) containing linalool or methylchavicol were prepared by extrusion film blowing. Film rolls of LLDPE containing linalool or methylchavicol were stored at ambient temperature for 1 year. Samples of these films were then evaluated for the amount of linalool or methylchavicol retained and for their antimicrobial (AM) activity by the agar disc diffusion assay. In addition, film rolls of LDPE-EVA (LOPE-ethylene vinyl acetate) containing linalool or methylchavicol were stored at 25 and 35 degrees C. Samples of these films were periodically collected to quantify the amount of linalool or methylchavicol retained as a function of time. For the AM LLDPE films, a decrease in additive retention was observed but there was no statistically significant difference in their AM activity against Escherichia coli at the beginning and after 1 year of storage. For the AM LDPE-EVA films, the amount of additive in the film decreased with time and the additive retention in all films tended to deviate from the theoretical first-order decay. These findings suggest that an amount of linalool or methylchavicol that is sufficient to maintain AM activity remained in the polymeric matrix after the storage period. This study confirms the potential use of polymeric films containing basil constituents as AM films for enhancing quality and safety as well as the extension of the shelf life of foods. (C) 2011 Elsevier Ltd. All rights reserved.