Biodegradable film development by nisin Z addition into hydroxypropylmethylcellulose matrix for mozzarella cheese preservation

Abstract

Currently, improvement of food preservation has been a substantial challenge for industries to increase shelf-life of products and to maintain food quality during storage. These goals are often tied to the sustainable tendency for use of eco-friendly packaging to store these products without loss of the packaging features. Therefore, the aim of this study was to produce biodegradable antimicrobial films by the incorporation of nisin Z peptide under different concentrations (0 %, 5 %, 10 %, 15 % and 20 % wt.) into hydroxypropylmethylcellulose (HPMC) matrices. The active film properties were evaluated in terms of their antimicrobial capacity in vitro, mechanical performance and microscopic characteristics. Hence, active films containing 10 % (wt.) of nisin Z and control films were placed in contact with sliced mozzarella cheese for eight days, and microbiological growth was monitored during storage. Nisin Z’s antimicrobial effects were observed against the Gram-positive microorganisms such as Staphylococcus aureus and Listeria innocua, regardless if the compound was free as a suspension or incorporated into HPMC matrices. However, the expected low action of nisin Z against Gram-negative bacteria, as reported in literature, was not observed since Salmonella enterica Choleraesuis’s growth was inhibited. Moreover, active films with added nisin Z (10 % wt.) were more effective than the control film to inhibit mesophilic microorganisms in mozzarella cheese during 8 days of storage. The mechanical properties of the films were not influenced by nisin Z incorporation, since the addition of the compound enhanced the active function without the loss of mechanical properties required for a good food packaging. These results suggest that biodegradable films produced by nisin Z addition into HPMC matrix are an excellent biomaterial for mozzarella cheese preservation.