TitleAntimicrobial chitosan-lysozyme (CL) films and coatings for enhancing microbial safety of mozzarella cheese.
Publication TypeJournal Article
Year of Publication2007
AuthorsDuan, J, Park, S-I, Daeschel, MA, Zhao, Y
JournalJ Food Sci
Volume72
Issue9
PaginationM355-62
Date Published2007 Nov
ISSN1750-3841
KeywordsAnalysis of Variance, Anti-Infective Agents, Bacteria, Cheese, Chitosan, Colony Count, Microbial, Escherichia coli, Food Contamination, Food Handling, Food Microbiology, Food Packaging, Fungi, Hydrogen-Ion Concentration, Listeria monocytogenes, Membranes, Artificial, Muramidase, Pseudomonas fluorescens, Yeasts
Abstract

This study investigated the antimicrobial activities of chitosan-lysozyme (CL) composite films and coatings against tested microorganisms inoculated onto the surface of Mozzarella cheese. CL film-forming solutions (FFS) with a pH of 4.4 to 4.5 were prepared by incorporating 0% or 60% lysozyme (per dry weight of chitosan) into chitosan FFS with or without a pH adjustment to 5.2. Sliced cheese was subjected to 3 CL package applications: film, lamination on a multilayer coextruded film, and coating. Cheese was inoculated with Listeria monocytogenes, Escherichia coli, or Pseudomonas fluorescens at 10(4) CFU/g, or with mold and yeast at 10(2) CFU/g. Inoculated cheese was individually vacuum packaged and stored at 10 degrees C for sampling at 1, 7, and 14 d for bacteria, and at 10, 20, and 30 d for fungi. Inoculated bacteria survived but failed to multiply in untreated cheese during storage. Treated cheese received 0.43- to 1.25-, 0.40- to 1.40-, and 0.32- to 1.35-log reductions in E. coli, P. fluorescens, and L. monocytogenes, respectively. Incorporation of 60% lysozyme in chitosan FFS showed greater antimicrobial effect than chitosan alone on P. fluorescens and L. monocytogenes. The pH adjustment only affected the antimicrobial activity on L. monocytogenes, with lower pH (unadjusted) showing greater antimicrobial effect than pH 5.2. Mold and yeast increased to 10(5) CFU/g in untreated cheese after 30 d storage. Growth of mold was completely inhibited in cheese packaged with CL films, while 0.24- to 1.90- and 0.06- to 0.50-log reductions in mold populations were observed in cheese packaged with CL-laminated films and coatings, respectively. All CL packaging applications resulted in 0.01- to 0.64-log reduction in yeast populations.

DOI10.1111/j.1750-3841.2007.00556.x
Alternate JournalJ. Food Sci.
PubMed ID18034728