Antimicrobial Chitosan‐Lysozyme (CL) Films and Coatings for Enhancing Microbial Safety of Mozzarella Cheese

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.

Development of flexible zein–wax composite and zein–fatty acid blend films for controlled release of lysozyme

“…However, due to their protective outer membrane surrounding the peptidoglycan layer, it does not show antibacterial activity against Gram-negative bacteria. Thus, the application of lysozyme in active packaging targets mainly inhibition of the critical Gram-positive pathogenic bacteria such as Listeria monocytogenes (Duan, Park, Daeschel, & Zhao, 2007;Min, Harris, Han, & Krochta, 2005). However, when lysozyme is combined with ethylenediaminetetraacetic acid (EDTA), the outer membranes of Gram-negative bacteria are destabilized by EDTA and the obtained films become effective on the other critical pathogenic bacteria including Escherichia coli O157:H7 and Salmonella typhimurium (Gucbilmez, Yemenicioglu, & Arslanoglu, 2007;Mecitoglu et al, 2006;Padgett, Han, & Dawson, 1998;Ünalan et al, 2011).…”

Development of activate-at-home-type edible antimicrobial films: An example pH-triggering mechanism formed for smoked salmon slices using lysozyme in whey protein films

“…Thus, the application of LYS in active packaging targets mainly the inhibition of critical Gram-positive pathogenic bacteria such as Listeria monocytogenes (Duan, Park, Daeschel, & Zhao, 2007). The prevention of food contamination by L. monocytogenes, and application of hurdles to prevent listerial growth in risky food are critically important since this bacterium may cause deadly infections ( Alvarez-Ord oñez, Leong, Hickey, Beaufort, & Jordan, 2015).…”

The Antimicrobial Activity of Chitosan and Its Application on Kariesh Cheese Shelf Life

“…The treatment of cheese with Chitosan lead to the inhibition and retardation of molds and yeasts growth and lowered the maximum growth levels in the cheese, as mentioned by (Sagoo, et al, 2002), they reported a similar sensitivity to Chitosan for yeasts and molds; they concluded that the yeasts and molds counts in sausage dipped in 1.0% Chitosan were reduced approximately by 2 log CFU /g at the end of 18 storage days at 4 o C. Also, Duan et al, (2007) mentioned yeast and mold increased to 10 5 CFU/g in untreated Mozzarella cheese after 30 d storage. Bostan and Mahan, (2011) revealed that yeast and mold counts in sausage treated with Chitosan during cold storage were considerably lower than non-treated sausage at all sampling days.…”