100B-24 |
Release of nisin from nisin-coated low-density polyethylene (LDPE) films in solution |
J. L. GROWER1, D. K. Cooksey1, and K. Getty2. (1) Department of Packaging Science, Clemson University, B212 P & A Building, Box 340370, Clemson, SC 29634, (2) Food Science Institute, Kansas State University, 148 Waters Hall, Manhattan, KS 66506 Packaging film coated with a nisin-containing coating may reduce Listeria monocytogenes (LM) outgrowth on the surface of food products by release of nisin over time. The objective was to determine the effect of nisin-containing cellulose-based coating on the release of nisin in solution. LDPE films were coated with either high or low viscosity cellulose derivatives, methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC). Two sets of films with different viscosities of MC and HPMC were made. The high variable (H) was made with high viscosity MC and HPMC. The low variable (L) was made with low viscosity MC and HPMC. All films contained 2,500; 5,000; 7,500; 10,000 IU/cm2 nisin or no nisin (control). Film samples were individually placed into sterile peptone water and held for 1, 30, 60 min.; 8, 24 hours; 4 and 8 days at ambient temperatures. A 10mL drop of solution was placed onto tryptic soy agar plates inoculated with LM (approximate populations of 5.62 log CFU/cm2). Plates were incubated (37ºC, 48h) and zones of inhibition were measured (mm). Experiments were performed in triplicate. There were no significant differences (p>0.05) for zones of inhibition between low viscosity cellulose coatings and high viscosity cellulose coatings. Larger zones of inhibition were observed for films containing higher levels of nisin. No zones of inhibition were observed for 2,500 IU/cm2 L and H viscosities at all time intervals. At 1, 30, 60 min. and 8 days, 5,000; 7,500; and 10,000 IU/cm2 L and H viscosities produced zones of inhibition. At 8h, 7,500; and 10,000 IU/cm2 L and H viscosities exhibited zones of inhibition. For all treatments, at 24h and 4 days no zones of inhibition were observed. The initial and delayed release of nisin from both cellulose-based coating variables over time may effectively inhibit the growth of surface bacteria when the coated films are used in a food application.
Session 100B, Food Packaging
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