100B-1 |
Antimicrobial, mechanical and barrier properties of polyvinylidene chloride food packaging films containing sorbic acid, potassium sorbate or nisin |
P. LIMJAROEN1, B. Harte1, H. E. Lockhart1, and E. T. Ryser2. (1) School of Packaging, Michigan State University, 130 Packaging Building, East Lansing, MI 48824, (2) Department of Food Science and Human Nutrition, Michigan State University, 2108 S. Anthony Hall, East Lansing, MI 48824 Listeria monocytogenes - a serious psychrotrophic foodborne pathogen found in food-processing environments and home refrigerators, remains the major cause of microbiologially-related Class I recalls of ready-to-eat foods with this pathogen entering foods as a post-processing contaminant. The objective of this study was to develop an antilisterial food packaging film from polyvinylidene chloride that could be used as a food wrap by home consumers. Polyvinylidene chloride (Saran F-310) food packaging films containing sorbic acid, potassium sorbate or nisin were formed by a solvent-casting method using methyl ethyl ketone as the solvent. Polyvinylidene chloride film solutions were adjusted to pH 5.2 using 1.0 N lactic acid after incorporating 0.5-3% (w/v) sorbic acid, potassium sorbate or nisin, cast in petri plates and dried at 85°C for 5 minutes. Films were tested for antimicrobial activity against Listeria monocytogenes on trypticase soy agar (pH 5.2) containing 0.6% yeast extract acidified using a modified disc diffusion assay. Inhibition zone diameters were measured following 48 h of incubation at 35oC. Film thickness, water vapor permeability, oxygen permeability, tensile strength and 3-dimensional structure by scanning electron microscopy were also determined according to ASTM standards. Films containing ³ 1.0% nisin, ³ 1.5% sorbic acid or ³ 2.0% potassium sorbate produced inhibition zones for all Listeria monocytogenes strains tested. Films containing 1.5%, 2% and 3% sorbic acid were most inhibitory, producing inhibition zones of 24.8, 29.0 and 32.8 mm, respectively. These films were of uniform thickness [2.5 milą 0.1] (p<.05) and homogeneous based on microscopic analysis. However, sorbic acid films exhibited significantly higher (p<.05) water vapor permeability and significantly lower (p<.05) tensile strength compared to sorbic acid-free control films. When applied as a coating to other films, our antimicrobial polyvinylidene chloride film may prove beneficial for enhancing the safety and shelf-life of ready-to-eat foods.
Session 100B, Food Packaging
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