14C-8 |
Studies on the Activity of Electrolized Oxidizing Water on Conidia of Penicillium expansum |
D. O. OKULL1, A. Demirci2, and L. F. LaBorde1. (1) Dept. of Food Science, Pennsylvania State Univ., 111 Borland Lab., University Park, PA 16802-2504, (2) Dept. of Agricultural & Biological Engineering, Pennsylvania State Univ., 249 Agricultural Engineering Bldg., University Park, PA 16802 Penicillium expansum is a problem microorganism in apple and apple processing establishments because it causes economic losses due to spoilage. It is also a food safety hazard due to production of the mycotoxin, patulin. Electrolized-oxidizing (EO) water has previously been shown to be lethal to a variety of bacteria and fungi, but no studies have been done on its effect on Penicillium species. The objective of this study was to investigate the effect of EO water on conidia of P. expansum in suspension. 107 log cfu of P. expansum PP497A were suspended for 0-5min in acidic EO water diluted with sterile tap water to achieve oxidation-reduction-potentials (ORPs) of 850mV, 895mV, 967mV, and 1133mV, and 10.1µg/g, 33.5µg/g, 50µg/g, and 59.6µg/g of free available chlorine, respectively. The suspensions were then filtered through 0.22µm filters, washed with sterile distilled water, and serial dilutions were spread onto Potato Dextrose Agar (PDA) plates to enumerate viable conidia. Colony counts revealed significant activity of EO water against P. expansum at ORPs greater than 895mV. EO water at pH 2.7, 1133mV ORP, and 59.6µg/g free chlorine reduced viable conidia by 4-log units within 30 seconds of exposure. At pH 6.02, 895mV ORP, and 33.5µg/g of free chlorine, a reduction of 3-log units was achieved. Although the ORP in these treatments remained relatively high after an initial drop within 30 seconds, a tailing effect was observed on the inactivation kinetics after 30-second treatments. Inactivation was not enhanced by re-suspending previously treated conidia in fresh EO water at pH 2.7, 1133mV ORP, and 59.6µg/g of free chlorine. Successive treatment with alkaline and then acid EO water did not result in increased inactivation. EO water possesses significant activity against P. expansum, and may be a useful sanitizing agent in operations such as apple processing where the organism is a concern.
Session 14C, Food Microbiology: Food mycology
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