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UV-C inactivation of Escherichia coli and dose uniformity on apricot fruit in a commercial setting

Ruixiang Yan, James Mattheis, Joshua Gurtler, Joseph Sites, Xuetong Fan
Postharvest biology and technology 2014 v.95 pp. 46-49
bacterial contamination, fruits, decontamination, total soluble solids, food contamination, food irradiation, food processing, fruit quality, firmness, titratable acidity, color, Escherichia coli O157, ultraviolet radiation, apricots, bacteria, antibacterial properties
A UV-C treatment system (two treatment chambers connected by an inclined belt to rotate apricots between chambers) was tested in a commercial setting. Escherichia coli ATCC 25922, used as a surrogate for E. coli O157:H7 to determine the system's antimicrobial efficacy, was inoculated onto fruit surfaces at a population of 6.8log CFU/fruit. UV-C dosage was evaluated by attaching film dosimeters to six fixed locations on each apricot. Results suggested that reduction of inoculated E. coli ATCC 25922 populations on the apricot fruit by UV-C treatment was small (only 0.5–0.7logs). There were large variations in UV-C doses among varying apricot surface locations. Approximately 1/3 of apricots had individual surfaces receiving less than 0.2kJm−2 UV-C exposure, even though fruit received, on average, more than 1kJm−2. Low reductions of E. coli may be attributed, in part, to non-uniform UV-C exposure. This study demonstrates the need to use a fruit rotation device more capable of delivering uniform UV-C dosage to the surface of apricots for inactivating bacteria in a commercial setting.