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Fate of E. coli O157:H7, Salmonella spp. and potential surrogate bacteria on apricot fruit, following exposure to UV-C light.

Authors :
Yun J
Yan R
Fan X
Gurtler J
Phillips J
Source :
International journal of food microbiology [Int J Food Microbiol] 2013 Sep 16; Vol. 166 (3), pp. 356-63. Date of Electronic Publication: 2013 Aug 03.
Publication Year :
2013

Abstract

Some soft fruit, such as tree-ripened apricots, cannot be washed with aqueous sanitizers, due to their innate softness and delicate surfaces. In this study, ultraviolet-C (UV-C) light was investigated for its efficacy in inactivating 4-5 individual strains of Escherichia coli O157:H7 and Salmonella spp. on apricots, in addition to a four-strain composite of Shiga toxin-negative E. coli O157:H7 and a cocktail of three attenuated strains of Salmonella Typhimurium and Salmonella Typhimurium LT2. Also, the survival of E. coli O157:H7 and Salmonella spp. after exposure to 74 and 442 mJ/cm² of UV-C was evaluated during post-UV storage at 2 and 20 °C. The fruit was spot inoculated and the areas (ca. 1.5 cm²) of fruit surface with the inoculated bacteria were exposed to UV-C at 7.4 mW/cm². E. coli O157:H7 and Salmonella spp. populations decreased rapidly (1-2 logs) (P<0.05) with increasing UV-C doses of 0 to 74 mJ/cm². Further increases in UV-C dosage achieved only limited additional reductions in bacterial populations. Shiga toxin-negative bacteria and attenuated S. Typhimurium strains, along with S. Typhimurium LT2, responded similarly to corresponding pathogenic E. coli O157:H7 and Salmonella spp. During storage at 2 or 20 °C, populations of pathogenic E. coli O157:H7 and Salmonella spp. on untreated fruit decreased slowly; however, populations on fruit treated with 442 mJ/cm² decreased rapidly at both temperatures. After 8 days at 20 °C or 21 days at 2 °C, E. coli O157:H7 and Salmonella spp. populations on UV-C treated fruit were at least 2 log CFU/g lower than on non-treated controls. Our results suggest that surface-inoculated bacteria survived poorly following UV-C treatment of apricots.<br /> (© 2013 Elsevier B.V. All rights reserved.)

Details

Language :
English
ISSN :
1879-3460
Volume :
166
Issue :
3
Database :
MEDLINE
Journal :
International journal of food microbiology
Publication Type :
Academic Journal
Accession number :
24021820
Full Text :
https://doi.org/10.1016/j.ijfoodmicro.2013.07.021