enterica on blueberries and strawberries, following UV-C treatment,
were not linear and the Weibull model better described the curves
with correlation coefficients of 0.83–0.99. Our data could also be
described by the Weibull model with the doses required to achieve
90% reduction of E. coli O157:H7 to be 18 and 29 mJ/cm2 on TSA and
SMAC, respectively (data not shown). The doses required to reduce
Salmonella population by 90% were estimated to be 17 and 22 mJ/cm2
on TSA and XLT-4, respectively.
Our present results suggest that UV-C could reduce population of
E. coli O157:H7 and Salmonella spp. by 0.9–2.5 log CFU/fruit, the two genera
of bacteria showing a similar response to UV-C. Allende et al. (2006)
reported that, in an in vitro test of various bacterial strains, E. coli, was
inhibited with a UV-C dose of 30 J m−2
, while S. Typhimurium was
among the most resistant strains, requiring a UV-C dose of 85 J m−2 to
completely inhibit growth. The effectiveness of UV-C in inactivating bacteria
depends on UV-C intensity, structure, and topography of the surface
of the food product (Gardner and Shama, 2000)