|
ISS
820 East 20th Street
Cookeville, TN 38501 USA
931 526 1106
Bob@sproutnet.com
中文版
En espaņol
| |
Potential application of high hydrostatic pressure to eliminate Escherichia coli
O157:H7 on alfalfa sprouted seeds
International Journal of Food Microbiology, Volume 128, Issue 2, 10 December
2008, Pages 348-353, Hudaa Neetoo, Mu Ye, Haiqiang Chen ,Department of Animal
and Food Sciences, University of Delaware, Newark, DE 19716-2150, USA
Abstract
Sprouts eaten raw are increasingly being perceived as hazardous foods as they
have been implicated in Escherichia coli O157:H7 outbreaks where the seeds were
found to be the likely source of contamination. The objective of our study was
to evaluate the potential of using high hydrostatic pressure (HHP) technology
for alfalfa seed decontamination. Alfalfa seeds inoculated with a cocktail of
five strains of E. coli O157:H7 were subjected to pressures of 500 and 600 MPa
for 2 min at 20 °C in a dry or wet (immersed in water) state. Immersing seeds in
water during pressurization considerably enhanced inactivation of E. coli
O157:H7 achieving reductions of 3.5 log and 5.7 log at 500 and 600 MPa,
respectively. When dry seeds were pressurized, both pressure levels reduced the
counts by < 0.7 log. To test the efficacy of HHP to completely decontaminate
seeds whilst meeting the FDA requirement of 5 log reductions, seeds inoculated
with a ~ 5 log CFU/g of E. coli O157:H7 were pressure-treated at 600 and 650 MPa
at 20 °C for holding times of 2 to 20 min. A > 5 log reduction in the population
was achieved when 600 MPa was applied for durations of ≥ 6 min although
survivors were still detected by enrichment. When the pressure was stepped up to
650 MPa, the threshold time required to achieve complete elimination was 15 min.
Un-inoculated seeds pressure-treated at 650 MPa for 15 min at 20 °C successfully
sprouted achieving a germination rate identical to untreated seeds after eight
days of sprouting. These results therefore demonstrate the promising application
of HHP on alfalfa seeds to eliminate the risk of E. coli O157:H7 infections
associated with consumption of raw alfalfa sprouts.
|
