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Appl. Environ. Microbiol., Jul 1996, 2212-2215, Vol 62, No. 7
CB Jaquette, LR Beuchat and BE Mahon
The efficacy of chlorine and hot water treatments in killing Salmonella
stanley inoculated onto alfalfa seeds was determined. Treatment of seeds
containing 10(2) to 10(3) CFU/g in 100-micrograms/ml active chlorine
solution for 5 or 10 min caused a significant (P < or = 0.05) reduction
in population, and treatment in 290-micrograms/ml chlorine solution
resulted in a significant reduction compared with treatment in 100
micrograms of chlorine per ml. However, concentrations of chlorine of up to
1,010 micrograms/ml failed to result in further significant reductions.
Treatment of seeds containing 10(1) to 10(2) CFU of S. stanley per g for 5
min in a solution containing 2,040 micrograms of chlorine per ml reduced
the population to undetectable levels (< 1 CFU/g). Treatment of seeds in
water for 5 or 10 min at 54 degrees C caused a significant reduction in the
S. stanley population, and treatment at > or = 57 degrees C reduced
populations to < or = 1 CFU/g. However, treatment at > or = 54
degrees C for 10 min caused a substantial reduction in viability of the
seeds. Treatment at 57 or 60 degrees C for 5 min appears to be effective in
killing S. stanley without substantially decreasing germinability of seeds.
Storage of seeds for 8 to 9 weeks at 8 and 21 degrees C resulted in
reductions in populations of S. stanley of about 1 log10 and 2 log10 CFU/g,
respectively. The behavior of S. stanley on seeds during soaking
germination, sprouting, and refrigerated storage of sprouts was determined.
An initial population of 3.29 log10 CFU/g increased slightly during 6 h of
soaking, by about 10(3) CFU/g during a 24-h germination period, and by an
additional 10 CFU/g during a 72-h sprouting stage. A population of 10(7)
CFU/g of mature alfalfa sprouts was detected throughout a subsequent 10-day
storage period at 5 degrees C. These studies indicate that while
populations of S. stanley can be greatly reduced, elimination of this
organism from alfalfa seeds may not be reliably achieved with traditional
disinfection procedures. If S. stanley is present on seeds at the
initiation of the sprout production process, populations exceeding 10(7)
CFU/g can develop and survive on mature sprouts exposed to handling
practices used in commercial production and marketing.
Copyright © 1996, American Society for Microbiology
Efficacy of chlorine and heat treatment in killing Salmonella stanley inoculated onto alfalfa seeds and growth and survival of the pathogen during sprouting and storage
Department of Food Science and Technology, University of Georgia, Griffin 30223-1797, USA.
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