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Inactivation of Escherichia coli O157:H7 and Salmonella on mung beans, alfalfa,
and other seed types destined for sprout production by using an oxychloro-based
sanitizer
Journal of Food Protection Volume 69, Number 7 pp. 1571-1578(8)
01.jul.06
Kumar, M.; Hora, R.; Kostrzynska, M.; Waites, W.M.; Warriner, K.
The efficacy of a stabilized oxychloro-based food grade sanitizer to
decontaminate seeds destined for sprout production has been evaluated. By using
mung bean seeds as a model system, it was demonstrated that the sanitizer could
be used to inactivate a five-strain cocktail of Escherichia coli O157:H7 or
Salmonella introduced onto beans at 103 to 104 CFU/g. Salmonella was more
tolerant to stabilized oxychloro than was E. coli O157:H7, with sanitizer levels
of 150 and 50 ppm, respectively, being required to ensure pathogen-free sprouts.
The decontamination efficacy was also found to be dependent on treatment time (
8 h optimal) and the seed-to-sanitizer ratio ( 1:4 optimal). Stabilized
oxychloro treatment did not exhibit phytotoxic effects, as germination and
sprout yields were not significantly (P 0.05) different as compared with
untreated controls. Although human pathogens could be effectively eliminated
from mung beans, the aerobic plate count of native microflora on sprouts grown
from treated seed was not significantly (P 0.05) different from the controls.
The diversity of microbial populations (determined through 16S rRNA denaturing
gradient gel electrophoresis analysis) associated with bean sprouts was not
significantly affected by the sanitizer treatment. However, it was noted that
Klebsiella and Herbasprillum (both common plant endophytes) were absent in
sprouts derived from decontaminated seed but were present in control sprouts.
When a further range of seed types was evaluated, it was found that alfalfa,
cress, flax, and soybean could be decontaminated with the stabilized oxychloro
sanitizer. However, the decontamination efficacy with other seed types was less
consistent. It appears that the rate of seed germination and putative activity
of sanitizer sequestering system(s), in addition to other factors, may limit the
efficacy of the decontamination method.
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