Disinfection of alfalfa and radish sprouting seed using oxidizing agents and treatments compliant with organic food production principles.

Antimicrobial seed treatments recommended by Canadian guidance for sprouted vegetable production (2,000 ppm hypochlorite for 15-20 minutes or 6-10% hydrogen peroxide for 10 minutes at room temperature) are not fully compliant with organic production principles. We investigated the effect of a sequential treatment consisting of a 10 min soak at 50 0 C in water followed by exposure to a 2.0% H 2 O 2 + 0.1% AcOH sanitizing solution against E. coli O157:H7, L. monocytogenes and S. enterica inoculated onto alfalfa and radish seed. The sequential treatment was as effective as the recommended treatments and could reduce populations of all three species by a minimum of 3 log cfu g -1 using a reduced (1:2) ratio of seed to sanitizing solution and low concentrations of sanitizers approved for use in organic food production. However, the efficacy of all the treatments examined in this work was considerably reduced by storage of the seed for 4 weeks at either 11 or 75% relative humidity prior to treatment and assessment. None of the treatments could eradicate the target pathogens from seed, irrespective of time elapsed since inoculation. The results of this work suggest that the effect of storage should be considered in the assessment of antimicrobial treatments for sprouting vegetable seed.