Purpose: Evaluate the efficacy of three organic sanitizers, acidified sodium chlorite (ASC, also known as Sanova), stabilized oxychloro-based sanitizer (SOC, also known as Germin-8-or), and the organic CHICO wash, in comparison with 20,000 ppm Ca(OCl)2 for disinfection of alfalfa seeds artificially inoculated with Salmonella. Small-scale experiments were conducted to determine the best treatment conditions. Large-scale studies were performed to evaluate the commercial applicability of these sanitizers.
Methods: Ten g of seeds inoculated with 3-4 log CFU/g of S. Typhimurium expressing green fluorescent protein was treated with different concentrations of ASC, SOC, and the CHICO wash for different periods of time. For large-scale runs, 1 kg of seeds spiked with 1 % (w/w) of inoculated seeds was treated with each sanitizer under optimal treatment conditions. As a comparison, seeds were also treated with 20,000 ppm Ca(OCl)2 for 15 min. After treatments, seeds were rinsed twice with sterile tap water and analyzed for Salmonella by plate counts or the 3-tube MPN method.
Results: The efficacy of ASC and SOC increased with increasing concentrations (up to 1500 ppm) and treatment time (up to 24h); however, the germination rates for seeds treated with > 1200 ppm of either sanitizer were < 80%. Treatment with 800 ppm of ASC or SOC for 3h reduced the Salmonella level, respectively, by 2.3 logs or > 2 logs to an undetectable level, compared with the ~1 log decrease observed in seeds treated with 20,000 pm Ca(OCl)2. Treatment with 15% (v/v) CHICO wash for 10 min lowered the germination rate to 73% but only reduced the Salmonella count by 0.9 log. For the large-scale runs, the Salmonella level in seeds treated with 800 ppm SOC for 3h decreased by > 1.9 log to an undetectable level (< -2.52 log MPN/g) compared with a 1.5 log reduction in seeds treated with 20,000 ppm Ca(OCl)2.
Significance: The stabilized oxychloro-based sanitizer may provide an alternative seed treatment method for organic sprout growers.