Chloroxyanion residue on seeds and sprouts after chlorine dioxide sanitation of alfalfa seed

Authors: Smith, David; Herges, Grant

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2018
Publication Date: 2/28/2018
Publication URL: http://handle.nal.usda.gov/10113/5927838
Citation: Smith, D.J., Herges, G.R. 2018. Chloroxyanion residue on seeds and sprouts after chlorine dioxide sanitation of alfalfa seed. Journal of Agricultural and Food Chemistry. 66(8):1974-1980. https://doi.org/10.1021/acs.jafc.7b05953.

Interpretive Summary: Pathogenic bacteria, if present on seeds used to produce sprouts for human food, can proliferate greatly during the sprout-making process. Unfortunately, there are no technologies that are completely effective at eliminating pathogens present on seeds before, during, or after the sprouting process. Chlorine dioxide gas is very effective at eliminating pathogens from a variety of fruits, vegetables, melons, seeds, and food preparation surfaces. The gaseous form of chlorine dioxide, however, has not been approved by regulatory authorities for use on human foods. Data generated by this study show that even when high concentrations of chlorine dioxide gas are used to treat alfalfa seed, undesirable chemical residues are not present in edible sprouts grown from those seeds. The study suggests that chemical residues are not a major obstacle for the development of chlorine dioxide gas as safe treatment for edible sprout production.

Technical Abstract: The effects of a 6-h chlorine dioxide sanitation of alfalfa seed (0, 50, 100, and 200 mg/kg seed) on total coliform bacteria, seed germination, and on the presence of chlorate and perchlorate residues in seed rinse, seed soak, and in alfalfa sprouts was determined. Chlorate residues in 20000 ppm calcium hypochlorite, commonly used to disinfect seed, were quantified. Chlorine dioxide treatment reduced (P < 0.05) total coliforms on seeds with no effect (P > 0.05) on germination. Dose-dependent sodium chlorate residues were present in seed rinse (4.1 to 31.2 µg/g seed) and soak (0.7 to 8.3 µg/g seed) waters, whereas chlorate residues were absent (LOQ 5 ng/g) in sprouts, except for 2 of 5 replicates from the high chlorine dioxide treatment. Copious chlorate residues were present (168 to 1260 mg/L) in freshly prepared 20,000 ppm calcium hypochlorite solution and storage at room temperature increased chlorate residues significantly (P < 0.01).