Microbial contamination in sprouts: how effective is seed disinfection treatment?

Microbial contamination of sprouts by Salmonella and Escherichia coli O157 : H7 has been a common cause of foodborne diseases and a continuing challenge to the sprout industry. Seed disinfection treatment has been recommended as a major intervention step in a multihurdle approach to reduce the risk of illness associated with contaminated sprouts. U.S. Food and Drug Administration cited 20000 ppm calcium hypochlorite as an example treatment in its recommendation for seed treatment and this treatment has been considered the reference standard for seed disinfection treatment for over a decade. However, promising new disinfection treatments have emerged in recent years. In this study, we summarized published data and compared the efficacies of different disinfection methods in the reduction of microbial contamination on seeds. Our findings suggest that while biological interventions such as competitive exclusion and certain chemical treatments appear to be similar to 20000 ppm calcium hypochlorite for seed disinfection, physical methods especially high pressure may be more effective than the reference standard regardless of the type of bacteria or seed. The combination of 2 or more treatments, sequentially or simultaneously, may further improve disinfection results. Since treatments with high levels of chemical disinfectants, especially 20000 ppm calcium hypochlorite, can pose environmental and worker safety risks, alternative intervention approaches should be considered. Additional studies to confirm the greater efficacy of certain physical and combined seed disinfection treatments and to identify other effective management strategies are needed to further improve sprout safety.