Efficacy of chemical treatments in eliminating Salmonella and Escherichia coli O157 : H7 on scarified and polished alfalfa seeds

Alfalfa seeds are sometimes subjected to a scarification treatment to enhan ce water uptake, which results in more rapid and uniform germination during sprout production. It has been hypothesized that this mechanical abrasion treatment diminishes the efficacy of chemical treatments used to kill or re move pathogenic bacteria from seeds. A study was done to compare the effect iveness of chlorine (20,000 ppm), H2O2 (8%), Ca(OH)(2) (1%), Ca(OH)(2) (1%) plus Tween 80 (1%), and Ca(OH)(2) (1%) plus Span 20 (1%) treatments in kil ling Salmonella and Escherichia coli O157:H7 inoculated onto control, scari fied, and polished alfalfa seeds obtained from two suppliers. The influence of the presence of organic material in the inoculum carrier on the efficac y of sanitizers was investigated. Overall, treatment with 1% Ca(OH)(2) was the most effective in reducing populations of the pathogens. Reduction in p opulations of pathogens on seeds obtained from supplier I indicate that che mical treatments are less efficacious in eliminating the pathogens on scari fied seeds compared to control seeds. However, the effectiveness of chemica l treatment in removing Salmonella and E. coli O157:H7 from seeds obtained from supplier 2 was not markedly affected by scarification or polishing. Th e presence of organic material in the inoculum carrier did not have a marke d influence on the efficacy of chemicals in reducing populations of test pa thogens. Additional lots of control, scarified, and polished alfalfa seeds of additional varieties need to be tested before conclusions can be drawn c oncerning the impact of mechanical abrasion on the efficacy of chemical tre atment in removing or killing Salmonella and E. coli O157:H7.