Inactivation of Escherichia coli O157:H7 and Salmonella Typhimurium DT 104 on Alfalfa Seeds by Levulinic Acid and Sodium Dodecyl Sulfate

Studies were conducted to determine the best concentration and exposure time for treatment of alfalfa seeds with levulinic acid plus sodium dodecyl sulfate (SDS) to inactivate Escherichia coli O157:H7 and Salmonella without adversely affecting seed germination. Alfalfa seeds inoculated with a five-strain mixture of E. coli 0157:H7 or Salmonella Typhimurium were dried in a laminar flow hood at 21 degrees C for up to 72 h. Inoculated alfalfa seeds dried for 4 h then treated for 5 min at 21 degrees C with 0.5% levulinic acid and 0.05% SOS reduced the population of E. coli 0157:H7 and Salmonella Typhimurium by 5.6 and 6.4 log CFU/g, respectively. On seeds dried for 72 h, treatment with 0.5% levulinic acid and 0.05% SDS for 20 min at 21 C reduced E. coli 0157:H7 and Salmonella Typhimurium populations by 4 log CFU/g. Germination rates of alfalfa seeds treated with 0.5% levulinic acid plus 0.05% SOS for up to I h at 21 degrees C were compared with a treatment of 20,000 ppm of calcium hypochlorite or tap water only. Treatment of alfalfa seeds with 0.5% levulinic acid plus 0.05% SDS for 5 min at 21 degrees C resulted in a >3.0-log inactivation of E. coli 0157:H7 and Salmonella.