Effectiveness of radiation processing in elimination of Salmonella typhimurium and Listeria monocytogenes from sprouts

The effectiveness of radiation treatment in eliminating Salmonella Typhimurium and Listeria monocytogenes on laboratory inoculated ready-to-eat sprouts was studied. Decimal reduction doses (D10-values) for Salmonella Typhimurium and L. monocytogenes in dry seeds of mung (green gram), matki (dew gram), chana (chick pea), and vatana (garden pea) ranged from 0.189 to 0.303 kGy and 0.294 to 0.344 kGy, respectively. In sprouts made from these seeds, the D10-values ranged from 0.192 to 0.208 kGy for Salmonella Typhimurium and from 0.526 to 0.588 kGy for L. monocytogenes. Radiation treatment with a 2-kGy dose resulted in complete elimination of 10(4) CFU/g of Salmonella Typhimurium and 10(3) CFU/g of L. monocytogenes from all the four varieties of sprouts. No recovery of Salmonella Typhimurium and L. monocytogenes was observed in the radiation treated samples stored at 4 and 8 degrees C up to 12 days. Radiation treatment with 1 kGy and 2 kGy resulted in a reduction of aerobic plate counts and coliform counts by 2 and 4 log CFU/g, respectively; the yeast and mold counts and staphylococci counts decreased by 1 and 2 log CFU/g, respectively. However, during postirradiation storage at 4 and 8 degrees C, aerobic plate counts, coliform counts, yeast and mold counts, and staphylococci counts remained constant throughout the incubation period. This study demonstrates that a 2-kGy dose of irradiation could be an effective method of processing to ensure microbial safety of sprouts.