Ultraviolet-C irradiation for reducing Escherichia coli and Salmonella sp. on asparagus spears

This research was to study on the decontamination of two foodborne pathogenic bacteria (Escherichia coli and Salmonella sp.) on asparagus spears using ultraviolet-C (UV-C) irradiation. Fresh asparagus spears were inoculated with each suspension of Escherichia con or Salmonella sp. (105 CFU mL(-1)). The sample was compared with the effect of UV-C irradiation for 1 min after inoculated each bacterial species, which was compared to fresh asparagus spears (control). Asparagus spears were packed in foam trays, wrapped with PVC films (14 mu m thickness). The packages were stored at 10 degrees C (85% RH) for 9 days. Escherichia coli, Salmonella sp., total microbial, yeast and molds counts on asparagus spears were enumerated during storage. Fresh asparagus spears had an initial Escherichia coli count of 2.4 log CFU g(-1), whereas Salmonella sp. count was about 1.8 log CFU g(-1). UV-C irradiation did not reduce both of Escherichia coli and Salmonella sp. count of asparagus spears inoculated with Escherichia coli or Salmonella sp. compared to un-irradiated inoculated sample. After storage at 10 degrees C, UV-C irradiation reduced Escherichia coli count to about 0.1 log CFU g(-1) on day 6, whereas it reduced Salmonella sp. counts of asparagus spears inoculated with Salmonella sp. about 1.0 log CFU g(-1). Total microbial and fungi counts of all asparagus spears were increased during storage. UV-C irradiation delayed microbial and fungi count compared to un-irradiated sample.