P3-115 Inactivation of Salmonella on Cantaloupes and Green Onions Using Pulsed Light (PL) and PL-Surfactant or Sanitizer Combination

Wednesday, July 31, 2013
Exhibit Hall (Charlotte Convention Center)
Wenqing Xu, University of Delaware, Newark, DE
Changqing Wu, University of Delaware, Newark, DE
Introduction: Cantaloupes have been associated with several multi-state outbreaks of foodborne salmonellosis across the U.S. and Canada since 1990. In 2012, the salmonellosis outbreak related with cantaloupes has infected 261 people in 24 states and caused 3 deaths. Imported green onions have been associated with three large outbreaks in the USA. Salmonella contamination has been found on both domestic and imported green onions.

Purpose: The objective of our study was to investigate Salmonella inactivation efficacy of pulsed light (PL) as well as its combination with surfactant or sanitizers on cantaloupes and green onions.

Methods: Cantaloupe rind was separated from the flesh and cut into 5 × 5 cm2 square to focus on the outer surface contamination. Green onions were cut into two segments, stems and leaves, to represent two different matrixes. Salmonella St. Paul (cantaloupe outbreak strain) was used for cantaloupe inoculation, while Salmonella Newport H1275 (sprout outbreak strain) was used for green onion inoculation. Dip inoculation method was applied by dipping fresh produce into 107 CFU/ml inoculum.

Results:  Results showed that 60 s PL treatment (1.37 log CFU/g) was significantly more effective than 200 ppm chlorine washing (0.65 log CFU/g) on cantaloupes. And PL treatment (0.97 and 1.45 log CFU/g ) was comparable with 200 ppm chlorine washing on both green onion stems and leaves (1.17 and 1.55 log CFU/g). PL combined with surfactant sodium dodecyl sulfate (SDS) was found to be more effective than single treatments of PL and SDS on green onions but not on cantaloupes. The combination of PL and 1000 ppm of SDS reduced the Salmonella populations dipped inoculated on the stems and leaves of green onions by 1.44 and 2.99 log CFU/g, respectively.

Significance: Novel technique PL could be used as an alternative to chlorine washing for cantaloupes and green onions. And PL-SDS combination provided higher log reduction than single treatments on green onions.