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P3-111 Efficacy of Chlorine and Peroxyacetic Acid on Reduction of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., and Natural Microflora on Mung Bean Sprouts

Wednesday, July 31, 2013
Exhibit Hall (Charlotte Convention Center)
Shan Yu Neo, Agri-Food & Veterinary Authority of Singapore, Singapore, Singapore
Gek Hoon Khoo, Agri-Food & Veterinary Authority of Singapore, Singapore, Singapore
Pei Yan Lim, National University of Singapore, Singapore, Singapore
Li Kai Phua, National University of Singapore, Singapore, Singapore
Su-Jung Kim, Kyungnam University, Changwon, South Korea
Seung-Cheol Lee, Kyungnam University, Changwon, South Korea
Hyun-Gyun Yuk, National University of Singapore, Singapore, Singapore
Introduction: Sprouts-related outbreaks have risen due to increased raw sprouts consumption. To minimize such cases, chemical sanitations are applied. While chlorine (Cl) is commonly used, concerns with its effectiveness and health implications have prompted researchers to seek alternatives. Peroxyacetic acid (PAA) has been shown its efficacy in inactivating foodborne pathogens on fresh vegetables, thus it would be considered an alternative.

Purpose: The objective of this study was to compare the efficacy of Cl and PAA in inactivating Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., and natural microflora on mung bean sprouts. Resistance of non- and acid-adapted pathogens to sanitizers was also evaluated.

Methods: All pathogens were adapted to 100 ppm nalidixic acid and the acid-adapted cells were prepared by culturing in trypticase soy broth containing 1% glucose. Uninoculated or inoculated sprouts were treated with Cl at 106, 130 and 170 ppm and PAA at 25, 51 and 70 ppm for 90 and 180 s at room temperature. Mean values of bacterial counts were compared using ANOVA.

Results: Overall, the greater log reductions were obtained with the increase in the treatment time and the sanitizer concentration. For 180 s, Cl treatment at 170 ppm reduced 2.0, 1.3, 1.5, 0.9-logs and PAA treatment at 70 ppm resulted in 2.3, 1.8, 2.1, 1.1-log reductions for non-adapted E. coli O157:H7, L. monocytogenes, Salmonella spp., and natural microflora, respectively. These results revealed that the efficacy of PAA was significantly (P < 0.05) better or similar to that of Cl. These sanitizer treatments on acid-adapted cells were less effective with 1.0 – 1.2-log reductions for Cl and 1.1 – 1.6-log reductions for PAA compared to non-adapted cells.

Significance: These data suggest that PAA may replace chlorine in the disinfection of mung bean sprouts and the acid-adapted pathogens should be used to design an effective sanitizing strategy.

Back to: Poster Session 3 - Applied Laboratory Methods, Novel Laboratory Methods, Produce, Risk Assessment
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