assessment OF SaNIDaTe 5.0

Transcription

1 22 Meadow Street East Hartford, CT (toll-free) fax: PRINCIPAL INVESTIGATOR(S): Alejandro Tomas Callejas, Gabriela Lopez-Velasco, Trevor Suslow, University of California Davis, CA CROP: ORGANISM: Cantaloupe (Cucumis melo) Listeria innocua assessment OF SaNIDaTe 5.0 and other chemical sanitizers against Listeria innocua on cantaloupes, 2012 The most recent outbreak of foodborne illness from consumption of Listeria infected cantaloupes has been a great concern for the melon industry and also for the consumers. Investigations into such incidents have highlighted the risk of not using an antimicrobial in the wash water used for cleaning the melons before packing. The causal organism in Listeria outbreaks is more commonly associated with Listeria monocytogenes, a gram positive facultative anaerobic bacterium known to cause Listeriosis in humans. The netted skin on produce like cantaloupe can provide a safe harbor for such microbes and present an obvious challenge in terms of effective sanitation of the fruit surface. Over the last few years, researchers have been evaluating various treatment methods that could effectively combat this pathogen before it gets into the food system. This study is part of such research efforts by University of California-Davis (UCD) on foodborne pathogens in melons and other produce. materials AnD methods: Study was conducted in Spring of 2012 at Louis K. Laboratory, Department of Plant Sciences, UCD. Cantaloupes used for testing were obtained from General Produce Company, Sacramento, CA. The test organism was Listeria innocua (ATCC-33090), an avirulent/non-pathogenic strain with phenotypic similarities to the pathogenic strain Listeria monocytogenes. Inoculation procedure involved spot inoculation at two different sites on each cantaloupe using 2 inoculum levels (Log 5 and Log 7). Treatments tested in the trial are presented in Tabel 1. The BioSecurity Company 1

2 Table 1. Treatments evaluated in the Study Treatment Manufacturer Dose (mg/l) a Contact Time Control No washing 0 Water 0 2 minutes Unknown 50 2 minutes SaniDate 5.0 BioSafe Systems 85 b 2 minutes PRO-SAN LC Microcide Inc minutes a Dose represents active ingredient in the chemical sanitizer b Active ingredient in SaniDate 5.0 is represented as Peracetic Acid Washing unit included a plastic container containing 5 liters of disinfectant solution and 6 inoculated melons per treatment. Disinfectant solutions were prepared immediately before processing. Experiments were performed at room temperature. After treatments, cantaloupes were stored at 5 C after processing for up to 13 days. Recovery and detection was carried out after processing (Day 0) and 7 and 13 days after post-washing. Recovery and detection include melon peel (2 3 cm. diameter) homogenized by hand in khpo4 + Tween 20. Selected colonies and enrichments were confirmed by spot plating onto Oxford + high rif plates. Results: Inoculum Level Log 5: The initial inoculum level is 1.75 x 105 cells per fruit. The final concentration after drying is 3.53 log CFU per fruit. Initial log reduction on Day 0 was 1.18 log for SaniDate 5.0 treatment (Table 2; Fig. 1). After 13 days at 5 C, Listeria was below limit of detection for SaniDate 5.0 and sodium hypochlorite treatments. Percent positives for Listeria after enrichment was 0% with SaniDate 5.0 and 50% with sodium hypochlorite. Inoculum Level Log 7: The initial inoculum level is 1.75 x 107 cells per fruit. The final concentration after drying is 5.67 log CFU per fruit. Initial log reduction on Day 0 was 3.42 log for SaniDate 5.0 treatment (Table 2; Fig. 2). 2 The BioSecurity Company

3 Table 2. Efficacy of different chemical sanitizers on population of Listeria innocua at two different inoculum levels Log 5 Day 0 Day 7 Day 13 Log CFU/Fruit SD a Log CFU/Fruit SD a Log CFU/Fruit SD a Control Water SaniDate PRO SAN LC Log 7 Day 0 Day 7 Day 13 Log CFU/Fruit SD a Log CFU/Fruit SD a Log CFU/fruit SD a Control Water SaniDate PRO-SAN LC a SD Standard Deviation The BioSecurity Company 3

4 Figure 1. Efficacy of Different Chemical Sanitizers on Listeria Innocua at Inoculum Level-Log Log CFU/Fruit Untreated Control Water Only SaniDate 5.0 Pro-San LC Day Day Day The BioSecurity Company

5 Figure 2. Efficacy of Different Chemical Sanitizers on Listeria Innocua at Inoculum Level-Log Log CFU/Fruit Untreated Control Water Only SaniDate 5.0 Pro-San LC Day Day Day The BioSecurity Company 5

6 Conclusions: Results from this study show that SaniDate 5.0 at 85 PPM Peracetic Acid (PAA) and other chemical treatments on an average across 13 day storage period provided significant log reduction of inoculated Listeria innocua when applied as a wash with a 2 minute contact time. Even though some variations in log reductions were observed based on the initial inoculum level and evaluation periods, SaniDate 5.0 in general has shown a greater effect in reducing the L. innocua population compared to other chemical sanitizers tested in this study. Additional lab and on-site trials need to be conducted with this product to further evaluate and prove its potential for use in commercial melon wash applications. Note: The content and conclusions in this report are based on the data from research by UCD. For any additional information on the study, please contact BioSafe Systems at info@biosafesystems.com (toll-free) Fax: The BioSecurity Company