P1-171 Efficacy and Stability of Disinfectant Solutions Applied to Papaya (Carica papaya) at Packing Facilities in Mexico

Monday, July 10, 2017
Exhibit Hall (Tampa Convention Center)
Jorge Adrián Muniz Flores , Universidad de Guadalajara , Guadalajara , Mexico
Jennifer A. Chase , University of California-Davis , Davis , CA
Edward R. Atwill , University of California-Davis , Davis , CA
Ma. Ofelia Rodríguez-García , Universidad de Guadalajara , Guadalajara , Mexico
Elisa Cabrera-Diaz , Universidad de Guadalajara , Guadalajara , Mexico
Introduction: Papaya exported from Mexico has been associated with Salmonella outbreaks and import alerts. Postharvest, papayas are immersed in subsequent tanks to wash and disinfect. The first tank (A) contains chlorine and a stabilizer and the second tank (B) contains peroxyacetic acid and thiabendazole. The efficacy of these solutions to control Salmonellahas not been evaluated. 

Purpose: To evaluate the efficacy and stability of disinfectant solutions used in papaya packing facilities in Mexico. 

Methods: Solutions were prepared according to industry standards and held at room temperature: solution-A contained 1.5ml/L of sodium hypochlorite (13% v/v) and 0.5ml/L of AquaRite stabilizer™; solution-B had 1.5ml/L of SaniDate5.0™ and 1.5g/L of Tecto60™. Free chlorine, ORP, temperature and pH were measured after 0, 2, 4 and 6h. At each time interval, 5ml of each solution were inoculated with a cocktail of six Salmonella serotypes including, Bredeney, Muenchen, C1, Oranienburg, Minnesota, and Typhimurium (6.3±0.2-log CFU/ml). After 30s, 5ml of double strength D/E neutralizing broth was added. Salmonella was enumerated on tryptic soy agar. Experiments were conducted in triplicate (n=72). Physicochemical parameters and Salmonellareductions were analyzed with ANOVA and LSD test (α=0.05).

Results: Solutions A and B had a mean ORP of 213±1.3 and 180±1.4mV, and pH of 3.3±0.3 and 3.8±0.2, respectively; these values were not significantly different (P>0.05) after 6h. Free chlorine concentration was 231±56mg/L with a slight reduction after 6h (P>0.05). Overall mean Salmonella reductions were 2.5±1.0 and 3.6±1.4 log CFU/ml in A and B, respectively; lower reductions were observed after 6h (P<0.05).

Significance: Under controlled conditions, the disinfectant solutions were stable after 6h, however, exhibited limited efficacy to reduce Salmonellaafter 30s of contact time. Additional field studies will evaluate the efficacy of disinfection solutions, to determine if an inhibitory effect occurs when soil or debris are introduced by harvested papaya.