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.