Purpose: The purpose of this study was to evaluate the efficacy of chlorine, peroxyacetic acid (PAA), and chlorine dioxide (ClO2) to reduce Salmonella populations on the surface of mangoes during brush treatment.
Methods: Tommy Atkins mangoes were spot inoculated with 100 µl five-strain Salmonella (rifampicin-resistant) cocktail (eight log CFU/mango) onto the equator and dried for one hour. Not inoculated (negative control) or inoculated mangoes were washed with a laboratory-scale brush roller system with either ground water (control), or sanitizers (100 ppm free chlorine (pH=7), 80 ppm PAA, or 5 ppm ClO2) for 0, 5, 15, 30, and 60 s respectively (n=15). Dey/Engley buffer (100 ml) was added to whole mangoes in sterile bags to remove Salmonella from the surfaces using a rub-shake-rub method, then plated in duplicate onto selective and/or nonselective agar. Data were statistically analyzed by ANOVA and Tukey’s HSD test for effect of sanitizer and time.
Results: Chlorine, PAA, and ClO2 spray resulted in significantly higher (P<0.05) log CFU/mango reduction of Salmonella than water spray during brush roller treatment regardless of washing time. The highest log reduction with PAA treatment was at 60 s (5.07±1.05), compared with chlorine (4.43±0.91), ClO2 (3.81±0.29), and water treatment (3.27±0.50). In all cases, log reductions increased with longer treatment times. ClO2wash achieved at least 2.5 log reduction; chlorine and PAA wash achieved at least three-log and four-log reduction, respectively; while water wash alone achieved a 1.75-log reduction.
Significance: Addition of chlorine, PAA, or ClO2 to spray water used during brush treatment can lead to more effective food safety management, which will help to minimize contaminated mangoes entering the market.