Purpose: The goal of this work was to quantify the effectiveness of sanitary treatments on indicator organisms, on tomatoes, in New Jersey packinghouses. Factors that influenced treatment efficacy were also examined.
Methods: Twenty samples of 5 tomatoes each were collected before and after sanitary treatment from 5 NJ packinghouses at 5 different times over a 3-year period (1,000 samples, 5,000 total tomatoes). Chlorine or peroxyacetic acid was applied to the tomatoes via a dump tank or spray bars. Treatment concentration varied between packinghouses and over the course of the study. Samples were plated on plate count agar and CHROMagar ECC to determine total plate, coliform, and presumptive E. coli counts. Colonies were enumerated and bacterial populations were expressed in log CFU/tomato.
Results: Packinghouse A had a higher percentage of E. coli positive samples (5-85%) after the sanitary treatment vs. before (0-20%). Packinghouse B exhibited the highest consistent mean reductions per trial for total plate count (0.35±1.00 to 1.67±0.91 log CFU/tomato) and coliform count (0.59±1.49 to 1.56±1.24 log CFU/tomato). Packinghouses C and E had consistently minimal total plate count reductions (0.45±0.73 to 0.74±0.89 log CFU/tomato and -0.1±0.50 to 0.75±0.64 log CFU/tomato, respectively). Packinghouse C had the least reductions in coliform count (-0.14±0.83 to 0.56±0.92 log CFU/tomato). Packinghouse D results were inconsistent with total plate count reductions ranging from 0.09±0.66 and 1.15±0.86 log CFU/tomato. Overall, statistically significant reductions occurred in only 2 or 3 out of 5 sampling times at each packinghouse.
Significance: Each of the 5 packinghouses used different sanitary procedures that resulted in a wide range of bacterial reductions. Our research suggests that sharing and standardization on a common set of best sanitary procedures may aid NJ packinghouses in achieving more consistent bacterial reductions.