Purpose: The objective was to quantify microbial indicators on tomatoes sampled along the supply chain, in order to observe the magnitude of population changes due to ambient conditions.
Methods: Roma tomatoes (n=475) were taken from the same lots (n=28) at four locations of the postharvest supply chain over five months: at arrival to and departure from the packinghouse, at the distribution center and at supermarkets. Samples were analyzed individually for four microbial populations: aerobic mesophiles, total coliforms, generic Escherichia coli, and yeasts/molds. Statistical analyses of log CFU/tomato surface were made using generalized linear models (PROC GLM, SAS 9.3) with Tukey-adjusted P-values.
Results: Population means and standard deviations for aerobic mesophiles were 2.3±1.1, 1.91±1.1, 2.6±1.1 and 3.8±1.4 log CFU/tomato at postharvest, packing, distribution center and supermarket, respectively. Total coliform populations were below the detection limit at postharvest, but were detectable at packing, distribution and supermarkets at means of 0.86±1.1*, 0.48±0.9*, and 1.6±1.6 log CFU/tomato, respectively. Generic E. coli was not detected in this supply chain. Yeast/mold populations remained <1 log CFU/tomato, with the exception of 1.4±1.3 log CFU/tomato at supermarkets, indicative of minimal product spoilage. *Actual minimum is zero.
Significance: The means reported demonstrate the dynamics within populations as influenced by supply chain logistics and conditions, while the large deviation in some locations indicates opportunities for improvement. Overall, packinghouse and supermarket locations were identified as crucial points to control microbial safety risks.