Purpose: The main objective of this study conducted during the 2013 and 2014 harvesting seasons at five growing regions in Florida was to evaluate the efficiency of post-harvest processing of tomatoes in commercial packinghouses.
Methods: Determination of total aerobic plate count (APC), total coliforms (TC) and generic E. coli (EC) on 720 composite samples (five tomatoes per sample) both before and after processing were carried out to accomplish this objective. APC was determined using standard plate count agar (Thermo Fisher Scientific, Waltham, MA) and TC and EC were determined using ECC CHROMagar (DRG International, Inc., Mountainside, NJ). One hundred ml of 0.1% (w/v) sterile peptone water (PW) (Thermo Fisher Scientific, Waltham, MA) was added to the sterile sample bags with tomatoes and rubbed for 60 s. One hundred µl of each dilution was spread plated onto appropriate agar plates.
Results: The least square mean (LSM) value of APC for pre-processed samples was 6.6 log CFU/tomato, which was significantly lower (P<0.0001) in post-processed tomatoes to 5.8 log CFU/tomato. Similarly, the LSM for TC counts was 4.4 log CFU/tomato in pre-processed samples, whereas it reduced to in 4.1 log CFU/tomato in post-processed samples. Eighty-six out of 720 (11.9%) and 701 out of 720 (97.3%) samples had TC and EC counts below the detection limit of 1.3 log CFU/tomato. There was no significant difference in the occurrence of generic E. coli in pre- and post-processed samples. The APC and TC counts showed significant (P<0.0001) seasonal variation.
Significance: Information from this study is suitable for determining areas in which improvements may be made to optimize standard post-harvest operational procedures to ensure food safety and subsequently control disease outbreaks.