Vol 120 (2007): Proceedings of the Florida State Horticultural Society
Handling & Processing

Microbiological evaluation of mechanically harvested citrus fruit

Renee Goodrich-Schneider
University of Florida
Published December 1, 2007
  • Citrus sinensis,
  • Salmonella,
  • Escherichia coli,
  • citrus processing


For Florida to effectively compete in the world citrus industry, significant reductions in harvesting costs will be necessary. Mechanical harvesting can be thought of a two-step process: removal of fruit from the tree, and retrieval of fruit from the ground and/or collection area. A citrus fruit pickup machine developed by OXBO International Corporation is being tested for performance and productivity. The machine is being evaluated for its picking up rate, efficiency, field capacity, and its efficiency for removing undesirable fruit and trash. The performance test is being conducted under different ranges of forward speed, orange variety, and grove conditions. This study evaluates the microbiological aspects of mechanically handled fruit with respect to fruit surface microflora. Three treatments were evaluated: hand-harvested fruit (control), mechanically harvested and dropped fruit picked up manually from the ground (MH/hand PU fruit), and mechanically harvested and dropped fruit picked up with the OXBO machine (MH/machine PU fruit). Microbial analysis included total plate count (TPC), acidophilic organisms, generic Escherichia coli (as an indicator of potential contamination), and Salmonella. Additionally, juice that was aseptically obtained from the three fruit samples was evaluated for microbiological quality. Finally, the approximate load of sand of the surface of the fruit was evaluated to determine potential impact on fruit handling equipment, which is known to be negatively impacted by the presence of abrasive foreign material such as sand. In general, within a particular harvest replicate, hand-harvested control fruit had similar microbial loads on the surface of the fruit as microbial loads on the MH/hand PU or MH/machine PU fruit. Escherichia coli and Salmonella were detected in three of the four replicates on fruit surface samples, but neither organism was obtained from any of the juice samples. There were substantial differences among the four replicate trials conducted in the 2006-07 season, which may have been due to a variety of factors, including differing grove care and floor conditions, weather, equipment sanitation, grove location, and tree/fruit treatments during production.