T7-01 Cantaloupe Fruit Microbiome:  Responses to Field Location, Cover Crop, and Cold Storage

Tuesday, July 11, 2017: 1:30 PM
Room 15 (Tampa Convention Center)
Maria Albarracin , North Carolina State University , Raleigh , NC
Christopher Gunter , North Carolina State University , Raleigh , NC
Penelope Perkins-Veazie , North Carolina State University , Kannapolis , NC
Benjamin Chapman , North Carolina State University , Raleigh , NC
Jonathan Baros , North Carolina State University , Kannapolis , NC
Sophia Kathariou , North Carolina State University , Raleigh , NC
Eduardo Gutierrez-Rodriguez , North Carolina State University , Raleigh , NC
Introduction:  Seasonal rain events during fruit formation and close to harvest are common during East Coast cantaloupe production and can result in soil/debris coming into contact with the fruit surface. Utilization of row cover crops, as physical barriers between soil and fruit, could be an alternative practice to prevent fruit contamination.

Purpose:  This study was a determination of the effect of cover crops during cantaloupe cultivation in reducing soil/plant residues and pathogen contamination during the growing season.

Methods: Cantaloupe was grown at three different locations following commercial practices. At each location, three different row cover crops (Buckwheat (Fagopyrum esculentum), sunhemp (Crotolaria juncea), and mustard (Brassica sp.)) were grown between rows forming a physical barrier between soil and fruit. Cantaloupe was hand harvested, kept in individual bags according to field location and cover crop practice and stored for 24 to 36 h at 15°C before processing. Aerobic plate counts (APC) and presence of generic Escherichia coli, coliforms, Enterococci spp., Salmonella spp., Shiga toxin-producing Escherichia coli (STEC), and Listeria monocytogenes were determined from fruit surfaces after harvest and storage at 4°C (two weeks).

Results: Soil and cantaloupe microbial communities varied only by location. Salmonella spp. was present at 7, 60, and 0% in soil collected from locations 1, 2 and 3, respectively. Listeria monocytogenes was not detected; neither on soil nor fruit samples. STEC was present in soil from all locations at 60, 13, and 10%, respectively. Cantaloupe APC, Enterococci spp., coliforms, and generic E. coli populations were significantly higher (P<0.05) in location 1 than 2 or 3. Irrespective of location and cover crop, cantaloupe APC, Enteroccocci spp., coliforms, Salmonella spp., and STEC significantly decreased during cold storage (4°C). Salmonella spp. and STEC persisted for up to two weeks during cold storage on fruit harvested from locations 1 and 2 (18 and 12%, respectively).

Significance: Preharvest pathogen cross-contamination of cantaloupe were mainly impacted by agronomic practices within each location, irrespective of mitigation practice.