On-Farm and Postharvest Processing Sources of Bacterial Contamination to Melon Rinds

Abstract

Multistate and international foodborne illness outbreaks, particularly involving cantaloupe and often involving rare Salmonella spp., have increased dramatically over the past 13 years. This study assessed the sources and extent of melon rind contamination in production fields and at processing and packing facilities. In the spring of 1999, cantaloupe (Cucumis melo L. [reticulatus group] cv. Cruiser) sampled from two sites in the Rio Grande River Valley showed that postharvest-processed melon rinds often had greater plate counts of bacterial contaminants than field-fresh melons. Cantaloupe in the field had 2.5 to 3.5 log CFU g−1 rind total coliforms by aerobic plate counts, whereas washed melons had 4.0 to 5.0 log CFU g−1. In the fall of 1999, coliforms on honeydew melons (C. melo [inodorous group] cv. Honey Brew) ranged from 2.6 to 3.7 log CFU g−1 after processing, and total and fecal coliforms and enterococci never fell below 2.5 log CFU g−1. A hydrocooler at another site contaminated cantaloupe rinds with up to 3.4 log CFU g−1 total and fecal enterococci; a secondary rinse with chlorinated water incompletely removed these bacteria. Sources of coliforms and enterococci were at high levels in melon production soils, especially in furrows that were flood irrigated, in standing water at one field, and in irrigation water at both sites. At one processing facility, wash water pumped from the Rio Grande River may not have been sufficiently disinfected prior to use. Because soil, irrigation water, and process water were potential sources of bacterial contamination, monitoring and management on-farm and at processing and packing facilities should focus on water quality as an important control point for growers and packers to reduce bacterial contamination on melon rinds.

Spatial and Temporal Factors Associated with an Increased Prevalence of Listeria monocytogenes in Spinach Fields in New York State

“…These findings are consistent with findings of previous studies (14,25,26,47,51,52) that identified irrigation water as a potential preharvest source of bacterial contamination of produce. Multiple studies have also reported significant associations between irrigation water and fresh produce contamination (12,13,19,20). The relationship between irrigation and L. monocytogenes isolation in this study may be explained by the fact that surface water is a known reservoir of foodborne pathogens in produce production environments (22,(52)(53)(54)(55)(56).…”

“…Although most listeriosis outbreaks associated with fresh produce are traced back to processing environments, the prevention of produce contamination in production environments is crucial. In fact, previous studies have shown that low-level sporadic contamination of produce in production environments can result in pathogen proliferation and widespread contamination throughout the supply chain (11)(12)(13). In order to minimize preharvest produce contamination, it is necessary to understand how different spatial (e.g., proximity to water and roads) and temporal (e.g., time since irrigation) factors affect the likelihood of a contamination event in production environments.…”

Scientific Opinion on the risk posed by pathogens in food of non-animal origin. Part 2 (Salmonellain melons)

“…The available literature, however, highlights contaminated irrigation water sources or insufficiently disinfected process water as the most probable sources for contamination during melon and watermelon production (Gagliardi et al, 2003;Castillo et al, 2004;McCallum et al, 2010). Amongst the Salmonella outbreaks associated with melon consumption, risk factors at pre-harvest were identified with contaminated soil, manure, irrigation water, water used in pesticide application and animals (rodents, birds, insects or reptiles) in the production area (Bowen et al, 2006).…”

“…There is more limited information on a restricted range of Salmonella serovars available for adherence to the surface of melon and watermelon types other than cantaloupe (Gagliardi et al, 2003;Parnell et al, 2005).…”

Influence of Vacuum Cooling on Escherichia coli O157:H7 Infiltration in Fresh Leafy Greens via a Multiphoton-Imaging Approach

“…This approach also mimics certain aspects of the cross-contamination process in which contaminated water may be sprayed on fresh produce during vacuum cooling. Sanitation of the processing water used during cooling and washing has been a subject of significant concern in the fresh produce-processing industry (19)(20)(21). In order to determine the average load sprayed onto the leaf disks, leaf disks with surface-inoculated E. coli O157:H7 GFPlux were prepared and vortexed in 5 ml of 1ϫ PBS buffer for 10 min immediately following inoculation.…”