An outbreak of Salmonella Adelaide infections is currently being investigated by the CDC, public health and regulatory officials, and the U.S. Food and Drug Administration. The outbreak has been attributed to pre-cut watermelon, honeydew melon, cantaloupe, and fruit medley products sold by Caito Foods, LLC. Sixty people from five states have been infected with the outbreak strain. Thirty-one have been hospitalized, and no deaths have been reported.
- Cantaloupes are a low-calorie source of vitamin A (β-Carotene), vitamin C, potassium, folic acid, iron, some dietary fiber, and calcium.
- The complex surface of cantaloupe makes it well suited for harboring pathogens.
- In recent years, cantaloupe has been the third most common produce item associated with foodborne illness outbreaks, with more than 30 outbreaks occurring from 1973 to 2012.
- Although Salmonella has been the cause of most of the outbreaks, Norovirus, Campylobacter, E. coli O157, Listeria, Shigella, and other pathogens have been associated with cantaloupe.
Cantaloupes (scientific name: Cucumis melo L. cantaloupe) are part of the Cucurbitaceae plant family, and are also known as the muskmelon (Cucumis melo). They are characterized by shallow ribs, finely netted rinds, and webbed surface—a network of fibrous and semi-porous tissue.
There are many cantaloupe varieties, and growers will select seed based on their region’s soil type and weather conditions.
Colorado farmers have been growing cantaloupes, and primarily the “netted gem” variation, for market since the Burpee company cultivar was introduced in the early 1880s. Although there are several dozen farms growing cantaloupes across the state of Colorado, most are grown in the Rocky Ford region in the southeastern portion of the state. Landowner, politician, and entrepreneur, George Washington Swink built the melon industry after he transformed the region by developing a canal-based irrigation system; he also introduced honeybees to the region and invented the cantaloupe crate.
Many consider Rocky Ford cantaloupes to be some of the best, they have fetched a premium price for more than a century. They are known for their quality and sweetness, which is the result of the seed used and the type of soil in the region—a sandy loam or clay-loam soil, as well as certain production practices used.
Colorado Cantaloupe Data
However, based on 2011 data, Colorado only ranks sixth among states in cantaloupe production—around 2% of total US cantaloupes. In most years, over 90% of cantaloupes were grown in California, Arizona, and Texas. Other important 2011 Colorado agricultural data are below.
- Acres planted: 2,200
- Dates planted: April 15 to May 15
- Acres harvested 2,100
- Total harvested: 39,900 pounds
- Dates Harvested: June 15 to October 15 (most by September 15)
- Typical growing period: 70-80 days
- Cash receipts in Colorado: 9,177,000
In the United States, in the period between 2000 and 2009, cantaloupes were the third most common produce item to cause foodborne illness, after leafy greens and tomatoes—although they were consumed in much lower quantities.
Although over half of all cantaloupe outbreaks have been due to Salmonella contamination, there have also been issues related to Norovirus, Campylobacter, E. coli O157, Listeria, Shigella, and other pathogens.
Although many cantaloupe outbreaks have been linked to imported fruit, the major, multistate listeriosis and salmonellosis outbreaks in 2011 and 2012 were associated with consumption of fresh cantaloupe from farms located in Colorado and Indiana, respectively.
Compared with other foodborne disease outbreaks, cantaloupe outbreaks have been more severe and widespread. Since 1985 there have been 1,520 illnesses, 297 hospitalizations, and 36 deaths (33 in the 2011 outbreak and 3 in the 2012 outbreak). The 2011 outbreak was the deadliest since 1924.
In February 2013 the director of the Center for Food Safety and Applied Nutrition at the FDA issued letters to members of the cantaloupe industry who grow, harvest, sort, pack, process, or ship cantaloupe, directing them to observe the existing best practices for food safety.
Soil & Planting
Cantaloupes are a warm-season annual plant that is sensitive to freezing temperatures at any growth stage. They grow best in sunny, hot weather, with minimal rain and low humidity, and they are typically planted in the spring after the soil temperature is above 65°F.
Sandy soils are used for the earliest plantings because they warm more rapidly in the spring, while loam and clay loam soils are preferred for main-season production due to greater water-holding capacity, which favors a prolonged harvest period.
Most cantaloupes are direct seeded, in a single seed line per bed. Seed is planted into pre-irrigated, moist soil under 3 to 6 inches of loose soil, and it is important that the soil is well drained to prevent root diseases.
Cantaloupes are often planted in raised beds, which helps irrigation water get to the roots while the surface remains dry. Also, a lightweight plastic film or mulch is often used to cover a seedbed. See plasticulture for details.
Cantaloupes produce both staminate and perfect flowers, the latter having both male and female parts and ultimately developing into the fruit.
Growing cantaloupes requires bee pollination; poor weather conditions (cold, rain, high wind, or prolonged cloud coverage) or use of pesticides that reduce bee activity may reduce yield.
If cantaloupes contact moist soil during the growing period, a “ground spot” may result. This is an area on the rind that is thin and poorly developed and appears as a cosmetic blemish. Presence of a ground spot increases the risk for mold and microorganism growth and accelerated decay and may be more susceptible to internalization by pathogens during post-harvest handling.
In some regions, growers will hand-turn melons to prevent development of a ground spot, increasing the potential for contamination (from human contact). However, ground spot formation can be prevented (without human contact with the melons) using other methods to keep cantaloupes off of the ground and dry, including proper planting-bed preparation and careful irrigation management.
Although it is not common practice, some growers may use animal manure and/or composts as soil amendments.
To qualify for organic certification, growers of organic cantaloupes must comply with requirements for composted and certified soil amendments.
Cantaloupes need plentiful water, and frequency of irrigation can vary from weekly to daily; there is considerable variation depending on weather, irrigation efficiency, leaching requirements, and need for pre-irrigation.
The water used during production and harvesting activities may come from a variety of sources, including municipal water, wastewater, ponds, rivers, lakes, wells, etc.).
Cantaloupe growers use a wide variety of irrigation methods to ensure soil is moist, especially prior to planting. One of the most popular and oldest methods is furrow irrigation, also known as surface or flood irrigation. Historically, most cantaloupe fields have been furrow irrigated. Many other growers have used sprinkler irrigation.
Another more “intensive” method, drip irrigation, has become increasingly popular for production of cantaloupe and other crops since the early 1990s. Most cantaloupes in Colorado are now grown using a combination of drip irrigation and plasticulture.
Preventing disease in cantaloupe plants
Certain cultivars can be susceptible to various fungi and viruses. Additionally, various weeds and insects may be problematic. To reduce risk of common disease problems, growers avoid planting cantaloupes immediately following other cucurbits or solanaceous crops (such as tomatoes, peppers, and eggplant) in the rotation for at least 3 years.
Some growers use pesticides and/or fungicide treated seed. Others may apply fungicide or whitewash foliar applications to prevent sunscald of ripening melons. Typically spray applications are terminated at least a week prior to harvest, except with certain approved materials to treat late-season leaf diseases.
Most Colorado growers are using varieties that are bred to be resistant to certain pests and have very little need for pesticides.
Harvesting, packing, and storage
Cantaloupes are harvested by hand, typically during what is known as the three-quarter- to full-slip stage, when melons are mature/ripe, with a more golden appearance, and the fruit is beginning to dehis (easily separate from the stem with a twist or pull) and sugar levels are highest. If pathogens are present during this time, they can become attached to the cantaloupe rind, particularly where the stem was removed (the stem scar).
Handling practices immediately following harvest differ by grower and farm location/region, and may impact food safety.
In some cases, cantaloupes are harvested, packed, and inspected in the field (placed directly into the final shipping unit or container), palletized, and then transported to a temperature controlled facility.
In other cases, they are harvested into field boxes, plastic bins, in trailers, or onto a conveyor belt machine, ultimately to be taken to shed packing-houses or other central packing facilities where they are packed in cartons or crates.
In the latter scenario, before the melons get packed and taken to cooling facilities, they are cleaned with brushes either while dry or after they are hydrocooled—through immersion in a dump tank or spraying with water (and in some cases disinfectant-treated water). Some producers may take other steps to remove soil or other contaminants from the surface of the melons to prevent mold development.
Cantaloupes are generally packed in 40 pound cartons and are typically stored at 36°F to 40°F prior to shipment.
For more information regarding the production and distribution of Cantaloupes please visit the Produce Point of Origin Database.
Unfortunately, physical characteristics of their rind and flesh make cantaloupes susceptible to pathogen contamination and growth, and cantaloupe consumption has been associated with many outbreaks in the last few decades—19 reported from 1973-2003 and 23 reported from 1985-2012.
As contamination can arise from soil, water, equipment, animals, or humans, and can occur at any phase of production (growth, harvesting, post harvest handling, packing, transportation, or distribution) it is important to understand the details of each. Also, production methods may vary considerably between growers or by region.
Consumer handling recommendations for safe handling of cantaloupe are to use soon after purchase and wash the outside rind thoroughly under clean running water, scrubbing with a clean vegetable brush to help remove soil or possible contamination before cutting. A clean knife and cutting board should be used and the knife should be rinsed after each cut. Cut melon should be stored at refrigerator temperatures and used within two to three days.
Worldwide, the United States is one of the largest consumers of melons. Americans eat an average of 27 pounds of melons per year, and 8.7 pounds of this is cantaloupe. Melon consumption has increased with the introduction of sweeter seedless and hybrid varieties. In the 2006-2007 Population Survey Atlas of Exposures, 31.6% of the survey cohort reported eating cantaloupe within the past 7 days.
More information on how to keep cantaloupe stored properly please visit FoodKeeper App.
Cantaloupes are a low-calorie (27 calories per 1/2 cup serving), nutrient dense fruit. They are a rich source of vitamin A (β-Carotene), vitamin C, potassium, folic acid, and the micronutrients copper, iron, and zinc. Cantaloupe is naturally low in sodium and contains some dietary fiber and calcium.
Externally Reviewed by: Mike Bartolo, PhD Affiliation: CSU Department of Horticulture and Landscape Architecture, Vegetable Crop Senior Research Scientist and Extension Specialist Reviewed on: 3 November 2015