Cucumber Food Safety FAQs and Resources

Cucumbers are one of the most popular and important commodities in the U.S. with approximately 2.8 billion pounds being available for consumption every year. Nevertheless, most of the cucumber availability is from foreign origin. In 2023, the U.S. produced approximately 337 million pounds and imported 2.54 billion pounds (89 percent of the cucumbers consumed in the United States). Figure 1 shows the trends in availability by origin; imports have increased, and domestic production has decreased (ERS data).

In the U.S., cucumbers are mostly produced in Michigan (37 percent), Florida (23 percent), North Carolina (11 percent), Georgia (10 percent), and California (8 percent), (USDA Vegetables 2022 Summary). The U.S. production of cucumbers is seasonal with most production happening in the summer, during the winter, autumn and spring months. Fresh cucumbers are mostly imported (USDA ERS). Origin of imported cucumbers include Mexico (62 percent), Canada (36 percent), the Dominican Republic (1.17 percent), and Honduras (0.77 percent) (BACI data for 2021).

What pathogens are commonly associated with cucumbers?

Cucumbers have been linked to several foodborne illness outbreaks, primarily caused by Salmonella. In 2016, the FDA reported a Salmonella incidence of 1.8 percent positivity in nearly 1,600 cucumber samples, where those contaminated were 39.3 percent produced in the U.S., and 60.7 percent imported. Nevertheless, contamination with other pathogens may occur during irrigation, improperly treated soil amendments and animal intrusion (Colorado State University). Below are several notable multistate foodborne illness outbreaks attributed to cucumbers.

November 2024 Outbreak: 68 individuals across 19 states have reported infections from Salmonella Typhimurium linked to cucumbers grown in Mexico.

June 2024 Outbreak: In June 2024, the FDA and CDC investigated a multistate outbreak of Salmonella Africana infections potentially linked to cucumbers. Cucumbers grown in Florida distributed to several states were later recalled after a sample tested positive for Salmonella.

2015 Outbreak: In 2015, a significant Salmonella Poona outbreak in the U.S. was traced to cucumbers imported from Baja California, Mexico. The outbreak resulted in 907 reported illnesses across 40 states, including 204 hospitalizations and six deaths.

2013 outbreak: The Salmonella Saintpaul outbreak was traced to cucumbers imported from Mexico, resulting in 84 illnesses and 17 hospitalizations. On April 24, 2013, the FDA halted cucumber imports and issued an import alert for two trading companies involved in the distribution.

How are cucumbers grown and harvested?

Planting: Cucumbers are typically grown in fields or greenhouses with careful attention to soil quality, water management and hygiene to ensure both optimal production and food safety. The process begins with preparing soil that is well-drained and adequate for plant growth. They are planted when soil temperatures exceed 60°F and air temperatures do not fall below 50°F at night. Seeds are planted in adequately spaced rows. (Penn State, UC Davis)

Irrigation: Irrigation plays a critical role in cucumber growth and food safety, with methods like drip or furrow irrigation commonly used to deliver water directly to the plant roots while minimizing contact with the fruit. Cucumbers need frequent irrigation during the growing period. (UC Davis)

Irrigation water can be a source of contamination and could carry microorganisms of public health concern, including Salmonella, pathogenic E. coli and human viruses like hepatitis. A. The following aspects need to be considered when managing your irrigation water:

Source of water (Surface, Ground, Municipal)

Timing for irrigation (extended time before harvest allows time for pathogen die-off)

Application (overhead (riskier), flood, and furrow, or sub-surface (less risky))

Timing: Cucumbers are generally harvested 30-46 days from planting. This is widely dependent on the variety and weather conditions. (OSU, UC Davis)

Harvest: Cucumbers are typically picked by hand or machine once they reach the desired size and maturity. Workers handling the harvest are trained in proper hygiene practices (washing hands and cleaning and sanitizing knives/pruners if used)_ to reduce the risk of cross-contamination. (WKU) Harvesting equipment and containers are also cleaned and sanitized regularly to maintain food safety.

Greenhouse cucumbers: Cucumbers grown in greenhouses differ in some areas from those in the field. Generally greenhouse cucumbers are of the English verities (covered in plastic). Greenhouse cucumbers are often grown vertically using trellises in high tunnels to increase density. These are generally growing in substrate-based systems. The commonly used substrates are perlite, pine bark, and rock wool. Perlite, a heat-expanded volcanic rock, is lightweight and porous but does not hold nutrients. Pine bark, an organic material milled to about 1/2 inch and aged before use, can retain some nutrients. Rockwool, often used in high-wire systems, comes in cubes or slabs placed on plastic troughs for nutrient drainage. It is also used in seedling blocks for transplant production. Irrigation systems often use drip systems to deliver precise water and nutrients directly to the plant roots. Most cucumbers produced in Canada are grown in Greenhouses, while those grown in Mexico can be both field cucumbers (39%) or greenhouse cucumbers (61%) (Rural Migration).

What are post-harvest practices for cucumbers?

Storage and Holding: Post-harvest, cucumbers are cooled quickly to remove field heat. Methods for cooling harvested cucumbers include hydrocooling with chilled water and forced-air cooling. Cucumbers are held in chill rooms at approximately 50°F. (UC Davis)

Washing: Cucumbers are washed, sorted and graded in a packing house after being harvested and transported from the field. The wash system scrubs the cucumbers to remove adhering dirt and residues. To control microbial contamination, the wash water is often treated with sanitizing agents such as chlorine, typically at concentrations between 100 to 150 ppm. Maintaining appropriate water temperature and pH levels is crucial to enhance the efficacy of (FAO)

What are food safety implications of the waxing process?

Fresh cucumbers are generally waxed to enhance visual appeal and reduce moisture loss. Cucumbers are waxed with food-grade waxes that are edible and approved by the FDA. These waxes are typically made from plant-based materials or petroleum-based waxes. Waxes are applied by using mechanical brushes. Most cucumbers in the fresh market are waxed except for English cucumbers, which are generally wrapped in plastic.

The cucumber waxing process has several food safety implications, primarily concerning bacterial survival and the potential for cross-contamination.

A study conducted in 2021 shows that Salmonella can survive better on waxed cucumbers than unwaxed ones in the short term, although unwaxed cucumbers may retain higher bacterial concentrations by the end of storage. The type of wax applied also influences Salmonella survival, with vegetable-based wax showing a significant decline in bacterial populations, whereas mineral oil and petroleum-based waxes allowed for Salmonella persistence over seven days at various temperatures. The study also highlighted cross-contamination is another critical concern. During the waxing process, Salmonella can transfer from contaminated cucumbers to brushes used for waxing and subsequently to uninoculated cucumbers.

These findings highlight the need for strict hygiene and sanitation practices during the waxing process to mitigate the risk of Salmonella contamination and ensure food safety in post-harvest handling.

What are some best practices and food safety considerations for cucumbers?

Pre-harvest practices:

Assess the water for irrigation to prevent contamination with pathogens like Salmonella and E. coli.

Avoid using untreated or poorly treated manure as a soil amendment.

Prevent animals from accessing growing fields to reduce the risk of fecal contamination. Evaluate for evidence of animal intrusion when harvesting and take corrective measures.

Worker Hygiene: