Posts Tagged ‘produce food safety’

UMD Researchers Seek Tomato and Leafy Greens Farm Participants

Friday, June 22nd, 2012

Sasha Marine, UMD Postdoctoral Research Associate;

In recent years, outbreaks of Salmonella, Listeria and E. coli in fresh vegetables and the resulting public concern over food safety has prompted regulators to re-evaluate production and post-harvest practices. Research has demonstrated the importance of Good Agricultural Practices (GAPs) and Good Hygienic Practices (GHPs) for preventing contamination and the subsequent growth of pathogenic microorganisms. As a result, protocols (referred to as “metrics” by the food industry) have been established by specific commodity groups and retailers, as well as by state and federal organizations. However, knowledge gaps remain as to the risk factors and adaptability of these protocols to different climates, regions and types of farming operations. It is important that any protocols be suited to implementation on small- and medium-sized farms, which are typical to Maryland and Delaware.

Thanks to a multi-state grant from the USDA National Institute of Food and Agriculture, University of Maryland researchers Kathryne Everts and Christopher Walsh will be collecting data from several small- and medium-sized farms in Maryland and Delaware to examine the influence of water sources and environmental parameters on the microflora on tomatoes and leafy greens. The scientific and technological knowledge gained from the 3-year project will be used to develop, refine and defend national food safety protocols for domestic and imported produce. Data generated from this project will also be incorporated into an upper-division undergraduate course being developed by Walsh and faculty at the University of Delaware and the University of Florida.

Farmers wishing to participate in this project may contact Sasha Marine (

Third Party GAP/GHP Audits and Produce Food Safety Plans

Thursday, April 26th, 2012

Gordon Johnson, Extension Vegetable & Fruit Specialist;

Produce growers in Delaware selling directly to supermarkets, food service companies, and some wholesale distributors are being required to have a third party Good Agricultural Practices and Good Handling Practices (GAP/GHP) audit by these buyers. This is to insure that good food safety practices are being used in growing, harvesting, packing, and shipping produce.

Most of these buyers are accepting the Harmonized GAP/GHP standards that the industry and the USDA have worked on together to standardize the audit process (a few buyers have other requirements).

Harmonized GAP and GHP standards can be found at:

The audit process requires that a farm create a food safety plan and then implement that plan on the farm. The grower will then choose a private food safety auditing company, the USDA, or the state department of agriculture to perform the audit during the harvesting season. They will review the records documenting that the food safety plan is being carried out and then will inspect the growing areas and packing facilities. If the farm passes the audit, this will then satisfy the buyer’s requirements.

In Delaware, the Delaware Department of Agriculture can conduct a USDA audit using the harmonized standards.

For assistance with developing a produce food safety plan for your farm, contact Gordon Johnson, Extension Fruit and Vegetable Specialist with the University of Delaware

Food Safety and Flooded Vegetable Fields

Friday, August 26th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist;

In produce fields that are flooded, another consideration for growers is food safety. The following is a good article on the subject from Steve Reiners at Cornell University.

There are two types of flooding. The first is more typical and occurs after a heavy downpour when fields become saturated and water pools on the soil surface. This type of flooding can reduce yields and even kill plants but usually will not result in contamination of produce with human pathogens.

The second type of flooding is more severe and seen less often. Standing water in fields that is runoff from stream/river overflows will more likely be contaminated with human pathogens. Unless flooding was light and there is no danger of bacterial contamination from floodwater, do not use fruits and vegetables that were ready for harvest at the time of flooding. Some fruits and vegetables are more susceptible than others to bacterial contamination.

Leafy vegetables (such as lettuce, cabbage, mustard, kale, collards, spinach, and Swiss chard) along with strawberries are more likely to be contaminated. Silt and other contaminants may be imbedded in the leaves, petioles, stems, or other natural openings of fleshy structures and can be difficult to remove. Do not use if mature when flooded.

Root, bulb, and tuber crops such as beets, carrots, radishes, turnips, onions, and potatoes are less susceptible to bacterial contamination. Produce with a protected fruit or impervious outer skin such as peas, melons, eggplant, sweet corn, or winter squash may be contaminated on the surface.

It is extremely important that produce be properly washed to reduce contamination.

To control postharvest losses, it is recommended that produce be washed in chlorinated water before storage or shipping (see table below). The wash temperature should be about 10°F warmer than the produce temperature to ensure that decay organisms are not sucked into the tissue. Since chlorine is most effective at a slightly acidic pH, it is important that wash water is buffered to adjust the pH to between 6 and 7.

Chlorine in the wash water is often inactivated when the wash water becomes dirty. Use filtering devices to remove soil and organic material, and check the chlorine concentration often. Produce should be subjected to the chlorinated wash from one to ten minutes. After it is removed, allow it to drain for several minutes before packing. NOTE: Leafy vegetables at or near harvest that were flooded with stream/river overflows should not be harvested or consumed. Chlorinated wash water will not eliminate likely human pathogens on their surface.

Amount of sodium hypochlorite to add to wash water for 50-150 PPM dilution.

Target ppm


tsp/5 gal

cup/50 gal

Sodium Hypochlorite, 5.25%





















Sodium Hypochlorite, 12.75%






















E. coli O104:H4 Outbreak in Germany

Friday, June 3rd, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist;

The produce industry in Europe has been affected by an outbreak of food-borne illness from a new strain of E. coli (O104:H4) which has sickened over 400 adults and killed 19. Recommendations have been for German consumers to stop eating produce or to cook produce. Particularly hard hit are growers of produce consumed fresh. Produce sales have been so hard hit in countries such as Spain that the EU is considering an aid program to compensate farmers for losses.

Originally, German officials blamed cucumbers from Spain because they found toxic E. coli on cucumbers imported from that country. However, the strain found in those who were sickened did not match the strain found on Spanish cucumbers. Currently, no other potential source has been identified, but salad items are suspected.

New toxic strains of E. coli have been emerging throughout the world. Bacteria are well adapted to exchange genetic material and a previously non-toxic organism can become toxic by picking up genes for toxin production from another bacteria. Some of these toxic strains are particularly dangerous because they can shut down the kidneys of persons infected.

Produce growers in the US and locally, especially direct marketers, may be asked by customers about this outbreak and the potential for it being found in US grown produce. This new strain in Europe has not been found in the US food supply and consumers should not be concerned.

However, growers should be aware that toxic strains of E. coli (O157:H7) do exist in this region. The major source is fecal matter from animals (domestic and wild such as cattle and deer) and irrigation water contaminated with fecal matter. Growers should take all precautions to avoid or eliminate contamination of produce from these sources.


Fruit and Vegetable Growers Association of Delaware Hires a Special Programs and Outreach Coordinator

Friday, April 8th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist;

The Fruit and Vegetable Growers Association of Delaware has just hired Sara Busker as their Special Programs and Outreach Coordinator. Sara is a University of Delaware graduate and grew up on a dairy farm near Harrington, Delaware. She was very active in 4-H and FFA and has extensive leadership and public presentation experience in those youth organizations. She was a former Delaware Dairy Princess and in that role gain experience planning activities that promoted DE products to farm audiences, consumer groups, and school groups. She also served for 2 years as the Kent County 4-H Summer Day Camp Director working with children ages 5-12 and is currently also a site coordinator for a 4-H After-School program in Dover with an everyday focus on teaching children to eat well. In addition, Sara works part-time for the Delaware Department of Agriculture and is currently working on updating the DE Farm Market Directory.

Sara will be providing support for programs being developed by the Fruit and Vegetable Growers Association of Delaware working directly with board members and university advisors. Sara will help with membership outreach and work to increase membership. She will maintain and update the association website, blog, Facebook, and Twitter pages and assist in publishing an association newsletter. One of Sara’s main jobs will be to coordinate a FVGAD initiative to promote vegetable and fruit consumption in Delaware and promote locally produced vegetables and fruits. She will be promoting vegetable and fruit consumption around the state at public events targeting parents. Sara will also be offering support to direct marketers in Delaware who offer school tours on produce farms with educational programs about vegetables and fruits that are age appropriate.

Sara will also be conducting programs in elementary schools to educate about the importance of eating fruit and vegetables and on what produce is grown in Delaware. She will also provide education based on farm to school programs emphasizing the health benefits of the local produce being supplied to schools and will offer support school garden initiatives with educational programming on the benefits of growing and eating produce. She will also assist with grower workshops on producing for and selling directly to schools, colleges, institutions, and restaurants.

In addition, Sara will be assisting with outreach on produce food safety, Good Agricultural Practices (GAP), and Good Handling Practices (GHP), by working with farmers to develop finished farm food safety plans and prepare for audits. She will set up sessions for food service managers to better understand produce food safety and GAP’s.

Sara will be out and about visiting many DE produce growers in the coming months to learn more about the produce industry and to develop ideas on how to best promote DE grown fruits and vegetables. Please welcome her to your farms and businesses.

Water Testing for Produce Food Safety and Third-Party Audits, DPHS Lab Agrees to Do Testing

Friday, April 8th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist;

Water testing for microbial indicators is a recommended Good Agricultural Practice (GAP) for irrigation water and Good Handling Practice (GHP) for packing house water and is part of a produce food safety plan. It is a common requirement of third party GAP and GHP audits.

Water testing should be done yearly. For wells used in packing houses, samples should be taken just prior to the packing season. For irrigation wells, samples should be taken at the beginning of the irrigation period. For irrigation using surface water (ponds, streams, rivers, ditches), it is recommended that water be tested at the beginning of the irrigation period and just prior to first harvest.

For all sources, water should be tested for generic E. coli, the indicator bacteria for fecal contamination of water. For irrigation water, test should be done in a way to quantify bacterial levels (numbers of bacteria in the sample).

For packing houses, the water should be potable (same as drinking water) and should have no E. coli.

For irrigation water, current guidelines are that the samples where water will contact the harvested part of the vegetable or fruit should be less than 126 CFU (colony forming units) or MPN (most probable number of bacteria) per a 100 ml sample. For crops where there will be no foliar contact the sample should be less than 576 CFU (or MPN)/100 ml. Sources over these levels should be evaluated for sources of fecal contamination (livestock, wildlife, sewage).

A MOU (memorandum of understanding) is being finalized between the Fruit and Vegetable Growers Association of Delaware and the Delaware Public Health Service Laboratory to do water testing for Delaware produce growers. For wells with potable water where presence or absence of E. coli needs to be tested, the cost will be $2.00 per sample. For irrigation sources where numbers of E. coli need to be determined, the test will be $18.00 per sample. Details of the program are being worked out and the program should be up and running within 4 weeks.