Written collaboratively by Rhoda Burrows, Professor & SDSU Extension Horticulture Specialist and Jennifer Folliard, former SDSU Extension Family & Community Health Field Specialist.
Why is Food Safety important?
Food safety is an important issue at farmers markets. Customers expect the food and products they purchase to be grown and handled so that they will be safe to consume. Vendors have a responsibility to grow and handle food using good food safety practices.
The Centers for Disease Control and Prevention (CDC) estimates that each year roughly one in six Americans contract a foodborne illness. Over 4 million get food poisoning from produce. Of those who get sick from contaminated produce, on average, 22,000 are hospitalized and 360 die (1).
From 2009 to 2015, 23% of the deaths and 34% of the illnesses each year from foodborne disease were attributed to contaminated produce (1). Melons, lettuce, cucumbers, spinach and tomatoes have all made news headlines for causing illnesses in recent years, but any produce has potential to become contaminated.
These statistics substantiate the importance of food safety. In order to produce and sell safe foods, growers must strive to understand and implement the best food handling practices at each stage of production, processing and marketing.
Health, Hygiene and Hand Washing
Health, hygiene and hand washing apply to all stages of production, processing and marketing. Ill food handlers can easily contaminate fresh produce with disease-causing microorganisms. Many of these organisms have the ability to survive on fresh fruits and vegetables for an extended time, from several days to weeks. Once the organism is established on fresh produce, it is very hard to remove. If a vendor or employee is sick, they should not handle food, food products, utensils, containers and other types of food contact surfaces. The following symptoms are indicative of a foodborne illness and necessary precautions should be followed to not contaminate produce:
- Diarrhea, fever, vomiting, jaundice or sore throat with fever.
- A cut containing pus, such as a boil or infected wound that is draining and located on the hands, arms, wrists, or a body part that is not covered.
- If the employee has been diagnosed with a foodborne illness or lives with someone that has been diagnosed with a foodborne illness.
The manager will make the decision to send the employee home or restrict the jobs that the sick individual performs that day.
Open wounds can harbor disease-causing microorganisms. If the wounds cannot be covered adequately with a bandage or glove, the field worker should not be handling fruits and vegetables or food contact surfaces, such as containers. Duties that do not involve contact with or close proximity to foods and food contact surfaces are recommended.
Good personal hygiene should also be practiced. Be certain to change out of any clothing worn in animal production areas before working with produce. Farming and growing produce can cause workers to become dirty, and it is important to clean up before attending the market and selling produce.
Hand washing is an important part of food safety. Vendors should wash their hands in the following situations.
- Harvesting, picking, packing, transporting, bagging, displaying or otherwise handling fresh produce.
- Putting on single-use gloves.
- Preparing foods on-site.
- Presenting a cooking demonstration.
- Preparing food samples.
- Handling ready-to-eat products.
- Touching and feeding animals.
- Going to the bathroom.
- Coughing or sneezing.
- Eating or drinking.
- Handling dirty tools or equipment.
- Handling money.
Glove Use at Farmers Markets
Many people assume that wearing disposable, single-use gloves prevents contamination. However, gloves can transfer harmful microorganisms to produce just as easily as bare hands can. Correct use of gloves maintains the safety of harvested fruits and vegetables. Be sure to wash your hands and bandage cuts before putting on gloves and when changing to a fresh pair. Then, wash your hands after removing gloves. Never wash and reuse single-use gloves. Food handlers should change their gloves in the following situations:
- If the gloves become torn.
- Before beginning a new task.
- If a task is interrupted. For example, by answering the telephone, gathering supplies, assisting with the cash register, handling money, or emptying trash.
- After two hours of continual use.
- If the gloves are contaminated. For example, sneezing
- When the food being handled changes from raw to cooked or ready-to-eat.
- When leaving the food preparation and serving area.
There are many situations and times when a grower should wash their hands. However, while working in the fields or at the farmers market, growers may find that there is no sink or running water available. Hand sanitizers and moist towelettes do not replace the need for hand washing. These products are not effective in removing bacteria when debris such as food particles or dirt are on hands. Hand sanitizers should not be used in place of good hand washing. To overcome the lack of hand washing facilities consider building a temporary hand washing station.
Building a Hand Washing Station
Farmers markets or individual vendors can build their own, simple hand washing station when one is not available. A hand washing station should be easily accessible for all food handlers on site. For more information on building a hand washing station for use at a farmer’s market, food stand or in the field refer to the University of Minnesota’s On-Farm Handwashing Important for Food Safety website.
Proper Hand Washing Steps:
- Wet hands with warm water from spigot.
- Apply soap and rub for 15 seconds.
- Rinse hands using water from spigot to remove all soap.
- Dry with a paper towel.
Safe Food Handling: Growing and On-Farm Production
Growers producing local foods are responsible for the products they grow for sale. Using Good Agricultural Practices (GAPs) while the crops are growing in the field includes precautions such as the proper use of manure and water sources. Additional components of a safe food-handling plan include restricting access by pets or wild animals, and cleaning equipment before use.
Water Source and Flooding Considerations
Clean water is crucial to safe food production. Once contaminated water is applied to a field, E. coli and other harmful bacteria can persist for over six months in the soil and on plants. Whatever the water source, remember to add a backflow preventer to irrigation hookups.
Surface Water Considerations
Surface water can become contaminated by farm animals, wildlife, run-off during storms, flooding, leaking or overflowing septic systems and manure piles. Therefore, surface water should only be used as a last resort, and it should be tested at planting, peak use, and prior to harvest. Minimize the contact of surface water with the edible portion of plants by using drip system, or, for orchards, low volume spray technique. A drip irrigation system is mostly preferred with a subsurface application, or under plastic mulch. Overhead spray methods are considered high risk for causing contamination.
Municipal Water Considerations
Municipal water is considered the safest water source since it is potable (safe to drink) and adheres to strict chemical and microbiological standards. The South Dakota Drinking Water Program, part of the Department of Environmental and Natural Resources (DENR), develops and enforces the South Dakota Drinking Water regulations that apply to public water systems in the state. Additionally, chlorine and fluoride from municipal sources are at concentrations low enough not to interfere with plant growth.
Drinking water contaminants, compliance reports, and violation history of public water sources across South Dakota can be viewed at the DENR’s drinking water webpage. Additionally, a DENR Proof of Safety may be furnished through a water bill or by request. To contact the DENR Drinking Water program visit the program website or call 605-773-3754.
Well Water Considerations
If well water is being used, have it tested at the beginning of the season before the first irrigation application, and every three months thereafter. FSMA Produce Safety Rule stipulates that the well should be tested 4 times in the initial year, and if acceptable, the well can be tested annually afterwards as long as tests continue to be within guidelines. Visit the Produce Safety Alliance website for more information. The test is for E.coli specifically, rather than for generic coliform bacteria counts. Wells can become contaminated by flooding or heavy rains, or if located close to a cesspool, septic system, livestock agricultural site, manure storage area or drainage field. Properly maintaining a well includes conducting wellhead inspections to check the condition of the well covering, casing and cap to be sure it is in good condition. There should not be any cracks or entry points for potential contaminants. In addition to regularly scheduled testing, wells need to be tested if at greater risk of contamination; for example, after a flood or unusually heavy rains. Note any changes that occur in the water quality such as cloudiness or grit: these may indicate surface water is contaminating the well. If you notice these changes, have the water tested again.
Flooding of production fields is particularly hazardous. Flood water may deposit contaminants such as chemicals and pathogenic microorganisms onto both the soil and plants. Because of the wide variety of possible contaminants and their erratic occurrence, testing is generally not a viable option. One needs to assume that contamination may have occurred and manage the affected area accordingly. It should be noted that pooled water, which is the simple accumulation of water within a field following a rainfall, is not considered flooding. The FDA has developed specific guidelines for fields affected by flooding. The FDA considers that produce directly contacted by flood waters is adulterated and cannot be sold or used for human food. See the Produce Safety Alliance’s Food Safety for Flooded Farms publication for more information.
Safe Food Handling: Harvesting and Storage
Keep harvest records by recording the following information: what type and quantity of produce was harvested; field location; who harvested which produce; and the date of harvest. These records can be valuable for recording the productivity of the fields throughout the season as well as tracing produce that may be implicated in a foodborne illness. A system for marking containers of harvested produce with a tracking code that contains this information can also prove helpful if a problem develops. For more information visit the Cornell website.
Best Practices for Use of Produce Containers
When harvesting, growers should pay special attention to preventing contamination, avoiding contact with soil, and selecting proper container types. Cleaning and sanitizing equipment is also an important part of harvesting and storing produce. For more information on produce containers, refer to the Louisiana State University Extension article on Best Practices to Ensure On-Farm Food Safety.
Managing produce quality
Produce with damaged surfaces (cracks, cuts, rots, bruises, etc.) should be culled, because these injured areas can serve as entry points for harmful microorganisms. These microorganisms can then be transferred from the damaged produce to high quality produce. To reduce cross-contamination it is best to pick the blemished produce in a separate harvest operation. These culled produce items should not be piled within the field, because this can attract insects and animals that carry harmful microorganisms, a situation that has been implicated in the incidence of deadly disease outbreaks. Instead, dispose of culled produce in a location that is not near the growing, processing, or storage areas.
Local and national surveys indicate that produce quality is the number one reason customers come to a farmers market. This is yet another reason why defective produce should be culled and disposed of, not sold. Undamaged lower quality produce, such as misshapen items, should at the very least be separated and sold separately. However, marketing lower quality produce can have a negative influence on your customers’ perception of your produce. They may decide that all of the produce at your market is inferior. Rather than market your lower quality produce a better option may be using the produce in a processed product or donating it to the local food bank.
Cleaning or Washing Produce
If produce appears clean, don’t wash or rinse it, as that can introduce or spread pathogens between items. Explain to your customers that they should wash it just before use. However, if needed after harvest, excess field dirt and plant debris can be removed from many types of produce by gentle scrubbing with a dry brush. Be sure to clean the brushes frequently and use a tarp or container to catch the dirt so it does not contaminate the processing area. It is recommended to use this method of dry brushing when possible, rather than washing, before packing or marketing fresh fruits and vegetables. However, very muddy produce or produce that cannot withstand brushing may require washing with water.
Understanding contamination from water
Washing with water must be done carefully, as it has the potential to lower the quality of the produce and cause contamination. Although washing with water is typically a good food safety practice by the consumer just prior to consumption, when preparing produce for sale it can increase the risk of contamination. Water can infiltrate to the inside of the fruit or vegetable through the following process. When produce is placed in a container of water that is at a different temperature than the produce, this situation is called a temperature differential. If the water is colder than the produce, it causes the air in the cells of the fruit to contract. This contraction draws water into the fruit or vegetable through pores, channels, or bruises. The water drawn into the produce may be contaminated, thus causing the produce to become internally contaminated.
In some instances, washing produce may be required. Growers often look to various methods of washing fresh produces before selling it to customers. There are several questions to consider:
- What is the possibility that the produce was contaminated?
- Should this specific produce be washed and how should it be washed?
- What is the water source - is it a public treated and tested source or a private well that requires sampling sent to a state health lab for testing? Water that contacts produce after harvest must be potable, with zero E coli present.
- What temperature should the water be?
- Should I use a sanitizing solution?
The following procedures provide tips and best management practices for washing specific produce items without causing contamination or lowering the quality or appearance of the produce (6).
For more detailed information, view the SDSU Extension article, Food Safety Rules for Fruit & Vegetable Growers: FAQ.
Melons & Cantaloupe
Melons have several qualities that make them more susceptible to contamination than other fruits and vegetables including:
- Warm weather growing conditions are favorable for the growth of human pathogens such as E. coli, Salmonella, and Listeria.
- Direct contact with the soil and heavy rains may increase the risk for contamination.
- Netted rinds provide a good area for human pathogens to survive, and the removal of pathogens is more difficult than with smooth surfaced produce.
- When harvested, scarring occurs around the stem. This can serve as a route for infiltration of pathogens.
- Watermelons and less mature cantaloupe are sensitive to injury when chilled, therefore increasing the likelihood of storing at ambient temperatures that encourage the growth of microorganisms.
- Melons are heavy and difficult to handle which contributes to more damage.
All of these reasons contribute to the fact that melons have repeatedly been associated with foodborne illnesses.
In order to prevent contamination, follow these procedures:
- Follow all recommended food safety field practices. Drip irrigation is recommended. Watch for field incursions by wild or domestic animals, and do not harvest any melons within five feet of any animal droppings (this distance may need to be increased if heavy rains have spread the contamination.) Flagging contaminated areas is recommended to help harvesters avoid them. Train all field staff in food safety hazards and procedures, including hand-washing.
- Clean and sanitize all containers, shipping, and storage surfaces. Do not transport in an unwashed truck bed. Clean padding can be used to reduce bruising and abrasions.
- If necessary, clean with soft dry brushes. Provide customers with safe handling and preparations instructions for cantaloupe. For more information on reducing food-borne illness risk with cantaloupe, see the FDA’s Commodity-Specific Food Safety Guidelines for Cantaloupes and Netted Melons publication.
To maintain quality, leafy greens are often sprayed with a light mist when harvested to reduce the loss of water. This must be an approved water source and the method used for spraying must not introduce additional contaminants. When possible, harvest early in the morning as the produce will be cooler and better hydrated.
When greens and other crops are harvested they need to be cooled quickly to maintain quality and safety. Consider the following precautions to reduce the risk of contamination of leafy greens and other produce:
- Do not use water that is more than 10° F colder than the produce, this can allow for infiltration of water into the plant. Never wash with water that may be contaminated with pathogens.
- Always clean and sanitize harvest and wash equipment before using it for leafy greens.
You should use several washings after harvesting leafy greens and other crops. Start with water that is slightly cooler (less than 10° F) than the produce and progressively use colder water in subsequent washings. This will help cool the leafy greens and safely maintain quality. Studies at the University of Vermont have found that using three consecutive rinses (with fresh water each time) or a single rinse with sanitizer drastically reduced the amount of E. coli remaining on lettuce leaves.
Another option is to use a pass-thru system, where the greens are spread on clean mesh trays that allow quick drainage and are sprayed with fresh clean water rather than submerging the produce in a water bath. It may be necessary to stir or turn the greens several times so that all surfaces are cleaned.
After cooling with water, place leafy greens in a refrigerator to maintain a temperature of 32 to 36° F. The refrigeration unit must be kept clean. Do not store leafy greens in a closed container with other fruits or vegetables that produce ethylene gas, such as apples, tomatoes, bananas, mangos, onions and pears. Ethylene gas can cause browning and an off taste in lettuce and other greens.
High humidity (90 to 95%) needs to be maintained to minimize wilting. Avoid direct contact with standing water, which can serve as a source of cross-contamination. Clean, moist (not soggy) paper towels can provide sufficient moisture if coolers are not equipped with humidifiers.
At the market, use tongs or disposable gloves when bagging leafy greens for customers. Avoid setups that allow customer’s hand to touch raw produce.
Information on these and other crops can be found at the FDA’s Produce & Plant Products Guidance website under the heading “Industry Guidance in Collaboration with the FDA.”
Packaging, Transportation & Storage
All packaging materials should be made of food contact grade materials. Products that are not food grade may contain toxic compounds that could leach out of the packaging materials and into the produce. Empty packages such as boxes and plastic bags should be stored in an enclosed area to protect from insects, rodents, dust, dirt and other potential sources of contamination. This will protect against losing valuable materials and preserve the integrity and safety of the packaging materials.
Whenever transporting produce from the field or to the market, ensure that the vehicle is clean and sanitary. If you use a general-purpose farm pickup for transporting fresh produce, thoroughly wash, rinse, and sanitize the bed each trip. This is especially important if live animals or objects of dubious sanitation have been transported previously. During transportation, packaging, and at the market, provide shade for the produce with a clean plastic tarp or other cover to reduce heat buildup and sun scalding.
A variety of facility designs are available for cold storage, ranging from commercial walk-in coolers to farm-adapted designs, or even refrigerated truck trailers. Remember that most coolers are designed to keep cool produce cool, not take out the “field heat” from the produce. Forced-air designs help remove “field heat”, but there must be good air circulation to avoid hot spots that can lead to product deterioration. When possible, harvest early in the day when the produce is still relatively cool.
Rememberthatcropsdifferintheirtolerancetocoldtemperatures;forexample, cucumbers and peppers can be damaged by temperatures under 45°-50° F.
- Dewey-Mattia D, Manikonda K, Hall AJ, Wise ME, Crowe SJ. Surveillance for Foodborne Disease Outbreaks — United States, 2009–2015. MMWR Surveill Summ 2018;67(No. SS-10):1–11.