Fruits and vegetables don’t improve with age after they’ve been picked; their quality can only decline from the point of harvest. As fresh foods are often transported long distances and held for long periods of time, proper postharvest handling and storage are critical to maintain quality and safety.

“Consumers have to be confident their food is safe,” says Dr. Bob Whitaker, chief science and technology officer with the Produce Marketing Association. Promoting that safety should be the main concern on growers’ minds when developing their postharvest processes.

Dr. Bob Whitaker

Dr. Bob Whitaker, chief science and technology officer with the Produce Marketing Association, says safety should be the main concern on farmers’ minds when developing their postharvest processes.
Photos courtesy of the Produce Marketing Association unless otherwise noted.

Another important consideration should be protecting your business. He says, “In today’s world, a recall and people getting sick by consuming a produce item can have a dramatic impact on that particular grower, as well as the entire industry.” Bad news travels fast, so it’s more important than ever that growers and others who work in the food supply chain be aware of what makes food safe and the steps they can take to manage risks.

Just as the produce industry has changed, so have the dangers posed to it, says Whitaker. Organisms associated with foodborne illness have evolved, and awareness of health concerns has grown. “Back in the ’40s and ’50s, people died of stomachaches,” he says. The decline in such problems is due in part to improvements in food handling, like refrigeration. However, dangerous organisms still exist in the water and soil, and some have become more virulent over time. Lengthened supply chains increase the risk of spreading problems widely, and larger farms can mean greater impact when problems occur, but pathogens can contaminate food between the field and the farmstand just as easily as they can contaminate food that’s traveling across the country.

“Growers of all sizes need to evaluate the potential risks for cross-contamination of food with potential pathogens. Water, hands, fertilizers, growing environments and all other areas should be fully assessed to make sure you’re doing what you can,” Whitaker says. Every step of the food chain represents potential risks to be managed, and farms of every size should have a food safety program that they implement daily.

The range of management practice models can easily get overwhelming. Best Management Practices (BMPs), Good Agricultural Practices (GAPs), federal and state regulations, and practices advocated by industry groups abound, so you might have a hard time choosing a single set of standards to follow. Instead of worrying about choosing the “right” one, Whitaker suggests selecting one and getting started on developing a plan based on the suggested protocols. No plan will be set in stone; it can always change and improve as you try to adopt new practices suitable for your operation.

The part of the process that most often gives growers pause is the documentation, but Whitaker says that doesn’t need to be an overwhelming task. “You’re not writing a book – your whole plan is probably a few pages and some checklists on a clipboard.”

Some crops, such as root vegetables and others that grow close to the ground, are dirtier than others and require more scrubbing, while others can simply be wiped or brushed clean.

Whitaker suggests enlisting the help of a specialist, such as a county agent or extension agent, who can help with the development of a plan. Many resources also exist online to assist growers with implementing changes that will help keep their food safer and ultimately open up new markets for them, since more retailers now require documentation of operating practices that demonstrate safety and cleanliness. Most practices that are designed to reduce microbial contamination also help to reduce product loss through spoilage and shrinkage, so taking such steps can also lead to greater profitability for growers.

Ultimately, there is no such thing as eliminating all risk and being able to guarantee that a product is free from pathogens. However, growers can employ certain practices that demonstrate a commitment to keeping their products as clean and safe as possible. While many produce items have specific handling needs, there are some basic, universal postharvest steps for all growers to evaluate and consider.

The goal is to pack and ship produce that is attractive and has been cleaned so as to minimize microbial contamination.

Infrastructure sanitation

Buildings used for postharvest handling should be designed to exclude all animals, including birds, rodents and insects. Each step along the flow of product through the building should move the produce to a cleaner area than the one before to avoid recontaminating something that has already been cleaned.

Machinery and tables should have smooth surfaces, such as stainless steel, to avoid catching and harboring microorganisms, and they should be cleaned and sanitized regularly with approved food contact cleaners. Machines with moving parts should be maintained with food-grade lubricants.

Adequate lighting is important. It should allow workers to thoroughly examine each product, and all light fixtures should be shielded to avoid broken bulbs around food products. Keep exposed overhead plumbing and ductwork to a minimum and clean it often. Cleaning supplies should be kept in rooms separate from where food is handled.

Worker hygiene

All workers should be trained in basic personal hygiene and sanitary practices. Their outer garments should be clean or covered with an apron, and they should not wear loose jewelry. They should not eat, drink or smoke inside a processing building, and hairnets and beard covers should be worn when handling produce. Workers who are ill should be excluded from processing until they’re healthy.

Workers should wash their hands before starting work; after every absence from their workstation; after eating, drinking or smoking; or any other time their hands are soiled from contact with anything other than the food they’re working with. Bathroom doors should not open directly into rooms where food is processed and packed, and they should have soap, clean running water and disposable towels.

Cleaning and sorting

Ideally, crops should be washed, rinsed and sanitized as soon as possible after harvest. The goal is to pack and ship produce that is attractive and has been cleaned so as to minimize microbial contamination. Customers look for foods that are ready to eat, so all produce should be free of visible soil. Items that are out of grade, bruised, insect-damaged or otherwise compromised should be culled so they don’t contaminate other items or reduce their shelf life.

Some crops – root vegetables and others that grow close to the ground – are dirtier than others and require more scrubbing, while others can simply be wiped or brushed. Throughout the postharvest process, crops should be handled gently to avoid bruising and cracking.

Water used for cleaning crops should be tested regularly to ensure that the water itself is free from contaminants, and it should be flowing or changed regularly. It’s possible for bacteria to enter produce during the washing process, particularly around the stem scars, but keeping water cold helps to prevent this.

For crops where a diluted sanitizing solution is also recommended, there are many products available, including chlorine, iodine, hydrogen peroxide and other commercial products. Be sure to use only products that are approved for food contact and follow instructions for concentration levels.

All workers should be trained in basic personal hygiene and sanitary practices.

Packing

All equipment should be cleaned and sanitized often. All containers and tools that come into contact with produce must be made of food-grade materials, and empty containers should be stored away from potential sources of contamination. Packaging should be appropriate to the specific item, particularly in that it should be designed to protect the produce from damage.

Cooling and storage

Proper cooling and storage is critical for extending the shelf life of produce, and bacteria will grow on wet products if they are not cooled quickly. For best temperature control, crops should be harvested in the morning when still cool (precoolers that can be used in the field are available for some crops), kept out of sunlight, brought indoors and through the process rapidly, and moved into a cooler quickly.

Temperature and humidity in storage should be monitored and recorded regularly. Refrigerated rooms should have forced air cooling systems for best results; storage racks should be away from walls for better air circulation; and walls, ceilings and floors should all be washable. Nothing should be stored directly on the floor.

Proper storage temperature depends on the crop (see http://post http://harvest.ucdavis.edu/producefacts for details). Most crops are stored at 41 degrees Fahrenheit to best inhibit bacterial growth and retard respiration rate in order to retain flavor and nutrients. Some crops, like basil, tomatoes, eggplants and peppers, will lose quality below 55 degrees Fahrenheit. Others, such as pumpkins and sweet potatoes, need a period of curing before cooling.

Some products benefit from being packed in ice, while others can be damaged by the practice. Maintaining particular humidity levels is also important in the cooling process in order to retain the produce’s water content.

Inventory should be handled on a first-in, first-out basis to help prevent waste and spoilage.

Transportation, distribution and display

The risk of microbial contamination continues during transit. Vehicles should have temperature controls and monitors, all food contact surfaces should be cleaned regularly, and all shipped product should be coded for traceability.

When displaying produce for sale at a farmers market, food should not be put on the ground, and it should be under cover to avoid direct sunlight and contamination from birds.

Winton Pitcoff is a freelance writer based in western Massachusetts.