by Katie Navarra
The efficient flow of wash-pack zones is a post-harvest necessity. On Aug. 1, the University of Vermont (UVM) and the Cornell Cooperative Extension of Eastern New York (CCEENY) invited local producers to discuss post-harvest handling challenges and considerations when planning wash-pack zones. Paul and Sandy Arnold of Pleasant Valley Farm in Argyle, NY, hosted the event and offered a walk-through of their post-harvest process.
“Fresh produce is still alive. It perspires, giving off ethylene, and it releases heat,” said Chris Callahan, Extension associate professor of agricultural engineering at UVM. “Sometimes we only think about harvest on a hot day, but fresh produce releases heat. It loses moisture, can get sick and even die once it’s brought in from the fields. Post-harvest is not a hospital. Produce will not get better, only worse.”
Creating a post-harvest process and space that considers what happens to produce after it’s picked is critical to increasing shelf life and reducing the risk of contamination. When a post-harvest process thinks through what happens to produce after its harvested, food safety will follow.
“You are already 95% of the way to food safety if you have a system that’s clean and efficient,” Callahan said.
“Risk reduction isn’t rocket science, but farmers do have an obligation to think it through and take steps to limit chances for contamination,” said Hans Estrin, Produce Safety Accreditation Program coordinator at UVM.
Estrin encourages growers to look at every potential contamination source. That includes people (farm owners and workers), soil, water, animals (wild and domestic), buildings, equipment and tools. For example, produce farms that also raise livestock need to think about placing pastures in areas where runoff won’t carry water into vegetable fields.
“Don’t freak out,” Estrin said. “Integrate food safety into your whole process to reduce risk. Remember that bringing clean, healthy produce to market is what we’re after.”
Creating conditions that inhibit bacterial growth is equally important. Drying produce, limiting the time it is out at higher temperatures and making sure edible foods aren’t around the work area are simple steps any farm can implement.
“Every 10 degrees the produce is cooled brings down the bacteria count,” Estrin said. “Someone can eat one or two bacteria and probably be okay. Eating tens, hundreds or thousands will probably make someone sick.”
While food safety is critical, taking steps to remove moisture and cool produce has added benefits. It increases shelf life and makes life livable and sane for the farmer, Estrin added.
Andy Chamberlain, agricultural engineer at UVM, stresses the importance of using the “Principles of Lean.” These principles are often associated with lean manufacturing, but it’s not about doing more with less. It’s about identifying the farm’s value and what the customer wants. Anything (process or product) that doesn’t contribute to that is eliminated because it’s waste. This applies to all aspects of the farm, but the workshop focused on what that means for post-harvest processes.
“It’s important to create a flow that avoids interruptions, delays and bottlenecks,” Chamberlain said. “This is where the majority of waste can be eliminated.”
A smooth, single pass flow of product in one end and out the other of a packing area minimizes waste, he explained. It doesn’t have to be linear; a U-shape can be as effective, but a criss-cross, zig-zag pattern slows the process down.
At the Arnolds’ Pleasant Valley Farm, produce is harvested using three golf carts. The root vegetables come in one end, passing through a barrel washer. The greens are brought in through a separate entrance and washed in a bubbler and spun in a washing machine. The Arnolds have a sophisticated wash-pack setup that has evolved over the years. Callahan emphasized that setting up a clean, efficient work area can be done at on any budget.
“The post-harvest packing can be in an open area using sheep watering tanks,” he said.
The UVM team recommends sheep watering stock tanks rather than black rubber tubs because the gray stock tanks provide more visibility. It’s more obvious when the water is dirty and needs changing. However, the shallower tanks can be difficult for washing some crops like kale.
Some farms use 55-gallon drums cut in half and set on stands underneath a water spigot. Others place old bath tubs on stands at the edge of the field. The key is not necessarily the equipment itself, but that it’s clean and the process is designed to be efficient and reduce risk.
“When you’re just starting out, think about proficiency and flow,” Estrin said. “You don’t have to have a lot of money. The washing and packing can even take place in your kitchen if you’re just starting out.”
To find ideas for establishing an efficient post-harvest packing process on your farm, UVM offers multiple blogs, examples and videos of other farms as resources. Visit go.uvm.edu for more information.