Post-Harvest Handling Decision Tool > Crop Groups > Beans and Peas
The overriding consideration for the post-harvest handling of beans and peas is rapid cooling. Excessive moisture can promote rapid breakdown, especially with beans.
On large, commercial operations, hydrocooling is common. However, wetting the pods can promote spoilage unless the water is treated to prevent the growth of fungus. A variety of sorting and grading tables are the most common method for grading, since crops tend to be mechanically harvested. Beans and peas are packed into well-ventilated containers, such as wooden crates or mesh bags.
In the Upper Midwest, none of the visited farms used machinery to grade beans or peas. Because all of the visited farms harvested by hand, there was a feeling that quality was close to adequate when product came into the packing shed. Use of hydrocooling versus forced air cooling was independent of the scale of the operation.
Air Cooling
For air cooling, well-ventilated containers are critical. Regardless of the actual harvest containers used—visited farms used five-gallon buckets or plastic-lined bushel baskets—most farms used well-ventilated plastic totes for initial storage in the cooler. Pallet bags or individual bags were added after the initial removal of field heat to preserve humidity.
Hydrocooling
About half of the farms visited hydrocooled beans and peas using a water bath in a bulk tank. Beans and peas were removed from the water bath using mesh bags or ventilated containers. At Rock Spring Farm, a fishing net is used to scoop the last beans out of the tank.
Peracetic acid, as found in the commonly-used organically approved water additive Tsunami 100, has been noted to cause peas to turn rusty. This creates a conundrum for organic growers wanting to use hydrocooling, since moisture on the peas promotes breakdown.
Spin Dry
Since all of the farms visited relied on manual harvest for their beans and peas, sorting needs were limited. The farms that used hydrocooling also use that step for quality control.
At Featherstone Fruits and Vegetables, poor harvest conditions occasionally resulted in a need to conduct more rigorous quality control sorting. To do this, butcher paper of the sort available at an office supply store is rolled out on eight-foot plastic banquet tables. Washed peas and beans are poured out on the butcher paper and moved down the paper by hand. The waxy coating provides a food-safe surface and allows the product to slide easily down the table, where it is re-containerized for cooling.
This information is part of a Post-harvest Handling Decision Tool developed by Chris Blanchard of Rock Spring Farm in Decorah, Iowa. The tool is a project of the Fruit and Vegetable Working Group affiliated with the Value Chain Partnerships program. This project was funded by the Iowa State University Extension Value Added Agriculture program and the Leopold Center for Sustainable Agriculture. Blanchard conducted case studies of three vegetable operations to gather information for this decision tool. Products referred to in this tool are not an endorsement by Iowa State University.