Worried about mold and pests in stored seeds and grains? Just chill

Brazilian-based Cool Seed is bringing its experience in chilling stored grains and seeds in grain bins and warehouses to the United States market. Cool Seed’s U.S. sales and operations manager, Eric Henlon, said Cool Seed’s post-harvest storage technology provides significant benefits in controlling insects and mold for a variety of grains and seeds—without chemicals.

“Given that grains are a living product, they breathe, produce carbon dioxide, consume water, oxygen, develop heat, and therefore lose weight,” Henlon said. “Grain stored at higher, warmer temperatures produces a quantity of heat, carbon dioxide and water loss much greater than grains stored at cooler temperatures.” Henlon says post-harvest losses occurring at the drying, storage or milling stages of the crop can reach rates as high as 30 percent of the total harvested.

Carlos Campabadal, an instructor/IGP Institute outreach specialist at Kansas State University, told High Plains Journal that current awareness among U.S. farmers of seed- and grain-chilling technology is not high. Henlon concurs: “I have had quite a few conversations with grain elevator people, farmers, etc., and if you ask 100 people here if they have ever heard of grain chillers about 90 to 95 have never heard of it.”

Seed and grain chilling technology is more widely used in tropical countries like Brazil and Thailand, where seed and grain deterioration can happen much more quickly than in cooler climates, and where there is often less acceptance of using chemicals to retard spoilage. Campabadal, whose doctoral research project was on non-chemical means of preserving grains and seeds, conducts research and performs consulting work on this topic in many countries.

He says that while U.S. farmers do not apply as many chemicals to preserve grains and seeds as is sometimes believed in other countries, seed chilling—as opposed to drying, which also cools to some extent—is not widespread here.

“Grain-chilling has been in the U.S. at least since the 1990s but has not been picked up. Recently tech companies have been pushing it [in the U.S.] more aggressively,” he said.

So what has been holding seed- and grain-chilling back among U.S. farmers: cost or the “It’s always been done this way” syndrome?

“A little of both,” Campabadal said. “Grain chillers can be expensive machines,” so it may be the processors and grain storage facilities that show more interest, he said. The climate is also partly responsible. “Most grain is harvested in the fall, when it’s already cool,” Campabadal said.

Henlon says Cool Seed is the only company that offers the seed industry a specialized grain bin to chill seed before it is bagged and stored, to preserve and maintain seed quality from the time immediately after harvest and conditioning and onward.

Cool Seed’s bin for dynamic cooling is available in 5- to 30-ton capacity sizes, can be operated automatically or manually, and works in conjunction with a Cool Seed chiller unit to chill the seed as it descends inside the bin. It cools it to around 60 to 65 degrees F for loading into bags for warehouse storage.

The dynamic cooling method using the SRF bin cools seed quickly in a more integral, efficient way, Henlon says, versus the typical procedure of sending seed bagged at warm temperatures to be stored in a refrigerated warehouse. Henlon said this delay can result in a prolonged time for the bagged seed to reach a sufficiently cool temperature level—a length of time that can negatively affect its quality, germination, and vigor. 

Southern growers could benefit

Which grains or seeds can benefit the most from this technology? Campabadal sees seed-chilling as being attractive for higher-moisture grains cultivated in hotter climates. Rice-producing states like Arkansas, Louisiana, South Carolina and California should be very interested, he said.

In some parts of the Midwest, hard red winter wheat is harvested in late June or early July, when hotter temperatures accelerate the growth of insect pests and mold. Wheat farmers and processing facilities already use blowers to cool and dry stored wheat in order to bring its moisture level down from 18 to 22 percent to no more than 14 percent. Chillers could bring benefits.

“Chilling will play a big part in the organic market, I think,” Campabadal said. “And maybe as awareness grows, consumers will come to demand it, too.”

Cool Seed started in 2001 in southern Brazil and its current headquarters is in the same region in Santa Tereza do Oeste, Parana state. According to Henlon, “Cool Seed products are of a very robust and rugged construction that reflects their development and design of needing to be able to function in severe conditions of heat and humidity that are found in Brazil and South America, an area in which the European units are lacking due to the less severe climatic conditions of their countries of origin.”

Cool Seed has developed three categories of products.

From the beginning, the company marketed grain cooler/grain chiller units for cooling the temperature of stored grains and seeds in grain bins/grain silos.

The company has developed additional products such as the UTA Air Treatment Unit and SAX Axial Flow Dryers for application in several agriculture sectors for drying temperature sensitive products.

Around 2004 it developed what it calls Dynamic Artificial Cooling (unique to Cool Seed) to address what it considered a drawback in the transport and storage flow. The process involves a chiller unit and a specialized grain silo/bin (model called SRF) inside the seed plant to chill seeds before they are bagged and stored in warehouses. The company says this was developed because the seeds, harvested in warm conditions and then cleaned and dried to reduce their humidity, were being bagged and stored in a warehouse in stacks which created a warm grain mass, making it susceptible to insect and mold infestation.

“Many people think wrongly think Cool Seed’s approach is unnecessary, since they will tell you that they store their bagged seed in a refrigerated warehouse, which may be true,” Henlon said. “However, by placing the warm, bagged seed directly into a refrigerated warehouse in stacks again, this creates a grain mass that retains its heat, due to seeds and grains being great insulators—despite being in refrigerated conditions—for up to several weeks during which time you can have problems develop with mold and insects.” 

Nuts and bolts of a chiller

A Cool Seed chiller unit consists of a high-capacity, industrial air conditioning unit (mobile or stationary models) that produces dehumidified, very cool air (about 50 degrees F) that it blows via insulated tubing into either a grain bin/silo or an SRF dynamic artificial cooling bin/silo.

The unit is connected with insulated tubing to a grain bin/silo via an aeration fan opening to blow the cooled air in to the stored commodity, leaving bin roof vents open. Over a period of up to several days (time depends on size of grain bin) cooler air displaces the warmer air out the vents to achieve a uniform cool temperature throughout the stored grain mass. Once the desired cooled temperature is obtained, the vents are closed, the fan opening is closed and the stored commodity can remain in the bin for up to several months and will retain that temperature due to the thermic properties of grains and seeds as great insulators, the company says.

“The effect of the cooled air on insect and mold development is that, once the grains/seeds are cooled to some point in a range of 59 to 68 degrees, you will greatly slow the development and reproduction of insects and molds, thereby inhibiting them from becoming an infestation down to completely stopping their activity,” Henlon said.

He adds, “Insects don’t like cold, and in a cold or colder environment they go into a sort of hibernation known as diapause in which they significantly reduce their activity, I guess it is sort of a reflex behavior they have as they ‘wait out’ the cold hoping that it will warm up.”

Campabadal believes that encouraging overseas customers in tropical markets, like Malaysia and Indonesia, to increase their use of grain-chilling technology could have benefits in opening them up to more imported U.S. grains like corn. “U.S. corn is softer than South American corn, with somewhat more moisture,” he said. “Some importers in tropical countries are reluctant to import North American corn for that reason, because it’s harder to store properly in those hot climates.”

He notes that containerization of export grains stands at about 5 percent right now. “Southeast Asia gets back lots of empty containers; those countries would like to see them back-filled with U.S. grains.”

David Murray can be reached at [email protected].