Today's consumers expect a high-quality, consistent product. Much of the quality depends on the grain received from the grain farmer, but a surprising amount of a consumer's satisfaction depends on how the product is stored. To produce a good bowl of popcorn, the popcorn grain must be maintained at the correct moisture content. Too much moisture and the corn will begin to mildew and deteriorate; not enough, and the corn will not pop correctly.
Popcorn grain has conventionally been stored in bins with fans to provide conventional aeration; however, this method has several drawbacks. Because the aeration fans use outside air, the temperature and humidity of the air being used depends on outside ambient conditions. Hot, humid air in the summer and cold, dry air in the winter are not conducive to the stable temperatures and relative humidity needed for best storage practices. As a result, the popcorn has a shorter storage life, more grain fracture, increased spoilage, unacceptable levels of insect infiltration, and a lower popping ratio.
To meet the design criteria, Brainard decided to use a 30-ton industrial air conditioning unit, the THPAC-30 model, with 20 kW of electrical reheat. Tempered air was introduced into the bottom of the bin, and the high static blower on the air conditioning unit was able to circulate the air throughout the bin (figure 1). To monitor for consistent temperature, probes were placed at different depths within the filled bin (figure 2). The moisture content was determined by testing core samples taken from different depths within the bin. Prior to introducing the tempered air, Temp-Air determined through testing that the average temperature of the corn in the bin was 68.9oF (20.5oC), and the moisture content of the grain was 14.3 percent. After 96 hours of operation, the corn was at 55oF, and the moisture content was at the optimum 13.5 percent (figure 3).