Using a Peanut Drying Monitoring System to Estimate Costs of Nonbeneficial Dryer Operation

Abstract. Presently, the peanut industry lacks a commercially available, industry-accepted solution for real-time kernel moisture content determination during peanut drying. Samples of unshelled peanuts are extracted from the semitrailer by an operator periodically, and the samples have to be cleaned and shelled to determine moisture content. A peanut drying monitoring system that includes a microwave kernel moisture sensor, developed within the USDA ARS, provides a means for monitoring in-shell kernel moisture content in real-time. The system determines kernel moisture content with a standard error of prediction of 0.55% moisture content when compared to the reference oven-drying method. Kernel moisture content and other drying parameters are measured every 12 seconds. During recent peanut harvest seasons, peanut drying monitoring systems were placed in 45-ft drying semitrailers with one system near the front and the other near the back of the trailer. As the peanuts dried, pod and kernel moisture content, temperature of the drying peanuts, temperature and relative humidity of the air exhausted from the peanuts, and temperature and relative humidity of the air being blown into the peanuts were measured in real-time. The continuous data, provided by the monitoring systems, were useful in observing the loss of moisture by the peanuts throughout drying. The data also revealed periods of at least 3 hours in which dryer operation did not result in loss of moisture from the peanuts. Such periods can cause a peanut buying point to accumulate unnecessary expenses in propane and/or electric energy expenses per semitrailer, which can total from $4,000 to $8,000 annually for an average-size buying point.