Grains and other similar commodities are dried by purging air from the environment through a silo filled with grain or any similar product. Traditionally, most of these systems utilise large fans to introduce outside air through the bottom grid of the silo into the stacked product and thereby provide the necessary drying. Due to the high-velocity air intake through these fans, dust is also entrained into the product causing a distinct decrease in quality.

The conventional silo drying method is also open to the environment, and therefore severely affected by inclement weather. Silo drying in humid environments can also cause spoilage of the product. This method is an uncontrolled process with temperature and humidity fluctuations which may cause inconsistent drying and negatively impact the final product.

To eliminate the effects of fluctuating weather and accelerate drying, heat is usually introduced into the process. With heating, there is the risk of stress fractures in grain products. High-temperature drying is also known to cause enzymatic browning, which causes unpleasant odours and flavours in for example nuts. Heat can contribute to discolouring and cell damage in certain products which should be avoided at all cost, especially for the export market. Another adverse effect of high-temperature drying is the compromising of the nutritional content. Fast, high-temperature drying of macadamia nuts may cause early separation of the nut from the shell, which may result in bruising or even breaking of the nuts during handling and processing. For this reason, it is recommended in the industry that nuts such as macadamias rather be “cured” than dried.