It has been estimated that annual losses of stored grain damaged by insect infestation, heat, molds, fungi (mycotoxins), and bacteria are approximately equal to the annual grain loss arising from crop pests during the growing season. A 1990 survey conducted in the U.S. estimated the stored grain losses for the year to be over $500 million. Typically about 5-10% of the world's food production is estimated to be lost each year because of direct or indirect insect damage to stored grain supplies. The increasing world population places an ever-increasing strain on the world supply and production of foodstuffs, and as such, increases the urgency to identify and implement processes that can reduce or mitigate losses of stored food supplies, such as stored grains.
Efforts to increase education and awareness of proper management and maintenance of stored grain supplies may help to slow or reduce annual grain losses. For example, activities such as regular cleaning and repair of grain storage bins and processing equipment, using residual insecticides in storage areas prior to storing grain, properly cleaning and drying grain prior to storage, proper aeration of stored grain, and regular inspection of the stored grain can help prevent and control damage to stored grain. Nevertheless, these activities may not be sufficient on their own to mitigate loss and so, in addition to these activities, a number of fumigation methods have been developed. Older fumigation methods treat stored grain through the application of toxic chemicals such as phosphine and methyl bromide to the stored grain. While such methods can kill insects, they may not be effective in treating mold, fungus, and some bacteria, and they may present a health risk to people who may come in contact with the chemical agents. Furthermore, since the ratification of the 1987 Montreal Protocol, an international treaty designed to phase out substances identified as having a role in ozone depletion, methyl bromide is no longer available for use.
Ozone has been shown to be an alternative to the more toxic chemical fumigants in treating grain for fungus, mold, bacteria, and insects. Some methods for grain decontamination that incorporate ozone may seek to expose the grain to a high concentration of ozone for an extended period of time, and may incorporate fans or air movement systems. Other methods utilize a conveyor belt to pass grain through an atmosphere containing ozone. Some of these methods provide a treated product that is not compromised in safety, quality, or taste; however the ozonation methods may be slow and may have a limited ability to decontaminate large volumes of grain in a reasonable amount of time.
The present disclosure provides an apparatus and related methods that comprise a pressurized ozone chamber that can decontaminate grain in less time with increased exposure rate and increased capacity to move large volumes of grain through the decontamination treatment.