Effects of different drying techniques on physical chemical and toxicologic properties of maize

Maize is the most widely produced crop in the world and has to be stored under 13% moisture level for safety reason. It is generally harvested at approximately 17-18% moisture level and dried in hot air dryers. However, maize completes its physiological maturation period at the level of 29-31% moisture. After this period it is kept in the field only to reduce the moisture level economically by sun drying. But the waiting period encourages the risk of contamination by mycotoxin producing moulds. Fumonisins are the most common mycotoxins isolated from maize and have serious effects on both human and animal health. In this study, maize harvested in five different moisture levels (29, 24, 18,5, 16 and 15%) after completing the physiological maturation period, was dried with hot air, alternatively infrared, infrared-hot air combination and microwave techniques until the moisture content comes down to %13. The effect of harvest time and drying techniques on the fumonisin contamination and the quality characteristics which are specifically important for maize crop were investigated. Consequently, only the effect of harvest time factor on fumonisin contamination found to be important statistically (p<0,01). The highest contamination dose observed at the fifth harvest period which consisted of sun dried materials. However, energy expenses of the drying techniques calculated for all harvest periods and it was found out that the expenses to reduce the moisture level from 15% to 13% with hot air drying is higher than the expenses to reduce moisture level from 29% to 13% with infrared-hot air drying combination.Key Words: Fumonisin, maize, drying, infrared.