IMPACT OF THE MAIZE HYBRIDS FAO GROUP ON THE WATER RELEASE RATE BY DRYING AND GRAIN NUTRITIONAL VALUE

The most important energy feed in the Republic of Croatia is maize grain, and as a consequence of a large number of hybrids, the largest variations in the chemical composition are present. Maize grain must be preserved from one harvest to another. At harvest time, it has higher moisture content than the equilibrium and, in order to be stored, must be conserved. One way of conservation is convection drying. Since different grain hybrids with different initial humidity, morphological structure and the size of the grain are dried simultaneously in the drying process, different grain behavior occurs in the drying process. The release of surplus water to the equilibrium humidity (14%) is different for each hybrid, therefore the aim of the paper is to determine the water release rate through exponential equations for 4 different FAO maize groups 300, 400, 500 and 600. Also, the grain fracture after drying, which represents the simulation of the grain fall in the silage cell, as well as nutritional value of investigated maize hybrids after the drying process and after a year of storage under the cooled conditions (5 degrees C) will be determined. The slowest trend of drying had the FAO group 500 hybrid, while the fastest had the FAO group 400 hybrid. The drying speed affected the grain fracture, and the slowest-dried FAO group 500 hybrid achieved the lowest percentage of fracture (24.0%), while the fastest-dried FAO group 400 hybrid achieved the highest percentage of fracture (48.4%). Hybrids had similar nutritional values, and they did not change significantly during the storage period, what makes convection drying and cooled storage a good method of maize grain storage.