IN-STORE DRYING OF MAIZE AT SUBZERO TEMPERATURES IN NORTHEASTERN CHINA

摘要

The northeastern provinces of China make a significant contribution towards total maizernproduction of the country. In the continental climate of northeastern China, maize isrnharvested late in season and subjected to subzero temperatures shortly after harvest. It isrnshelled and kept frozen in warehouses or outdoors until spring. In-store drying usingrnambient temperatures could be an attractive option for drying of maize during the winterrnmoths but has not been tried so far. The empirical as well as theoretical modelling resultsrnshow that this process is possible. A number of thermophysical properties have beenrndetermined at subzero temperatures common in northeastern China during winter months.rnNuclear Magnetic Resonance (NMR) spectroscopy has been used to determine therndistribution of bound, frozen and unfrozen water in maize samples under subzerorntemperatures. The results of the present study indicate that -5° to -10°C is the phaserntransition temperature of water in maize at 26% wet basis. Below -10°C, the maize kernelsrnseem to contain only frozen and bound water. This finding may prove decisive in selectingrnstrategies for in-store drying at subzero temperatures.