Ben-Efraim, A., Department of Stored Products, Institute for Technology and Storage of Agricultural Products, Agricultural Research Organization, Bet Dagan, 50250, Israel
Lisker, N., Department of Stored Products, Institute for Technology and Storage of Agricultural Products, Agricultural Research Organization, Bet Dagan, 50250, Israel
Henis, Y., Department of Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, 76100, Israel

Spontaneous heating occurred in stored soybeans in Israel after only a few months of storage. In bins where spontaneous heating (to about 40°C) was detected early, soybean moisture content (m.c.) started to increase from the original 12-13% to 13.3-13.9% at the 2 m depth level and the free fatty acids (FFA) level, mould counts, and respiration remained at levels acceptable for commercially stored soybeans. Aeration of the bins caused a decrease in temperature at the 2 m depth level and equalised the temperature of the whole bulk. In one case, where initial heating was not detected early enough, a 30-50 tonne core of a total of 2000 tonnes burned, the core being located in the upper portion of the bulk. At the core of the heat-damaged soybeans, FFA level increased to more than 35%, while at the outer edge of the core FFA content was 22-24%. Because of the high temperature developed (up to 98°C), no fungi could be isolated from the heat-damaged soybeans. A great amount of dockage and split soybean seeds was found in the heat-damaged core. Intact soybeans around the heat-damaged bulk were not affected. In small soybean conglomerates found in the bin during the unloading process, the FFA content had increased to about 12% and mould count to about 106 propagules/g. Aspergillus flavus was the only fungus isolated in all samples examined from this silo. In silos where aeration and refrigeration operations were performed periodically, seed temperature was kept low, permitting prolonged storage of soybeans. After almost 4 years storage, the FFA content of the soybeans was about 1% and fungal counts did not exceed 102 propagules/g. © 1985.