Mechanical Oil Expression from Extruded Soybean Samples

Soybean is generally recognized as a source of edible and industrial oil, and the deoiled meal is seen as a source of protein in animal feed. In recent years, however, more interest has been directed toward using soy meal as a protein source for human consumption. Extrusion-expelling of soybean provides an opportunity in this direction. The main focus of this study was to maximize the oil recovery from extruded soybean processed using three different kinds of extruders and processing conditions. These extruded samples were later pressed uniaxially in a specifically designed test-cell and the oil recovery was recorded over time. The effects of process variables, including applied pressure, pressing temperature and sample height, were investigated. Results indicated that over 90% of the available oil could be recovered from pressing of extruded soy samples. The information generated is likely to be useful in interpreting the effect of process variables and extruding equipment for pretreatment of soybean for subsequent mechanical oil expression.