Corn oil typically is recovered from the corn germ through a solvent-based process using hexane. Due to capital equipment requirements and special handling and disposal considerations, the use of hexane is considered a rather expensive process. Unfortunately, water-based methods for oil recovery have not been successful because the yields of corn oil are much less than those obtained using hexane extraction.
A thermal analysis of the unprocessed germ was performed to identify whether ambient or cryogenic grinding would be recommended. The transition temperatures were measured on a differential scanning calorimeter (DSC). The DSC output shown in figure 1 identified a glass transition temperature (TG) for the starch component at around -72°F (-58°C) and a melting temperature (TM) for the oil component at around -4°F (-20°C). These results were consistent with literature values for similar materials. Therefore, based on the rather low TG, the material was considered appropriate for using cryogenic conditions in grinding to expose sufficient surface area to maximize the oil extractability.