Characterization of Preparation Parameters for Improved Screw Pressing of Crambe Seed

Screw pressing of niche oilseeds such as crambe may be a viable alternative to solvent extraction of oil. Cookingbefore pressing is known to improve oil recovery. Use of welldefined cooking conditions of time and temperature wasexpected to aid characterization of the relationship between cooking and press performance, and to reduce soluble seedprotein according to a fundamental kinetic model. A pressure cooker modified to permit both steam injection and vacuumpermitted the cooking of crambe seed at welldefined conditions of 90C to 120C for 5 to 20 min. Oil recovery increasedwith increasing cooking temperature and time to a maximum of 75.9% at 100C and 12 min, versus 70.9% for uncooked seed,and a low of 70.6% at 120C and 20 min. Oil recovery and press rate were nonlinear functions of cooking temperature andtime. A cooking index based on soluble protein decreased according to a modified thermal processing model with D0 and zvalues of 3.3 min and 28C, respectively. The index was also useful for identifying optimally cooked seed. Oil recoveryincreased with decreasing seed moisture content to a high of 82.5% recovery at 3.5% m.c. The approach described here maybe extended to the tuning of other screw presses for crambe and other oilseeds.