Compression testing of non-roasted bulk oil palm kernels at different processing factors was performed using a universal compression testing machine and a pressing vessel witha plunger. The purpose of the research was to describe regression models of deformation, deformation energy and percentage kernel oil depending on force, speed and vessel diameter. The tested compression forces were 100, 125, 150, 175 and 200 kN, while the speeds were 5, 10, 15, 20 and 25 mm min−1. Three pressing vessels of diameter 60, 80 and 100 mm were used. Samples were compressed at an initial height of 60 mm. For varying forces and vessel diameters at a constant speed of 5 mm min−1, the values of deformation, deformation energy and percentage kernel oil ranged from 28.47±0.89 to 37.45±0.11 mm, 796±0.82 to 1795±49.01 J and 7.33±0.26 to 25.67±0.39%. At a constant force of 200 kN for different speeds and vessel diameters; the aforementioned determined parameters also ranged from 31.91±1.61 to 37.63±1.21 mm, 1012±26.76 to 1795±49.01 J and 14.66±0.42 to 24.98±1.37%. The results were statistically significant (p<0.05) or (F-ratio>F-critical), with high coefficients of determination between 0.74 and 0.99. Thus, higher force at specific speed may be needed to maximally recover kernel oil.
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