Screw pressing characteristics of dehulled crambe seed
2004
Singh, K.K. | Wiesenborn, D. | Kangas, N. | Tostenson, K.
Screw press performance with a given oilseed depends on the method of preparation before pressing. Oil recovery and press rate of two screw configurations, R-8 and R-11, that differed in flight pitch, height, and width, were compared at dehulling levels from 0% to 100%. The oil recovery with the R-11 screw was better than that of the R-8 at dehulling levels greater than or equal to 40%, and the press rate was similar. Thus, the R-11 was selected for a subsequent experiment involving four preparation parameters (dehulling level, cooking time, cooking temperature, and moisture content), each at five levels, using a central composite rotatable design. Multiple regression analysis of the experimental results revealed that linear, quadratic, and interaction terms of the parameters cooking time, cooking temperature, and dehulling level were non-significant even at P > 0.10; however, the linear term for moisture content was significant at P less than or equal to 0.001. A comparison of oil recovery for cooked seed/kernel versus uncooked at different dehulling levels (30% to 70%) indicated a significant difference at P less than or equal to 0.01, but the improvement in oil recovery due to cooking was small. A steady rise in oil recovery with decrease in moisture content from 9% to 3% was observed. Moisture content was the major factor influencing press rate, followed by dehulling level and cooking temperature, respectively. It was concluded that acceptable screw press performance was achieved with dehulled crambe seed, that proper moisture content adjustment before pressing dehulled seed was important, and that cooking dehulled seed was of negligible benefit.
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