EFFECT OF PRETREATMENTS ON PERFORMANCE OF SCREW PRESSING FOR FLAXSEED

The influence of different pretreatment conditions and moisture content of flaxseed prior to pressing was studied on the screw press performance. Oil recovery, residual oil in cake, press rate and sediment content were measured as a function of pretreatments and moisture content for screw pressing of flaxseed. The pretreatments had significant effect on residual oil and press rate but nonsignificant effect on oil recovery and sediment content. An inverse relationship between seed moisture content and oil recovery was observed in pressing flaxseed that means decreased moisture content in the range of 13.8 to 6.5% resulted increased oil recovery from 44.4 to 73.3%, 36.4 to 76.6% and 45.4 to 81% for the only moisture conditioned, steam- and enzyme-treated seeds, respectively. The residual oil decreased significantly with decrease in moisture content from 13.8 to 6.5% while the press rate and sediment content were not affected significantly with decreased moisture content. Therefore, pressing of flaxseed at lower moisture content appears to offer more benefits rather than other pretreatments, steam and enzyme treatments attempted in this study. PRACTICAL APPLICATIONS The screw presses are used for the small scale processing of flaxseed. The performance of the screw presses could be improved by selection of appropriate pretreatments prior to screw pressing. Hence, the information generated in this study would directly benefit the processors in selection of pretreatment conditions for better screw press performance. It would also be useful for the researchers to have better understanding of screw pressing under different pretreatment conditions.