Screw pressing performance of whole and dehulled flaxseed and some physico-chemical characteristics of flaxseed oil

Screw pressing performance of whole and dehulled flaxseed at different seed moisture (6.4 to 11.1 % d.b.) and press head temperature (80-120 degrees C) was investigated. Oil recovery, residual oil, press rate and sediment content and some important physico-chemical characteristics were determined at six different levels (50, 60, 70, 80, 90 and 100 %) of dehulled flaxseed. Oil recovery decreased with increasing moisture content as well as press head temperature. Press rate was found maximum for 100 % dehulled flaxseed while minimum for 50 % dehulled flaxseed at 6.4 % moisture content. Colour of oil samples was found affected both with the level of dehulled flaxseed and press head temperature. Free fatty acids content of oil ranged from 1.07 % to 2.70 % and lower at 80 degrees C press head temperature. Oil and cake temperatures ranged from 53.10 degrees C to 65.95 degrees C and 69.15 to 103.75 degrees C, respectively. The alpha-linolenic acid content of different oil samples obtained at 80 degrees C was in the range of 53.34 +/- 0.95 to 54.21 +/- 1.04 %. In view of maximum oil recovery (82.9 % d.b.), lower FFA content, and oil and cake temperature, 7:3 ratio of dehulled and whole flaxseed having 6.4 % d.b. moisture content and 80 degrees C press head temperature may be considered for screw pressing of flaxseed.