The cooking and drying conditions for oilseeds preparatory to screw pressing are some of the most important factors that influence screw-press performance. Screw-press oil recovery, residual oil, pressing rate, and oil sediment content were measured for uncooked crambe seed and crambe seed cooked at 100°C for 10 min, pressed at six moisture contents ranging from 9.2 to 3.6% dry basis. Oil recovery significantly increased (P ≤ 0.01) from 69 to 80.9% and 67.7 to 78.9% for cooked and uncooked seeds, respectively, as moisture content decreased. Residual oil significantly decreased (P ≤ 0.01) from 16.3 to 11.1% and 16.9 to 11.9%, respectively, as moisture content decreased. The reduced oil loss due to only drying the seed from 9.2 to 3.6% was 32% for cooked seed, whereas cooking contributed only 3.6 to 7% reduced oil loss. Pressing rate decreased from 5.81 to 5.17 kg/h and 6.09 to 5.19 kg/h for cooked and uncooked seeds, respectively, whereas sediment content increased from 0.9 to 7.8% and 1.1 to 5.4%, respectively, as moisture content decreased. The effects of moisture content on pressing rate and sediment content were significant at P ≤ 0.05. All relationships of screw-press performance to moisture content were fitted to a second-order polynomial.

Flaxseed oil, a rich source of dietary n-3 FA, is commonly obtained by cold pressing whole seed. Furthermore, flaxseed hulls are emerging as a valuable lignan-rich product for functional food use; therefore, the pressing characteristics of dehulled seed need to be understood. Screw press performance was measured for pressing of whole and dehulled flaxseed. When whole Omega flaxseed was pressed through a 6-mm choke, an inverse relationship between seed moisture content (6.1-11.6% range) and oil recovery (70.1-85.7%) was observed. However, peak oil recovery from pressing dehulled Omega flaxseed of 72.0% was found at 10.5% moisture content in the moisture content range of 7.7-11.2%. Although oil recovery from dehulled Omega flaxseed was lower than from whole Omega flaxseed, the weight of oil produced from dehulled Omega flaxseed per unit time was higher. The dependence of capacity on moisture content was less evident with the 6-mm choke than with the 8-mm choke. An inverse relationship between moisture content of whole flaxseed and oil and meal temperature was observed. The oil and meal temperatures from pressing dehulled flaxseed were significantly lower than those from whole flaxseed. Therefore, pressing dehulled flaxseed appears to offer advantages in organic flaxseed oil production.

Crambe seed (Crambe abyssinica) is an excellent, recently established source of high-erucic acid oil. Erucic acid has a number of important and potential applications. To develop this potential, a rapid bench-scale method was desired whereby purified erucic acid in up to several 100-g quantities could be produced from crambe seed. Using the method developed, oil was expressed from dried, intact seed; clarified, degummed, and bleached; and saponified and acidified to obtain the free fatty acids. Analysis by inductively coupled plasma of the free fatty acids showed negligible levels of phosphorus and most minerals. Erucic acid was twice crystallized from 95% ethanol at −14°C, resulting in a purity of 87.1%. This process yielded 365 g erucic acid crystals per kg bleached oil. Nuclear magnetic resonance analysis showed that the prepared erucic acid had an excellent pattern of correlation with a commercial standard. The time needed to convert 1 kg of crambe seed to erucic acid is about 48 h. Crystal filtration and drying stages under the current process conditions require 30% of the overall time. The method is suitable for producing adequate quantities of erucic acid for use in studies of its bench-scale conversion. There is obviously, still, a fruitful field of work to be explored in the formalization of refining procedures for crambe oil. It seems that crambe is destined to continue expansion into the higherucic acid oil markets.Paper no. J9058 in JAOCS 76, 801-809 (July 1999).

Amaranth seed oil was fractionated in a bench‐scale short‐path distillation unit to obtain fractions rich in squalene. Fractionations were conducted with degummed amaranth oil, alkali‐refined amaranth oil, and simulated amaranth oil. Squalene concentration was increased about sevenfold with a squalene recovery of 76.0% in the distillate when degummed amaranth oil was fractionated at 180°C and 3 mtorr vacuum. Free fatty acids codistilled with squalene, lowering the squalene content of the distillate, and resulted in a semisolid distillate at room temperature. Alkali‐refining was subsequently used to reduce the free fatty acid content before fractionation. A simulated oil (7% squalene/93% soybean oil) and alkali‐refined amaranth oil were fractionated at three temperatures (160, 170, and 180°C) and five vacuum settings (10, 100, 200, 400, and 600 mtorr). The highest squalene recoveries from simulated oil and alkali‐refined amaranth oil were 73.4 and 67.8%, respectively, both at 180°C and 100 mtorr, which translates to 12.1‐and 9.2‐fold increases in squalene concentration, respectively. The squalene recovery of the alkali‐refined amaranth oil at 180°C was not significantly different at 10 mtorr vs. 100 mtorr. The results of this study can be used as a component to assess the economic feasibility of fractionating amaranth seed for starch, oil, meal, and squalene.

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