Oil content measurement

The total oil content measurement followed the method of Matthäus, B. and Brühl, L. (2001)

After grinding by Foss water-cooled Knifetec 1095 sample mill (Tecator AB, Höganäs, Sweden) for 10 s, about 1.0 g of powdered sample was weighted for total oil extraction by accelerated solvent extractor ASE 200 (Dionex, Idstein, Germany) with 11 mL stainless-steel extractor cell. The dead volume of the extractor cell was filled with Ottawa sand (Fisher Scientific, Rochester, NY). The following conditions were set on the ASE system: preheat for 6 min, heat for 6 min, oven temperature at 105 oC, static time for 10 min, flush volume 70%, purge time for 60s, 2 static cycles, and extraction pressure at 1000 psi. After process, extraction solvent hexane was evaporated by purging oxygen free compressed nitrogen (AGA Gas, location) above the surface. The residue hexane was removed in oven at 100 oC for about 70 min. The total oil content is calculated by the equation as follow (ref AOCS):

C = 100 x Qw / (W x (1- moisture))

in which Ow (g) is the total oil extracted from ground sample, W (g) is the weight of ground sample, and moisture% is the moisture percentage of the ground sample measured by by A & D Moisture analyzer

Oil composition analysis

1. Label the aluminum crushing trays (50 or 100 holes) with labeling tape

1. Fill each well of the tray with 5 seeds for each sample

1. Stack the trays as they are filled, always keeping the top tray covered with a glass plate

1. To crush the seed in the aluminum crushing tray using the hydraulic press, wipe the pegs of the crushing plate with a paper towel with hexane on it

1. Turn the wheel on the front of the press clockwise until it is tight. Using the lever on the right hand side of the press to crush the seed to the pressure of 40,000 lbs

1. Add 1 mL hexane to the crushed seeds in each well to cover the seeds

1. Cover the tray with a glass plate so that the hexane does not evaporate

1. Let the tray sit for a minimum of two hours

1. Load the plastic trays with vials and label them the same as crushing tray

1. Add 500 μl of 1 N sodium methoxide solution to each GC vial and transfer 100μL of hexane extraction solution from each well and place into an autosampler vial

1. Shake the vials in the plastic tray by sliding the tray back and forth on the vortex mixer for 30 min

1. After 30 minutes, add 2 mL distilled water to each vial. Let them sit still till the suspension cleans to two phases

1. Take the uplayer solution into GC vials and store at 4 oC till analysis

References

Matthäus, B. and Brühl, L. 2001. Comparison of different methods for the determination of the oil content in oilseeds. Journal of the American Oil Chemists’ Society 78: 95-102.

Authors: Juan Gao