2.2. Extraction and fractionation of FL
The extraction and fractionation methods used were those described
by Panozzo, O’brien, MacRitchie, and Bekes (1990) with
some modifications. Wheat flour (100 g, 14% moisture basis) was
extracted for 22 h with light petroleum ether (boiling range 30–
60 C) using a Soxhlet apparatus. Solvent was removed from the
extracted FL by a rotary evaporator under reduced pressure at
35 C until a little remained, and then the concentrate was transferred
to a tared vial. The final traces of solvent were evaporated
by gently blowing nitrogen gas over the lipid extract, the amount
of FL weighed, then dissolved in a fixed volume of solvent and
stored in a flask in which air had been displaced with nitrogen at
4 C. The defatted flour was air-dried at room temperature until
the solvent odors were no longer detected and was then sifted
through a 80-mesh sieve (200 lm openings).
About 2 g of FL were fractionated by column chromatography
(21 400 mm) on silicic gel (50 g) into NL and PL by sequential
elution with 300 mL chloroform and 300 mL methanol, respectively.
The elution rate was 2.5 mL/min. The complete elution
was ascertained by spot tests on thin-layer plate coated with silicic
gel G. The solvent in the two fractions (NL and PL solutions) was
evaporated on a rotary evaporator until a little remained, respectively.
Then, the respective concentrates were transferred to a
tared vial. The final traces of solvent were evaporated by gently
blowing nitrogen gas over the concentrates. The respective
amounts of NL and PL were weighed. The total recovery of NL
and PL averaged >95 g/100 g FL and mean yield of NL was 56.8 g/
100 g FL. NL and PL were stored for use as FL.
2.