3.5. Comparison of solvent extracts
The relative amounts of phenolics in pulses differed significantly
(Pb0.0001) among types, millstreams and extracting solvents
(Tables 1–4). Maximum differences were observed in total phenolics
of the lentil and yellow peas only when extracted with aqueous
acetone comparable to those reported earlier (Xu & Chang, 2008),
with two different aqueous acetone concentrations. Aqueous acetone
extracted over twice (2.2–2.5×) the antioxidant level than hot water
or aqueous ethanol from whole lentils, but less than half (0.4–0.5×)
the amount from yellow peas. The lentil hull presented the best source
(material) for antioxidant recovery, since the acetone extract
exhibited almost three times (2.9–3×) the antioxidant activity of
the ethanol extract. Ethanol, known as an effective solvent for the
recovery of phenolic compounds, was the best antioxidant extractant
for yellow peas, similar to aqueous acetone and, 1.4–2× more efficient
than water extract. Aqueous ethanol extracted the least amount
(about 3 times less than extracted with acetone) of total phenolic. The
highest amount of total phenolic was extracted with hot water and
water from whole seed and residue and with acetone from the hull.
However, these high phenolic water extracts exhibited weak
antioxidant activity relative to acetone extracts. Hot water and
water actually extracted more total phenolics than aqueous acetone
or ethanol from the whole, hull and residue of yellow pea. This is in
contrast to the superior polyphenol extraction of pea seed coat with
acetone–water system compared with ethanol–water system
reported by Troszyńska et al. (2002).