Secondary extraction of soybeans using hexane-acetic acid: Effect on beany flavour removal and physico-chemical properties.

Sensory and physicochemical characteristics of soy meal obtained after secondary extraction of soy
flakes using hexane containing 3 or 5% acetic acid were compared with those of hexane-extracted meal.
Sensory evaluation study using the threshold dilution technique showed a 55-63 % reduction of beany
flavor in treated meals. Hexane containing 5% acetic acid treatment showed total inactivation of
lipoxygenase (L-1 and L-2 + L-3), but no effect on trypsin inhibitor activity. Compared to hexaneextracted
meal, the nitrogen solubility index of hexane containing 3 and 5% acetic acid extracted meal
showed reductions of 19 and 39%, respectively. In vitrodigestibility increased in treated sample (81.7 %)
as compared to that of hexane-extracted meal (76.7% ). Gel filtration, polyacrylamide gel electrophoresis,
and fluorescence emission spectrum indicated the dissociation of proteins into lower molecular
weight protein fractions in treated meals; the higher the concentration of acetic acid in hexane,
the greater was the extent of dissociation.