Sj. Ge et Lx. Zhang, PREDIGESTION OF SOYBEAN PROTEINS WITH IMMOBILIZED TRYPSIN FOR INFANT FORMULA, Applied biochemistry and biotechnology, 43(3), 1993, pp. 199-209
Soybean protein isolates of low soybean trypsin inhibitor (STI) residu
e were prepared by acidic precipitation of soybean flour water extract
s (0.8-1.2%) at pH 5.0, followed by acidic washing at this PH and affi
nity adsorption of residual STI with immobilized trypsin on polystyren
e anion-exchange resin GM 201. After heat treatment, soybean protein i
solates were subjected to controlled hydrolysis with the immobilized t
rypsin. Then, the predigested soybean protein was prepared. The predig
ested soybean protein was free of STI activity, and its solubility at
acidic pH range was greatly increased. Sedimentation test showed that
it formed a much finer clot at PH 4.5 than that of untreated soybean p
rotein. The pepsin digestibility index at pH 4.0 and chymotrypsin dige
stibility index at pH 8.0 were obviously improved. These results sugge
sted that the predigested soybean protein prepared by this method may
be used in infant formulas.