Sem. Ortiz et Mc. Anon, Analysis of products, mechanisms of reaction, and some functional properties of soy protein hydrolysates, J AM OIL CH, 77(12), 2000, pp. 1293-1301
Soybean protein isolates were hydrolyzed with papain, bromelain, cucurbita,
hieronymin, and pomiferin. The highest hydrolysis rate for cucurbita and t
he lowest for papain was detected at 720 min. Gel filtration, reversed-phas
e liquid chromatography, and electrophoresis showed that the action of each
protease was different. Pomiferin acted on the native structure of beta -c
onglycinin and glycinin, generating a large number of small hydrolysis prod
ucts with hydrophilic and hydrophobic characteristics. The hydrolysates obt
ained with cucurbita showed residual structures that were almost intact and
very similar to the substrate and contained a low number of small peptides
. The hydrolyzates obtained with papain, bromelain, and hieronymin had hydr
olysis products with structures similar to the partially hydrolyzed native
isolate. The molecular masses of these products were similar to or lower th
an the controls. Polypeptides of low molecular mass were also detected. The
prevalence of one-by-one and zipper mechanisms was suggested for cucurbita
and pomiferin, respectively. For the other proteases both mechanisms were
likely to coexist. The solubility of hydrolysates and their ability to form
and stabilize foams correlated well with the structural properties and wit
h the suggested mechanisms of hydrolysis. The best properties were presente
d by the hydrolysates prepared with cucurbita. Foaming ability for pomiferi
n hydrolysates was as high as that for unhydrolyzed soy isolate, but the fo
ams were extremely unstable.