RELATIONSHIP BETWEEN THE METHOD OF OBTENTION AND THE STRUCTURAL AND FUNCTIONAL-PROPERTIES OF SOY PROTEIN ISOLATES .1. STRUCTURAL AND HYDRATION PROPERTIES
S. Petruccelli et Mc. Anon, RELATIONSHIP BETWEEN THE METHOD OF OBTENTION AND THE STRUCTURAL AND FUNCTIONAL-PROPERTIES OF SOY PROTEIN ISOLATES .1. STRUCTURAL AND HYDRATION PROPERTIES, Journal of agricultural and food chemistry, 42(10), 1994, pp. 2161-2169
Soy protein isolates exhibit heterogeneous protein subunit composition
s; their structural and functional properties are determined by the pr
ocessing conditions. Drastic thermal conditions at pH 7 and 9 result i
n protein denaturation and polymerization, as evidenced by increased w
ater retention capacity and lower solubility, surface hydrophobicity,
and a higher level of AB-11S aggregates. Treatments of glycinin with u
rea and Na2SO3 at pH 7 incorporated 20% of sulfonate groups, resulted
in no solubility losses of 11S protein A and B polypeptides, but incre
ased their surface hydrophobicity. The increase of 7S fraction leads t
o an increase of aliphatic hydrophobicity. Thermal treatments at pH 7
and lower protein content lead to high solubility and high surface hyd
rophobicity isolates. 7S globulin was completely denatured, while 11S
denaturation depended on the treatment conditions; different proportio
ns of AB-11S, beta-7S, and B-11S aggregates were formed. Thermal treat
ments at pH 9 favored dissociation and denaturation of AB-11S protein.