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Adhesion and Physicochemical Properties of Soy Protein Modified by Sodium Bisulfite
Author(s) -
Qi Guangyan,
Li Ningbo,
Wang Donghai,
Sun Xiuzhi Susan
Publication year - 2013
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-013-2343-8
Subject(s) - soy protein , chemistry , sodium bisulfite , food science , isoelectric point , adhesion , chromatography , adhesive , soy flour , rheology , biochemistry , organic chemistry , materials science , enzyme , composite material , layer (electronics)
Abstract Soy protein adhesives with a high solid content (28–39 %) were extracted from soy flour slurry modified with sodium bisulfite (NaHSO 3 ) at different concentrations. 11S‐dominated soy protein fractions (SP 5.4) and 7S‐dominated soy protein fractions (SP 4.5) were precipitated at pH 5.4 and pH 4.5, respectively. The objective of this work was to study the effects of NaHSO 3 on adhesion and physicochemical properties of soy protein. The adhesion performance of NaHSO 3 ‐modified SP 4.5 was better than SP 5.4; the wet strength of these two fractions was from 2.5 to 3.2 MPa compared with 1.6 MPa of control soy protein isolate. SDS‐PAGE results revealed the reducing effects of NaHSO 3 on soy protein. The isoelectric pH of soy protein decreased as NaHSO 3 increased due to the induced extra negative charges (RS‐SO 3 − ) on the protein surface. The rheological properties of soy protein adhesives were improved significantly. Unmodified samples SP 5.4 and SP 4.5 had clay‐like properties and extremely high viscosity, respectively; with 2–8 g/L NaHSO 3 modification, both SP 5.4 and SP 4.5 had a viscous cohesive phase with good flowability. Overall, NaHSO 3 ‐modified soy protein adhesives in our study have many advantages over the traditional soy protein isolate adhesive such as better adhesion performance, higher solid content but with good flowability and longer shelf life.