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Functional properties of the acidic and basic subunits of the glycinin (11S) soy protein fraction
Author(s) -
Dias Kalyani,
Myers Deland J.,
Bian Yilin,
Lihono Makuba A.,
Wu Shaowen,
Murphy Patricia A.
Publication year - 2003
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/s11746-003-0736-7
Subject(s) - solubility , isoelectric point , chemistry , protein subunit , chromatography , soy protein , biochemistry , organic chemistry , enzyme , gene
The functional properties of low‐ and high‐M.W. (LMW and HMW, respectively) acidic subunits and the basic subunit separated from the 11S soy protein fraction were studied and compared with the functional properties of the 11S fraction. Among the functional properties investigated were solubility, emulsification, and viscosity. The results showed that the LMW acidic subunit had higher solubility than the HMW acidic subunit. Among all the samples, the LMW subunit separated by using β‐mercaptoethanol (ME) was the most soluble, with a solubility of 98–100% at a pH of 6–12. The solubility profile of the HMW subunit followed a pattern similar to the solubility of 11S. The lowest solubility was observed around pH values in the range close to the isoelectric point for both the LMW and HMW subunit. The basic subunit was not soluble in the pH range 3–10; however, the solubility increased more than 50% at pH 13 compared to the solubility at pH 10. The emulsification capacity of all subunits was higher than 11S in the following descending order: LMW, basic, HMW, 11S. Emulsification activity and stability of the subunits were greater than those of the 11S samples at room temperature and 95°C. With the exception of the LMW subunit separated with ME, the subunits had a higher viscosity than 11S. The basic subunit separated with sodium bisulfite had the highest viscosity of all the samples tested.