Abstract
Transparent gels containing about 2% protein were obtained by mixing alkaline dope solution of 7 S or 11 S soybean proteins with alcohol. The 7 S component showed the ability to form a stronger gel than the 11 S. This phenomenon depended on pH and alcohol concentration. In 66% ethanol, the viscosity of the 7 S and 11 S reached maxima at pH 11.4 and 11.2, respectively. Above these pH levels where further unfolding and dissociation into subunits of the protein molecules occur, the viscosity decreased rather. The effectiveness of alcohol to increase viscosity increased in the order; n-butanol<tert-butanol<n-propanol<iso-propanol<ethanol<methanol. Alcohols having minor hydrophobicity were more effective for increasing viscosity, but ethylene glycol was ineffective. The addition of NaCl or 2-mercaptoethanol to ethanol-mixed alkaline dope solutions resulted in the remarkable increment of the viscosity, especially for the 7 S.
