Gelation Characteristics and Turbidities of Sesame Protein and Soybean Proteins

Abstract

The gelation characteristics of the mixtures of sesame Extract II, consisting mainly 13 S globulin, and one of the following soybean proteins, namely, cold insoluble fraction (CIF), 7 S globulin and 11 S globulin, were investigated. At pH 7.0 and in NaCl concentration of 2%, homogeneous gels were obtained in the mixtured solutions ranging in soybean protein percentages over 40%. Under the same conditions sesame protein formed gel but heterogeneous one, which could be ascribable to a poor interaction of the protein to the solvent at this pH. At pH 10.0 and in NaCl concentration of 5%, sesame Extract II formed homogeneous gel in the protein concentration of 2%. At both the pHs, characteristic change of critical gelling concentration was observed with changing the mixing ratio. Turbidity measurements were carried out at pH 7.0 and 10.0 with changing NaCI concentration from 0.1M to 2.0M. The results were compared and discussed in the relation to critical gelling concentration of respective proteins. The temperature in which the first rise of turbidity occured and the magnitude of the gain in turbidity at that temperature could be taken as a measure of easiness of gelation.