Changes in Amount of Active Groups of Soybean Protein during its Gel Formation Process

Abstract

From the viewpoint of soybean protein gel utilization for human foods, studies on the conditions affecting on the chewiness or physical properties of the gels were already reported by the author. In this paper, changes of the dye binding abilities and the amount of SH group of the protein during gel formation process were investigated.
Any changes on the dye binding abilities of the protein were not observed during gel formation process of protein pastes, in both cases of acid dye and basic dye.
The amount of SH group in protein extract from undenatured soybean meal was affected by heat treatment, and after the amount of SH group reached about maximum in the range of 50-80°C, the SH group decreased rapidly. SH group in the protein paste obtained from unheated extract also decreased with the heating temperature rapidly especially in the range of 60-90°C. But in the case of the protein paste from heated extract, the amount of SH group showed low level without depending on the heating temperature, and was equal to those of the protein pastes heated above 90°C from unheated extract.
Based on the above results, the structure of the protein network was discussed in relation to gel formation of soybean protein.