Microstructure of Soybean Protein Aggregates and Its Relation to the Physical and Textural Properties of the Curd

The microstructure of soybean protein aggregates was examined by the optical microscope and the scanning electron microscope. The effects of heat and coagulating agents on the microstructure of the aggregates and on the physical and textural properties of the protein curd were investigated. Isoelectric point precipitation and calcium coagulation did not change the globular structure of the native soybean protein. However, heating induced the destruction of the native protein body. Heat denaturation of the protein was necessary in forming the network structure of the aggregates. When the protein aggregates were frozen, their structure became better defined and enlarged. The three dimensional network structure of the aggregate derived from heated soybean protein showed a low sedimentation rate, high curd yield, high water‐holding capacity, low value of hardness and high springiness compared to the unheated precipitates of globular structure.