Effects of Ca²⁺, Mg²⁺ on Gel Formation of the Mixture of Myosin B with Soybean Protein CIF

Interaction of Muscle Protein and Soybean Protein (Part 7)

Abstract

Under five optimum conditions for gel formation, the effects of added Ca²⁺ or Mg²⁺ on the heat-induced gelformability were examined using a mixture of myosin B with soybean protein CIF (Cold Insoluble Fraction). The following results were obtained. 1) Rheologically, irregular networks were formed in the presence of Ca²⁺ or Mg²⁺ below 100°C which resulted in the formation of a short gel. Generally, the toughness and firmness of the gel increased with the increase of Ca²⁺ concentration, but Mg²⁺ was not as effective as Ca²⁺. 2) By a high-temperature treatment (135°C), the gel became firmer, tougher and shorter in the presence of Ca²⁺. When the gel was subjected to three-step heating, the properties of the gel were different from that subjected to the single-step heating, which was also observed in the gel formation with Mg²⁺ added. 3) When EDTA was added to the protein solution, the gel formation at 100°C or below was different from that at 135°C,i. e., gel formation was accelerated at 100°C and below by the addition of EDTA to the system, while at 135°C, it was suppressed. It was suggested from these results that a Ca²⁺ or Mg²⁺-linkage contributed to the gel formation at a high temperature (135°C), but induced the formation of irregular networks of the gel at 100°C or below.