An 22.5% SPI gel, a 22.5% starch gel, and SPI-starch complexes, that is, 15% SPI-7.5% starch gel and 7.5% SPI-15% starch gel, fabricated by partial substitution of SPI with starch were prepared for use as new ingredients in cooking. The SPI gels were hard and elastic and the SPI-starch mixture gels became softer and more fragile on decreasing the amount of SPI and increasing the amount of starch. When these gels were cooked with water and 10% sucrose solution, their hardness and cohesiveness decreased. In contrast, the SPI gels and the mixture gels prepared by heating in 1% NaCl showed no appreciable physical changes. Furthermore, the weight and physical properties of the mixture gels heated in an "umami" stock (glutamate solution), with higher NaCl concentration and lower pH value, remained constant. The 15% SPI-7.5% starch gels heated in the umami stock were found to be positive for taste. Thus, our results suggest the 15% SPI-7.5% starch gels cooked in the umami stock will have practical use in food processing and cooking in homes.