κ-Carrageenan has been widely used as an immobilization matrix for cells and its successful applications depends on how much the cell viability maintains through the gel preparation process. High temperature is required to mix cells with κ-carrageenan gel solution and such high freezing temperature of pre-gelled solution of κ-carrageenan may decrease cell viability. Decreasing solidifying point of the gel is one of the methods to solve this problem. Gelatin, sodium carboxymethylcellulose and agar were added into κ-carrageenan solution; therefore a mixed gel with lower solidifying point was formed. The freezing temperature of mixed κ-carrageenan entrapment decreased about 10°C, while the mixed gel had as high strength as the single gel formed only from κ-carrageenan. Moreover, the activity of fumarase of the cells, immobilized by the mixed gel, increased from 78.5% to 89.5%, compared to that entrapped by the single gel. The mixed gel also had longer operation period.

Key words κ-carrageenan, mixed gel, enzyme activity