Study of the Impact of Different Types of Hydrocolloids on the Enzyme Stability and Activity during Freeze-Drying of Chymosin

M. DONEVA, Ts. TSVETKOV, L. GEORGIEVA, I. NACHEVA and N. POPOV
Institute of Cryobiology and Food Technologies, BG-1407 Sofia, Bulgaria

Abstract

DONEVA, M., Ts. TSVETKOV, L. GEORGIEVA, I. NACHEVA and N. POPOV, 2005. Study of the impact of different types of hydrocolloids on the enzyme stability and activity during freeze-drying of chymosin. Bulg. J. Agric. Sci., 11: 521-529

Here we present the results of the study for finding the cryoprotective and stabilization effect of some types oligo- and polysaccharides of different origin (agar, sodium alginate, caragenan, pectin, Na - carboxymethylcellulose, potato starch, guar and xanthane gums) during freeze-drying of the chymosin enzyme. Lyophilization is performed at different regimes of freezing - conventional, quick, shock (- 196°C).
Studies proved that after a preliminary preparation of the enzyme solutions by their embedding in polysaccharide matrixes to stabilize the protein molecules and determine the optimal regime of freezing, the sublimation drying is an effective method for production of dry chymosin preparations with low content of residual moisture. The used oligo- and polysaccharide supports provided for the formation of hydrogen bonds necessary for maintaining the native protein structure, and with their chemical composition and technical - functional properties had a good cryo protective effect on enzyme molecules.

Key words: freeze-drying, chimosin, enzyme activity, oligo-, polysaccharides