Enzymatic long-term stability

To fulfill the needs for long term stability of a biological material, the optimum range of water activity lies between 0.20 and 0.35, This area represents the best compromise between lipid oxidation and non-enzymatic browning. Enzymatic browning is suppressed under these conditions, and growth of microorganisms is impossible. 

Long-term stability without loss of immimological and enzymatic activities. 

Ferloni, C., Heinemarm, M., Hummel, W Daussmarm, T, and Biichs, J. (2004) Optimization of enzymatic gas-phase reactions by increasing the long-term stability of the catalyst. Biotechnol. Prog.,... 

Due to their limited stability, the use of immobilized enzymes might be problematic for monitoring enzyme production (e. g., urease for arginase monitoring). Optical methods which do not need immobilized biocompounds should be more profitable in long-term procedures. Nevertheless, special dyes or substrates with varying optical characteristics after an enzymatic conversion must have at one s disposal. 

Physical entrapment is now rarely used because the presence of the enzyme in solution does not give good long-term enzymatic activity. Chemical immobilization, using covalent bonds, ensures a greater long-term enzymatic stability [24], and a number of examples of this will now be described. 

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