Dextranase application in sucrose solutions -towards a better understanding

摘要

This work is concerned with the decomposition of dextran by dextranase action (Sugazym DX L, StemEnzym). Detailed analysis of dextran and potential decomposition products is key to this work. Different analytical methods (Haze, Roberts' Cooper methods, chromatography) were used and new insights into the enzymatic degradation of dextrans could be derived from their combination. The Haze method rather non-specifically detects larger branched dextrans. This is practical because the larger branched dextrans are known to predominantly cause processing problems. However, what degradation products appear and how they influence the manufacturing processes is not understood in great detail. The work performed hence actually tries to elucidate this subject matter. Combination of industrially relevant enzyme and dextran levels yielded decomposition products in the range of 40 kDa to trisaccharides. At higher enzyme levels decomposition to smaller saccharides appeared. The crystallization experiments performed indicated that the presence of dextran has a significant influence (crystallization, particle size distribution, crystal morphology). It is found that dextran led to a wider particle size distribution. Light microscopy images illustrate morphological changes induced by the presence of dextran (distinctly elongated, slightly elongated and agglomerated crystals). The precise effect of different dextran fractions on the crystallization is still not fully mapped and certainly needs further investigation. Nevertheless, a negative effect on the crystallization and the crystal characteristics could be detected, while an enzyme treatment reduces or rather eliminates these negative effects taken appropriate enzyme dosages and exposure times are used.