Systematic study on the enzymatic decomposition of various dextran fractions. (May 2019) - Abraham, K.
Graphical abstract: Highlights: This work aims at controlled dextranase application during sugar manufacture. Analysis of enzymatic reaction products by size exclusion and affinity chromatography. Average molecular masses and percentage shares of the reaction products were determined. Details of gradual reduction of the molecular mass with the increase of enzyme level and reaction time were identified. Degradation process reveals surprising variation based on dextrans' initial molecular mass distribution. Abstract: Investigations on the enzymatic decomposition of dextran with varying initial average molecular masses, aiming at controlled dextran-related process effect mitigation during sugar manufacture, were key to this study. HPLC with size exclusion columns revealed that the enzymatic decomposition follows a gradual pattern leading to a successive reduction of the average molecular mass with the increase of the enzyme level and the incubation time. Affinity chromatography additionally revealed that oligo-, tri- and disaccharides constituted the smallest possible units. The amount of these small-sized saccharides increased with higher enzyme level and extended incubation time. Both effects were found to be further progressed when decomposing T40 as well as an equal-mass mixture of T2000 and T40 compared to exclusively T2000. The decomposition using unusually high enzyme levels leads to very similar reaction products for all substrates investigated. Besides, it was found that the presence of 15% (m/m) sucrose seems to hardly affect the enzyme reaction so that the enzyme application in raw sugar juices seems to be appropriate. The work presented suggests that not only the dextran content, but also the average molecular mass and the polydispersity of dextran are decisive for targeted dextranase applications in sugar industry practice.