Dextranase in sugar industry: A review

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In sugar production, dextrans are undesirable compounds synthesized by contaminant microorganisms from sucrose, increasing the viscosity of the flow and reducing industrial recovery, bringing about significant losses. The use of the dextranase enzyme is the most efficient method for hydrolyzing the dextrans at sugar mills. Some bacterial strains, filamentous fungi and a small number of yeasts have been shown to produce dextranase. The fungal dextranases showed the highest reaction rate at low Brix, with pH and temperature close to 5.0 and 50 °C, respectively, that is, conditions existing in juice extraction. Some of these dextranases formulated in enzymatic preparations have been efficiently used for hydrolyzing dextrans in sugar mill juices. In more advanced stage of the process, where the dextrans have already caused losses, the conditions of temperature and Brix are high. However, although the volumes are smaller, the treatment with these enzymes in syrup showed the need to increase the dose, equaling dextranase consumption. Some thermo tolerant bacterial dextranases identified up to now showed a much reduced specific activity that makes their industrial use unfeasible. The fungal dextranases from Chaetomium sp. have shown the best results on dextrans treatment both in juices and syrups. Any attempt to obtain a new natural or recombinant dextranase enzyme, must be comparable with the Chaetomium enzyme.

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