A New Polarimetric Method for the Analysis of Dextran and Sucrose

A new method for dextran quantification has been developed and field-trialled in Jamaica, in association with the Sugar Industry Research Institute. The method uses a near infrared (NIR) polarimeter and a specific dextranase. The dextranase selectively breaks down the dextran into sugars of lesser specific rotations without affecting any other substance present in the juice. The initial dextran concentration is derived from the calibration curve of the change in observed optical rotation (OR) due to enzymatic hydrolysis and output automatically by the polarimeter. Readings are not affected by the molecular weight of the dextrans, the entire procedure takes less than 10 minutes to perform and it is semi-automated. Use of a NIR polarimeter negates the need for lead acetate clarification. The method is suitable for both juice and raw sugar samples.