Comparison of methods for dextran analysis: Effect of sugar and dextran concentrations

The presence of dextran in the process streams of a sugar factory is an immediate indicator of sugar loss. In the present study, four methods used for dextran determination in sugar factory process streams were assessed -the Haze method, the Modified Haze I method, the Modified Haze II method, and enzyme-linked immunosorbent or ELISA method. All four methods were both accurate and reproducible in the range 10-100 ug/ml dextran in pure dextran solutions. Only the Modified Haze I and II methods gave acceptable results in the range 100-1000 ug/ml dextran in dextran solutions and in dextran solutions containing 15 % sucrose. The two methods were also able to give accepted results with factory samples diluted to 15 Brix. However, the factory samples should be diluted to dextran concentrations between 100 and 5000 ug/ml dextran prior to analysis. As this study established that sucrose interferes with haze formation, the Modified Haze II method is the preferred method for routine dextran analysis in a sugar factory. However, further studies of the Modified Haze II method are suggested.