Question

4) Discuss in detail an appropriate method for determining the moisture content of sugar

Answer 1

The ICUMSA International commission for uniform methods of sugar analysis, an oven method , was used to determine the moisture in the sugars. The oven value will be the standard for deciding on the parameters for programming the instruments.

Loss on drying requires 3 hours of oven drying followed by an extended cooling period to a temperature 2°C above ambient. Recently instrumentation has become available that is capable of measuring the small amount of moisture content in white sugar.

The Arizona Instruments computrac MAX-2000 moisture analyser uses small convection air oven to effect drying. The instrument corporation mark 1 high performance moisture analyser utilizes for quartz infrared heaters.The choice of optimal drying parameters plays a critical role in successful moisture examination in white , raw , powdered and soft brown sugars.

A number of variables are decided when programming these instruments to obtain
optimum performance. Drying parameters include temperature, time, sample size, stand-by
temperature, one or two-stage drying and choice of end of analysis mode. Although one oven method can accommodate the range of moisture in sugar products, from 0.01 % in white sugar up to 3.5+% in soft sugars, there is a choice of programmable drying options for instrumental methods, and the choice of parameters is dependent to some degree on the type of sample, its moisture content and particle size. Instrumental moisture tests can be ended on time or on determination of a constant rate of weight loss. End of analysis based on slope/rate is based on determining a percent of initial weight change over a chosen period of time. The test ends when slope conditions are met. The amount of slope/rate chosen depends on the amount of moisture in the sample. The analyser has the choice of ending the test on the actual slope, when the slope conditions are met, or on a calculated or predicted slope. In this mode, the test is ended before the actual end point will be reached, based on prediction algorithms.
Advantages of this mode are a shortened analysis time, allows use of a higher starting temperature, and avoids sample decomposition. Prediction mode is best used for high moisture products.