The determination of moisture content by differential weighing before and after drying is suitable for nearly all foods. The weight loss of heat sensitive sugars may be affected two fold during drying: Volatile decomposition products add to the weight loss, whereas the crust typically formed during heating of sugar may prevent complete moisture evaporation. A study at the University of Hohenheim has shown that weight loss of sugar and fructose syrups as measured with METTLER TOLEDO’s HR83 Halogen Moisture Analyzer corresponds to the water content chemically determined by Karl Fischer titration. Three drying programs (gentle, standard and rapid) on the HR83 were tested at different temperatures with varying sample sizes. All three methods demonstrated a good correlation to the reference value determined with KF Titration.
Optimizing Drying Procedures
In tests with inverted sugar and fructose syrups, the German researchers found that the rapid drying program was not only the fastest but also the least sensitive against temperature and sample weight. The use of glass fiber pads optimized the drying procedures as they increased the surface area of the syrups and ensured complete and reproducible evaporation. Accuracy and repeatability were satisfying for most instrument settings tested as estimated by the relative standard deviations of the measurements. In general, the data shows that the HR83 heats the samples quickly and homogenously and provides accurate and reproducible results for sugar and fructose syrups.
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METTLER TOLEDO specializes in the area of precision instruments for professional use. METTLER TOLEDO laboratory instruments are used in research, scientific, drug discovery, and quality control labs, amongst many others in the pharmaceutical, chemical, food and cosmetics industries.