Measuring Stevia Quality

SWEETENERS are often used in diet products. MCP polarimeters can be used to determine the quality of optically active sweeteners like stevia. The specific and optical rotation of single, purified steviol glycosides, extracted from stevia plants, can also be measured.

Stevia - sweeter than sugar, 100% organic, no calories

Stevia sweetener is prepared from the leaves of the plant Stevia rebaudiana. The stevia leaf is up to 30 times sweeter than conventional sucrose but has no calories. This makes stevia plants an ideal source for the process of low-calorie sweeteners, e.g. in diet food and diet drinks. The major components in stevia powder or liquids are called steviol glycosides. The sweetest steviol glycosides is stevioside, which can be 300 times sweeter, and rebaudioside A, which can be up to 450 times sweeter than sucrose. The exact composition of the steviol glycosides in stevia can vary and contain impurities. Therefore, the verification of the equality of the stevia powders and liquids is necessary to ensure the high quality of the product batch. Moreover, single purified steviol glycosides can be measured to validate purity and concentration.

MCP polarimeters are ideal for the quality control of sweeteners

The MCP polarimeters from Anton Paar are ideal for quality control of stevia extracts by measuring optical rotation. Further, the optical and the specific rotation of any single purified steviol glycoside can be measured. Thereby, a concentration determination of single steviol glycosides is possible. Depending on the required measurement conditions and the accuracy, MCP 100, 150, 200, 300 or 500 can be used. MCP polarimeters allow a precise analysis of stevia compounds in the milligram range due to the high resolution of up to ± 0.0001° optical rotation.

As the optical rotation is temperaturedependent, the MCP polarimeters have a built-in Peltier temperature control with an accuracy of up to ± 0.03°C. Depending on the type of instrument, a FillingCheck camera system is available which helps to verify the correct filling of the sample cell to avoid air bubbles or streaks that can lead to data falsification. Detailed information is given in the stevia application report.

Good to know

The MCP polarimeters measure the optical rotation of stevia and single, purified steviol glycosides with high accuracies. Sample cell volumes are available from 0.05 to 20ml.

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