Determination of inulin in food and beverages
Quantitative determination of inulin and relevant sugars in food and beverages, as well as identification of the botanical origin of the inulin extract
June 2026. Inulin is a high-quality plant-based dietary fibre belonging to the group of fructans. For this reason, it is increasingly used in the production of functional foods and beverages. Various analytical methods are available for determining the inulin content. Liquid chromatography coupled with a refractive index detector (LC-RI) has proven to be a highly reliable method. By coupling with an isotope ratio mass spectrometer (IRMS), the botanical origin of inulin extracts can also be determined.
What is inulin?
Inulin is a water-soluble plant-based dietary fiber from the group of fructans — also known as fructooligosaccharides (FOS) — consisting of a mixture of fructose oligosaccharides with a chain length of up to 100 monomers and a terminal glucose molecule. Inulin is used as an ingredient with probiotic effect in a wide variety of foods and beverages, and is also considered a low-calorie substitute for sugar.
Quantification of inulin and relevant sugars
The quantification of inulin and other sugars is carried out using liquid chromatography in combination with a refractive index detector. This method enables the determination of inulin as well as relevant sugars such as fructose, glucose, sucrose, and, for example, maltose, isomaltose, raffinose, and the sugar alcohol mannitol in inulin-containing foods such as inulin powders as well as inulin-containing syrups and beverages.
Sample preparation and chromatography
For analysis, the sample is simply dissolved in water and centrifuged. After injection of an aliquot of the extraction solution, separation of the analytes is performed on an ion-exchange column. Pure water is used as the eluent, and the analytes are measured by refractive index.
Determination of the botanical origin of inulin
Inulin can be obtained from a wide range of plant sources (e.g., chicory, artichoke, dahlia, and agave) by extraction with hot water, followed by purification, concentration, and drying. As the quality of the extracted inulin is influenced by the plant species, it may be important to determine the source plant. The determination is carried out analogously to the method described above, but using an isotope ratio mass spectrometer as detector. The ratio of the two carbon isotopes, ¹²C and ¹³C, is plant-specific and thus confirms the required botanical origin.
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Written by:
Jule Hansen
Eurofins Food Integrity Control Services GmbH