The sample (1 g) was accurately weighed into a 200-mL Pyrex beaker, treated with ca. 100 mL of boiling water at pH 6−8, and kept at 85 °C with continuous magnetic stirring on a hot plate for 15 min. It was then cooled to room temperature, the volume was made up to 100 mL, and the solution was filtered through a 0.20-μm membrane filter (Minisart Sartorius or equivalent) before injection. If the filtrate is kept refrigerated before analysis, the fructan tends to precipitate from solution, so it should be reheated to 80 °C and allowed to cool to room temperature before analysis.
The chromatographic equipment consisted of a Waters 6000A pump system, a Waters injector with a 50-μL sample loop, a refractive index detector (Waters R40), and an integrator (Data Module Waters). HPLC conditions were an Aminex HPX-87C (Bio-Rad) anion-exchange column, with deionized water at 85 °C as the mobile phase at a flux rate of 0.6 mL/min.
Calibration curves were plotted with 0.005−1 g/100 mL of inulin. To identify other sugars commonly present in samples, reference solutions with 1 g/100 mL of mono- and disaccharides were tested.
All determinations were made in triplicate.