Development of a Combined Trifluoroacetic Acid Hydrolysis and HPLC-ELSD Method to Identify and Quantify Inulin Recovered from Jerusalem artichoke Assisted by Ultrasound Extraction

Over the last years, inulin, a fructan mixture consisting of oligosaccharides and polysaccharides, has attracted more and more attention from both food industry and researchers, due to its unique functional properties as a natural resource. Therefore, there is an increased interest in the extraction and quantification of inulin for its valorization from inulin rich plants, wastes and by-products. In this work, ultrasonic treatment was applied for inulin extraction, observing a great impact of extraction temperature and ultrasonic power on the inulin content in the obtained extracts. A combined process including trifluoroacetic acid (TFA)-assisted hydrolysis and analysis with high performance liquid chromatography equipped with evaporative light scattering detector (HPLC-ELSD) was developed to quantify inulin content. The effect of hydrolysis parameters was investigated, obtaining the optimal conditions after using TFA at a concentration of 1 mg/mL, hydrolysis temperature of 90 °C, and hydrolysis duration of 60 min. The good linearity (>0.995), precision, recovery (100.27%), and stability obtained during the validation process showed that this developed method allows the quantification of total inulin content in the samples analyzed. This combined method may also contribute to the investigation of the functional properties of inulin (e.g., as prebiotic).