PRODUCING HIGH-PURITY INULIN POWDER FROM CHICORY ROOTS

Abstract

The suitability of an inulin powder to be used in pharmaceutical applications is primarily based on its purity; however, inulin extracted from the conventional extraction trains is frequently contaminated with free sugars, proteins and pigments. A systematic process for the development and optimisation of an integrated process for the production of high-purity inulin from chicory (Cichorium intybus L.) roots based on hot-water extraction, membrane purification and spray drying is developed. The Box–Behnken design was implemented to optimise hot-water extraction and evaluated by three factors: namely, temperature, solid-to-liquid ratio and extraction time.  The fitted quadratic model was significant (p < 0.001) with R² = 0.972 and a non-significant lack-of-fit (p = 0.18); the predicted optimum (80 °C, 1:15 g mL⁻¹, 60 min) gave an inulin recovery of 84.2 ± 1.5%, agreeing with the model prediction within 3%. The clarified extract was refined by microfiltration followed by nanofiltration with diafiltration, raising inulin purity from 71.3 ± 2.4% to 93.6 ± 1.3% of dry solids, although a measurable decline in permeate flux indicated membrane fouling. The nanofiltration concentrate (about 7 to 15 °Brix) was demineralised on a two-bed anion- and cation-exchange resin column to remove residual inorganic impurities and then concentrated by multiple-effect evaporation (about 15 to 35 °Brix) ahead of drying. Spray drying of the retentate, optimised for inlet air temperature and feed concentration, produced a low-moisture powder (4.6 ± 0.3%) at a yield of about 69%, with the main losses associated with wall deposition. The results indicate that an integrated, purification-focused workflow can deliver high-purity inulin from an inexpensive feedstock, and they provide a basis for future scale-up and pharmacopoeial qualification studies.