Studies on the extracting technical conditions of inulin from Jerusalem artichoke tubers

Inulin is widely used in functional foods throughout the world for its health-promoting and technological properties. Jerusalem artichoke is cultivated widely in the northern part of China for environment protection. Jerusalem artichoke tubers with 14–19% inulin can be a valuable source of inulin. To optimize conventional extraction of inulin, various combinations of pH, time, temperature, and solvent:solid ratio were used. Experiment design employed fractional factorial design (FFD), path of steepest ascent, central composite design (CCD) and response surface methodology (RSM). The empirical model developed by RSM was adequate to describe the relationships between the studied factors and the response of inulin extraction yield. Based on canonical analysis, the optimal conditions for maximizing inulin extraction yield (83.6%) were at natural pH for 20 min at 76.65 °C and solvent:solid ratios of 10.56:1 (v/w). Moreover, comparison of conventional extraction, direct sonication extraction, indirect sonication extraction showed the indirect sonication extraction is a suitable method for inulin extraction.