Abstract: The extraction and purification of inulin from Jerusalem artichoke grown in the saline-alkaline soil of Yancheng, Jiangsu province. The ash content of the botanic material was higher than those previously reported in the literature for Jerusalem artichoke samples from Fujiang province and Gan county, Jiangxi province. Twice repeated extraction for 40 min each time at 90 ℃ with a 15-fold volume of water proved optimal, and the resulting extraction efficiency was 89.56%. Ultrafiltration membrane separation with10 kD MWCO membrane could more effectively remove macromolecular substances such as protein and pectin from the obtained inulin extract when compared with the conventional phosphate-lime milk method, and the removal rate of protein and the retention ratio of inulin were improved by 27.12% and 13.41%, respectively. Polymerization degree analysis of different MWCO (10000, 5000, 2500 D and 340 D) fractions of the inulin extract showed that the polymerization degrees of inulin were varied from 16 to 60, which accounted for 76.1% of the total inulins. The optimal decoloration conditions for the inulin extract were activated carbon dosage of 5 g/L, decoloration temperature of 60 ℃ and decoloration time of 20 min. Under these conditions, the decoloration efficiency and the recovery of inulin were 92.87% and 91.63%, respectively. Therefore, ultrafiltration can greatly reduce the separation procedure due to convenience and rapidity and fewer procedures, thus showing a very promising prospect for industrial applications.

Key words: saline-alkaline beach, Jerusalem artichoke, inulin, extraction and purification, degree of polymerization