Optimization of inulin extraction from Cynara scolymus L. root using response surface methodology (RSM)

Inulin is a low digestable or indigestible fiber which is found in various plants. Inulin amount ranging from 1% in Banana to more than 15% in Chicory roots changing. It has a positive impact on the composition of the intestinal flora, mineral absorption, blood lipid composition and prevents colon cancer. Artichoke (Cynara scolymus L.) is one of the most important sources of inulin. The aim of the present study was extraction of inulin from artichoke root and optimization of extraction conditions to achieve the highest extraction efficiency. For this purpose, the artichoke roots were collected from the research stead of Gorgan University of Agricultural Sciences and Natural Resources in september 2015 and inulin extraction with using of warm water solvent and response surface methodology (RSM)and central composite design (CCD) was performed. Response surface methodology in comparison to voluminous methods such as full factorial is preferred. In this technique for optimization of inulin extraction process, three variables extraction time (35-65 min), extraction temperature (55-95 °C) and the ratio of water to the roots (3:1 to 9:1)as independent variables were considered and their effect on the extraction efficiency of inulin were examined. After performing experiments, linear, 2FI and quadratic models on the inulin extraction yield were evaluated, also lack of fit test, coefficient of determination (R2)and Adjusted coefficient of determination (R2adjusted) for investigation the adequacy of the model were calculated. Study of the lack of fit test as well as R2 and ​​R2adjusted values were showed the suitability of quadratic model. This model was used to find the best condition of extraction process with maximum efficiency. Results showed that the optimum condition for extraction of inulin with highest extraction yield (8.01%) related to temperature (95 °C), time (35.67 min) and ratio of water to root (9:1) with desirability of (92%).