Process optimisation for fractionating Jerusalem artichoke fructans with ethanol using response surface methodology

Optimal conditions for fructan precipitation from Jerusalem artichoke concentrate by adding ethanol were established by response surface methodology. The combination of the starting syrup concentration (9.9–40 °B), ethanol-to-syrup (E/S) ratio (2.3:1–15.7:1) and precipitation temperature (3.1–62 °C) was varied at design points of a central composite rotatable design. Significant regression models describing the changes of average chain length, fructan precipitation yield and purity value of fructans were developed with the coefficient of determination greater than 0.8. The results suggested that higher syrup concentration resulted in an increased fructan yield, but further increase in concentration had a reverse effect on average chain length and purity values. The optimum conditions for fractionating fructan composition by ethanol were estimated to be 32 °B initial syrup concentration, E/S ratio of 13 and temperature of 42 °C.