Carbohydrates in Jerusalem artichoke powder suspension

Purpose - The aim of this study was to evaluate the influence of temperature and action time on the extraction rate of carbohydrates of Jerusalem artichoke concentrate powder and inactivation of inulin during boiling and sterilization. Design/methodology/approach - Water suspension of Jerusalem artichoke concentrate (5 g/100 ml) at 25, 50 and 100°C was tested after 5, 15, 30 and 60min to determine the content of inulin, glucose, fructose and sucrose and evaluate the extraction rate. The stability of inulin was studied after boiling and sterilization at 120°C during 1, 2 and 3 h. The extraction rate was evaluated by Fourier-Transform Infrared (FT-IR) spectroscopy as well. Findings - It was shown that extraction of soluble carbohydrates - fructose, glucose, sucrose and inulin, from water suspension of Jerusalem artichoke concentrate was practically completed in 5min at 25°C. The extraction rate was not significantly influenced by temperatures lower than 100°C. Inulin was stable during boiling for 1 h but sterilization for 1h caused significant losses. Infrared spectral analysis of soluble and insoluble fractions showed that inulin was practically fully extracted. Originality/value - The paper shows that inulin can be easily extracted from Jerusalem artichoke concentrate powder even at 25°C and it maintains for 60 min at temperatures up to 100°C, nevertheless boiling or sterilization at higher temperatures for longer time causes significant loses of inulin and consequently the functional quality of Jerusalem artichoke powder. These results must be taken into account when applying inulin concentrates as functional food components.