Characterisation of inulin from chicory and salsify cultivated in Portugal

Abstract

Inulin and fructooligosaccharides (FOS) are important ingredients used in the food industry because of their diverse nutritional and functional properties. Among the sources of these compounds, chicory (Cichorium intybus L.) is one of the most important, due to its high content of inulin, which shows a high F/G ratio. As in several European countries, chicory is grown in Portugal where is used traditionally as a coffee substitute. However, studies have been carried out concerning the evaluation of the characteristics of the carbohydrate fraction of Portuguese chicory, to investigate its industrial potential as a raw material for the production of inulin, FOS and fructose. Salsify (Tragopogon porrifolius L.), another plant generally regarded as an inulin source, is also cultivated in the same regions of our country where it is used as a cooked vegetable. Carbohydrate constituents of chicory and salsify roots, mainly inulin and FOS, were submitted to a physical-chemical analysis by HPLC and DSC (Differential Scanning Calorimetry). The viscosities of the gels produced from both inulins were also evaluated. From HPLC results it was apparent that great differences exist between the inulin sources, mainly in degree of polymerisation which was higher in chicory. Endotherms showed that both peak temperature and enthalpy values of the transition were different, the latter being much higher for salsify. KEYWORDS: Physical-chemical analysis of inulin; chicory; salsify.