Role of inulin and its degradates in prebiotic effect of newly developed functional foodstuff

Complete text of publication follows. Inulin-type fructans can be found in more than 36.000 plant species and they are among the most abundantly occurring carbohydrates in nature. Inulin is a linear chain of fructose monomers having a terminal glucose moiety with an average degree of polymerisation (DP) of 10. Major goal of our study was to develop a new, inulin-containing functional food (biscuit) with pronounced prebiotic impact. Application of novel analytical and microbiological methods aimed at revealing of both heat degradation pathway and the exact prebiotic impact of inulin. Dependency of microbiological activity on the time-interval of thermal treatment was examined in cases of E. coli, Bifidobacterium and Enterococcus. 12 min of treatment at 190 deg C was the most efficient in order to acquire the most pronounced prebiotic effect. 90% of the original amount of inulin has been decomposed leading to a new product (biscuit) with multiplicated bacterium activating effect. Comparison of distinctive extraction and sample preparation protocols has been performed. Throughout our studies inulin was acquired from Chicorium intybus L. (chicory), Dahlia species (dahlia), Helianthus tuberosus (Jerusalem artichoke), and the samples were treated at 8 different temperatures for 9 distinctive time periods. Thermal treatments were carried out from 150 deg C up to 230 deg C. Mapping of the thermal degradation of the inulin was accomplished by means of HPLC-ELS-MS technique. Oligo-, and polymers deriving from inulin's heat degradation were isolated ranging from DP3 up to DP31. Various fructan oligomer degradates were identified directly with the exact number of fructose units, thus the entire decomposition pathway was revealed. Thermal degradation of inulin results in the formation of degradates activating the Bifidobacterium species 5 times more than the non-treated inulin. Major output of our study is that a new functional foodstuff with enhanced prebiotic effect is produced by thermal treatment of inulin. The activation of relevant microbes was justified by test experiments.