Methods of isolating different structural fraction of inulin from chicory plants and physiochemical properties of the resulting compunds

Inulin, belongs to a class of dietary fibers known as fructans, is a heterogeneous collection of fructose polymers linked by β(2 →1) bonds. This prebiotic compound is increasingly used in processed foods because of its health benefit effects, nutritional and technological characteristics. Native inulin is commercially extracted from chicory (Cichorium intybus L.) with the degree of polymerization (DP) ranges from 2 to 60. The chain length affects on its technological properties in food products. Short-chain oligofructose, contain 2–8 links per a saccharide molecule, are more soluble and sweeter than native inulin, so they can be used as sugar replacers, while long-chain inulin, contain 10-60 links per saccharide molecule, is more thermally stable, less soluble and more viscous than the native inulin and it is used as a fat substitute in different food products. The majority of researchs done on prebiotics are based on the full-spectrum inulin with no fractionation. In this research, fractionation of inulin to short- and long-chain lengths was studied using different treatments including concentrations of ethanol solvent (60 and 90%), crystallization and precipitation of aqueous solution in -20°C, and ultrafiltration using 4 kilo-dalton UF cut off. Effect of the treated methods on the degree of polymerization, yield of extraction and physicochemical properties of the compounds were compared.

Keywords:

Inulin , oligofructose , ethanol , crystallization , ultrafiltration , prebiotics