Flow behaviour of inulin-milk beverages: Influence of inulin chain length and of milk fat content

Abstract

Inulin is used either as a macronutrient substitute or as a supplement added in foods mainly for its nutritional properties. Chemically, inulin consists of a long chain made up of fructose molecules and one glucose molecule at one end. The fructose molecules are connected by β-(2-1) bonds and the last fructose is linked with a glucose by an α-(1-2) bond as in sucrose [1, 2]. The average molecular weight and degree of polymerisation of inulin depend on the source of inulin, the time of harvest and the process of production. In native chicory inulin, the number of fructose units linked together ranges from 2 to more than 60, with an average degree of polymerisation of the order of 10 and the high performance forms of inulin have an average degree of polymerisation of 25 [3]. The rheological behaviour of inulin and inulin-hydrocolloids mixtures in water were characterised by Bishay [4] who found a synergistic effect between inulin and calcium alginate. The objective of this work was to study the influence of the addition of inulin of different chain lengths on the flow behaviour of dairy beverages model systems with different milk fat content and with and without κ-carrageenan added.