Studies on the physicochemical properties of inulin and inulin oligomers

Inulin, Raftiline(R) ST, Raftilose(R) P and oligofructose in aqueous solutions were investigated at 2.5, 5, 10, 15, 17.5, 20 and 25 g of solute in 100 g of water by physicochemical measurements in order to obtain molecular weights, reducing activities, apparent specific volumes, isentropic apparent specific compressibilities, and H-1-NMR pulse relaxation times (TI values). Molecular weights have been found to range from 340 to 4620 g mol(-1). Raftilose(R) P is the only sample which shows reducing capacity and may be expected to be susceptible to the Maillard reaction. Apparent specific volumes lie within the sweet range 0.60-0.64cm(3) g(-1) and increase with degree of polymerisation (DP); this behaviour describes increasing displacement of water as molecular weight increases. Isentropic apparent specific compressibilities increase as concentration of solute, molecular weight and DP increase, showing reduced solute-water affinity. T-1 values decrease with increasing molecular weight and concentration as a result of increased order of protons and reduced water mobility. (C) 1999 Elsevier Science Ltd. All rights reserved.