| Abstract
| - The effect of different polysaccharides on the rotational (Drot) and translational diffusion (Dtrans)coefficients of small molecules in concentrated systems (sucrose solutions) was investigated. Dextran(1 or 10% w/w) with different molecular masses (from 104 to 2 × 106 Da), gum arabic, or pullulanwas added to solutions of sucrose (57.5% w/w). Viscosity measurements of the diffusion mediumstudied (sucrose and sucrose plus polysaccharide) were made using a Rheometric Scientific viscometerin a temperature range from 20 to −10 °C. The rotational mobility of nitroxide radicals (Tempol)dispersed in the concentrated systems was measured by electron spin resonance. The translationaldiffusion coefficient of fluorescein was determined by the fluorescence recovery after photobleachingmethod. The studied temperature range for the latter two techniques was from 20 to −16 °C. Forthese conditions of concentration and temperature, there was no ice formation in the samples. Noeffect of the molecular mass of dextran on Drot and Dtrans was observed when solutions with thesame dry matter content were compared. Only pullulan and gum arabic, at 10%, had a significanteffect on Dtransof fluorescein. Temperature and total dry matter content were observed to be themost important factors controlling Drot and Dtrans in these concentrated systems. Keywords: Polysaccharide; sucrose; rotational and translational mobility; diffusion coefficient;subzero temperatures
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