State diagrams of arabinoxylan-water binaries

• Published in: Thermochimica acta 2001-04, Vol.370 (1-2), p.83-89
• Main Authors: Fessas, Dimitrios, Schiraldi, Alberto
• Format: Article
• Language: English
• Subjects: Arabinoxylans; Biological and medical sciences; Cereal and baking product industries; Cryostability; DSC; Food industries; Fundamental and applied biological sciences. Psychology; Pentosans; State diagrams
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/S0040-6031(00)00783-8

Since Arabinoxylans are natural polysaccharides that seem promising candidates as cryostabilizers, the state diagram (i.e. the representation in the temperature-composition plan of the macroscopic phases) of their aqueous solutions seemed worth determining. Two lots of purified water extractable arabinoxylans (WEA) of different molecular mass (56 and 410kDa labeled as LMW-AX and HMW-AX, respectively) were used to prepare aqueous solutions of various composition. These were cooled below their freezing point and annealed for 2h at a suitable temperature before a DSC 5°Cmin−1 heating run aimed at determining their primary glass transition temperature, Tg′, and the onset of ice fusion. Once the corresponding composition, Cg′, was assessed, the main curves of the corresponding state diagram were drawn. As expected, the Tg′ value drawn for HMW-AX was higher (−17°C) than for LMW-AX (−35°C). The Cg′ was instead found close to 75% w/w for both HMW-AX and LMW-AX. The fictitiousness of this coincidence could be easily recognized by expressing the solute concentration in molar fraction, X: it was then possible to verify that, as expected, Xg′ for LMW-AX was one order of magnitude larger than for HLW-AX.