Thermal properties of agave fructans (Agave tequilana Weber var. Azul)

Thermal properties of agave (A. tequilana Weber var. Azul) at different water contents were investigated. HP-TLC results showed a complex mixture of mono-, di-, oligo, and polysaccharides in agave fructans samples. The thermal decomposition temperatures were observed below to 200 °C. Modulated-differential scanning calorimetry studies showed a glass transition and a relaxation enthalpy processes in agave fructans. Samples with the highest moieties of monosaccharides showed the lower glass transition temperatures (Tg). The moisture sorption isotherm of agave fructans was determined at 20 °C and fitted to the GAB model. Gordon–Taylor equation was used to fit the Tg experimental data as a function of water content. Agave fructans was found to be an amorphous material. At low water activity (aw) values (<0.4), agave fructans remained in a powdered amorphous state; and at intermediate aw (0.4–0.75) collapsed and caked; and at high aw (>0.75) changed in a highly viscous liquid-like solution.