Effect of water content on the glass transition and textural properties of hazelnut.

Ebara, Tomomi; Hagura, Yoshio; Kawai, Kiyoshi

This study is based on the assumption that the change in the texture of hazelnut, induced by water sorption or desorption, can be derived from the glass transition. No previous study has investigated the glass transition properties of hazelnuts. This study aimed to investigate the effect of water content on the glass transition and textural properties of a roasted hazelnut product. Water content of the sample was adjusted in various relative humidity conditions, and the mechanical glass transition temperature Tg was investigated using thermal rheological analysis (TRA), a type of thermomechanical analysis. The TRA curve exhibited a clear force drop induced by the glass transition, and mechanical Tg of the samples was determined. Water plasticizing effect caused mechanical Tg to decrease as the water content increased. The reduction in Tg was analyzed using the Gordon-Taylor equation and linear equation, and the critical water contents (water content at mechanical Tg = 25 °C) were obtained. The fracturing properties of the hazelnut changed from brittle to ductile at the critical water contents. This suggested that the change in the texture of hazelnut can be characterized by the glass transition.

HAZELNUTS; WATER content of glass; GLASS transitions; THERMOMECHANICAL properties of metals; LINEAR equations

Journal of Thermal Analysis & Calorimetry, 2019, Vol 135, Issue 5, p2629

1388-6150

Academic Journal

10.1007/s10973-018-7672-2