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

• Published in: Journal of thermal analysis and calorimetry Vol. 135; no. 5; pp. 2629 - 2634
• Main Authors: Ebara, Tomomi, Hagura, Yoshio, Kawai, Kiyoshi
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.03.2019; Springer; Springer Nature B.V
• Subjects: Analytical Chemistry; Chemistry; Chemistry and Materials Science; Ductile fracture; Ductile-brittle transition; Glass transition temperature; Hazelnuts; Inorganic Chemistry; Linear equations; Measurement Science and Instrumentation; Moisture content; Physical Chemistry; Polymer Sciences; Properties (attributes); Relative humidity; Rheological properties; Temperature; Texture; Thermomechanical analysis; Thermal mechanical analysis; Glass transition temperature; Texture; Hazelnut; Critical water content
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-018-7672-2

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 T g 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 T g of the samples was determined. Water plasticizing effect caused mechanical T g to decrease as the water content increased. The reduction in T g was analyzed using the Gordon–Taylor equation and linear equation, and the critical water contents (water content at mechanical T g  = 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.