Thermal and mechanical characteristics of a glassy food model based on cassava starch

Abstract

A food model was formulated in this work by blending cassava starch with small amounts of protein (6%), corn oil (4.5%) and sugar (6%). The calorimetric and mechanical properties of this realistic food model were studied as a function of moisture content. An anti-plasticization behavior of the food model at moisture contents lower than 9% was detected by increases in the glass transition temperature (Tg) values. Higher moisture contents induced a strong reduction in Tg values. The presence of hydrophilic groups was responsible for both behaviors. Tensile tests revealed that the glassy food model was brittle, while neat glassy starch was ductile under similar moisture contents. This was probably due to the presence of protein aggregation during thermomoulding, as previously reported in starchy cereal materials. The composition of the food model can be tailored to control water sorption, thermal transitions, and mechanical properties of the food system considered here.

Keywords

• Food model
• Cassava starch
• Glass transition
• Starch crystallization
• Mechanical properties
• Brittle-ductile transition