Characterization of the thermal behavior and structural properties of a commercial high-solids confectionary gel made with gelatin

Abstract

Gelatin plays a critical role in controlling the stability and texture of high-solids gels (HSGs), widely used in confectionery products and nutrient delivery systems. Most gelatin studies have been done on dilute solutions and films, rather than HSGs. Thus, the objectives of this study were to determine the: 1) thermal and structural characteristics of gelatin in a high-solids confectionary gel, 2) effect of renaturation temperature on reformation of gelatin helical structure, and 3) effect of time on loss and reformation of gelatin helical structure. Gelatin HSGs thermal and structural characteristics were investigated using differential scanning calorimetry (DSC), powder x-ray diffraction, and powder x-ray diffraction with total scattering pair distribution function analysis, respectively. The gelatin HSG DSC thermogram exhibited two thermal events: a glass transition and an endothermic peak associated with the helix-coil transition. Based on these results, the helix-coil transition was identified as a thermal denaturation event, not a melting event. The effect of renaturation temperature on gelatin reformation and the effect of time on the loss and reformation of triple-helix gelatin structure were determined using isothermal-DSC. Onset and peak denaturation temperatures increased with renaturation temperature, whereas the amount of triple-helix structure reformed increased with renaturation temperature up to 22 °C, then decreased. Both loss and renaturation of triple-helix structure were time-dependent processes. These results support the development of gelatin HSGs with controlled thermal stability and textural properties and contribute to solving the technical challenges associated with replacing gelatin in HSGs through enhanced understanding, obtained herein, of gelatin's thermal and structural characteristics.