Thermo-Mechanical Properties of Soft Candy: Application of Time-Temperature Superposition to Mimic Response at High Deformation Rates

Abstract

Soft candy primarily consists of an amorphous sugar matrix with highly adhesive and cohesive characteristics, which is generated by rapid cooling of a supersaturated sugar solution. The integration of fondant in soft candy leads to a partial recrystallization of the amorphous sugar so that the dispersed sugar crystals disrupt the continuous amorphous phase; this lowers cohesiveness, and creates a short texture that is responsible for a more brittle fracture. Final processing (e.g., cutting and packaging) is usually done at temperatures between 25 and 45 °C and short time scale. This study analyzed the effects of temperature and time scale on thermo-mechanical properties of different types of soft candy. The application of time-temperature superposition principle on small amplitude oscillatory shear experiments resulted in master curves that covered a frequency window up to 105 rad/s, hence a time scale that is relevant in rapid processing. The respective shift factors depend on material properties, and a main factor of influence is the presence of a crystalline phase. Simple penetration and tensile tests give additional information on material behavior, especially with respect to effects of temperature on adhesiveness and cohesiveness. The results of the study provide support for further optimizing soft candy formulations to ensure rapid and undisturbed processing.