Ultrasonic study of the gelation of gelatin: phase diagram, hysteresis and kinetics

TL;DR

This study uses ultrasonic techniques to investigate the gelation process of gelatin, mapping phase transitions, hysteresis, and kinetics, providing insights into its structural and visco-elastic properties.

Contribution

It introduces ultrasonic measurement methods for characterizing gelatin gelation, including phase diagram construction and kinetic analysis, which are novel in this context.

Findings

Ultrasonic signatures confirm sol-gel transition and hysteresis effects.

Phase diagram of gelatin system was constructed based on ultrasonic data.

Ultrasonic models estimate sound speed and compressibility of gelatin.

Abstract

We map the ultrasonic (8 MHz) speed and attenuation of edible-grade gelatin in water, exploring the key dependencies on temperature, concentration and time. The ultrasonic signatures of the sol-gel transition, confirmed by rheological measurements, and incomplete gel formation at low concentrations, enable a phase diagram of the system to be constructed. Sensitivity is also demonstrated to the kinetics of gel formation and melting, and associated hysteresis effects upon cyclic temperature sweeps. Furthermore, simple acoustic models of the sol and gel state enable estimation of the speed of sound and compressibility of gelatin. Our results demonstrate the potential of ultrasonic measurements to characterise the structure and visco-elasticity of gelatin hydrogels.