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

• Published in: Food hydrocolloids Vol. 26; no. 1; pp. 99 - 107
• Main Authors: Parker, N.G., Povey, M.J.W.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2012; Elsevier
• Subjects: acoustics; Attenuation; Biological and medical sciences; Compressibility; Food additives; Food industries; Foods; Fundamental and applied biological sciences. Psychology; Gelatin; Gelatins; gelation; Gel–sol transition; General aspects; hydrocolloids; Hysteresis; Melting; Phase diagrams; Rheology; Sol gel process; temperature; Ultrasound; Gel–sol transition; Gelatin; Rheology; Ultrasound; Phase diagram; Gelation; Kinetics; Sol gel transition; Gel-sol transition; Rheological properties
• ISSN: 0268-005X; 1873-7137
• DOI: 10.1016/j.foodhyd.2011.04.016

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. [Display omitted]