Validation of Optimal Fourier Rheometry for rapidly gelling materials and its application in the study of collagen gelation

•Optimal Fourier Rheometry (OFR) is validated in applications involving rapidly gelling materials.•The Gel Point characteristics of collagen gels are measured, under near-physiological conditions, using OFR.•The stress relaxation characteristics of collagen gels are shown to depend markedly on collagen concentration. Rheological Gel Point measurements may incur errors in the case of rapid gelling systems due to the limitations of multiple frequency oscillatory shear techniques such as frequency sweeps and Fourier Transform Mechanical Spectroscopy, FTMS. These limitations are associated with sample mutation and data interpolation. In the present paper we consider how an alternative rapid characterisation technique known as Optimal Fourier Rheometry, OFR, can be used to study a rapidly gelling material, namely collagen at near physiological temperatures. The OFR technique is validated using a model reference gelling system whose GP characteristics have been widely reported. An analysis of the susceptibility of OFR measurements to rheometrical artefacts is made prior to its use in the study of rapid gelling collagen gels formed over a range of physiologically relevant collagen concentrations. The results of this OFR study are the first measurements of the stress relaxation characteristics of collagen gels performed in a single rheological experiment.