Agarose gelation beyond equilibrium through distributed kinetic pathways and apparent thermodynamic signatures

The gelation of agarose in aqueous solution is studied by differential scanning calorimetry (DSC) under non-isothermal cooling at different rates. The thermograms show a clear exothermic peak whose position and shape depend on the cooling rate, highlighting the coupling between the imposed thermal protocol and the intrinsic timescales of network formation. The sol-gel transition is described through a temperature- and rate-dependent degree of transformation, defined as the normalized fraction of exchanged enthalpy. This model-free parameter yields sigmoidal conversion curves that progressively shift and distort at higher cooling rates, indicating a deviation from quasi-equilibrium conditions. Extrapolation to zero cooling rate identifies a unique gelation temperature, independent of protocol and conversion level, thereby providing an operational gel point. The derivative of the conversion yields a kinetic profile whose broadening at high rates reflects cooperative, distributed, non-equilibrium gelation dynamics.