For FTIR analysis of the protein, 300 µg of the protein were mixed with potassium bromide (KBr) using an agate mortar, and pressed into 7 mm diameter self-supporting disks using a load of 10 tons. FTIR spectra were acquired using a Cary 680 FTIR spectrometer (Agilent Technologies, CA, USA) by co-averaging 120 scans and at a resolution of 1 cm 1 . At least four spectra were measured for each formulation. The FTIR spectra of the pure excipients were recorded and subtracted from each sample spectrum, by a linear subtraction scaled to the excipient peak at 851 cm 1 . The recorded spectra were normalised based on the total area under the curve. To estimate the secondary structure composition, each spectrum was smoothed using a Savitsky-Golay derivative function fitted over 14 cm 1 and the second derivative of the amide I region from 1590 1620 cm 1 was calculated. Ten Gaussian peaks were fitted to the second derivative spectrum and the ratio of the peak areas compared to the total area under the curve was used to estimate the secondary structure content. 2.6. Solid State Nuclear Magnetic Resonance Spectroscopy (ssNMR) Solid state nuclear magnetic resonance spectroscopy was used to investigate the structural changes of the unheated (278 K) and heated (370 K) samples of F2, unheated (278 K) and heated (410 K) samples of F4, unheated (278 K) and heated (330 K) samples of F6 and unheated (278 K) and heated (370 K) samples of F7. 13 C CP-MAS spectra were acquired using a Bruker AVANCE 400 (Bruker UK Limited, Coventry, UK) equipped with a Bruker 4 mm CP/MAS 1 H/X BB probe at room temperature, operating at a magic angle spinning (MAS) rate of 12 kHz together with the SPINAL64-proton decoupling pulse sequence during acquisition. The cross polarisation (CP) efficiency was optimised using a glycine sample. For cross polarisation a ramped CP from 50 100% with a contact time of 2 ms was used. Data were acquired by averaging 1200 free induction decays containing 2494 complex data points with a total acquisition time of 25 ms and a relaxation delay of 5 s between individual scans unless indicated otherwise. Proton spin-lattice relaxation times T 1 were determined by inversion recovery with 13 C detection via CP. For each sample eight individual time points t were acquired (0.01, 0.05, 0.1, 0.2, 0.5, 1.0, 2.0 and 5.0 s).