FTIR measurements of the neat BSA showed an ↵helix content of 15 ± 8% while the samples of F2 (both unheated and heated) contained 36 ± 10% and 41 ± 13% ↵-helix respectively. Additionally, FTIR measurements of the unheated BSA sample of F4 showed that it contains a higher content of ↵-helix compared to the neat BSA sample (40 ± 11% vs. 15 ± 8%) (see ESI), supporting that lyophilisation and the addition of excipients resulted in a conformational change to BSA which THz-TDS can detect.