3.4. Analysis of the Functional Groups of Gelatin Peptides via FTIR Spectroscopy

FTIR spectroscopy was performed with a resolution of 4 cm⁻¹ over the range of 4000–400 cm⁻¹ using a UV spectrometer (Thermo Nicolet iS5, Thermo Fisher, Waltham, MA, USA). Briefly, 2 mg of peptide powder and 200 mg of dried KBr were mixed to prepare the sample pellets. The pellets were placed in a sample compartment and measured 32 times at a scanning speed of 2.8 mm/s. After background correction (dried KBr spectrum used as background), the sample spectra were obtained.