Table 2.

FTIR peak assignment.

Wavenumber (cm−1)	Definition of the Spectra Assignment
3286	Overlapping –OH stretching vibrations and N–H stretching vibrations from peptide groups of proteins (amide A) [26]
3076 2959	CH3 asymmetric stretching vibrations from lipids with low contribution from proteins, carbohydrates and nucleic acids [28]
2930 2869	CH2 asymmetric and symmetric stretching vibrations from lipids with low contribution from proteins, carbohydrates and nucleic acids [29]
1652	C=O stretching vibrations from peptide backbone (amide I) [26]
1542	N–H bending vibrations from peptide groups (amide II) [26]
1450	CH2 bending (scissoring) vibrations from lipid acyl [27]
1397	CH3 bending vibrations from lipids and proteins [27]
1309 1240	C–N stretching mode of proteins, indicating mainly α-helical conformation (amide III) [30]