Valorization of Glycine max (Soybean) Seed Waste: Optimization of the Microwave-Assisted Extraction (MAE) and Characterization of Polyphenols from Soybean Meal Using Response Surface Methodology (RSM)

Table 7

Peak wave numbers and assignation.

Wave number (cm^−1)	Vibration	Assignment	Reference
3275	–C–OH (stretching)	Water and polysaccharides	[30, 31]
2928	–C–H (stretching)	Aliphatic chain: lipids	[30]
		Isoflavones (daidzein and genistein)	[32]
2146	–NH2(stretching)	Free amino acid and/or derivatives	[33]
1579	–C=C (skeletal)	Aromatic compounds and flavonoids
1393	–C–H (bending); –O–H (deformation); –C–O (deformation)	Phenols	[34]
1272	In plane = C–H	Phenols, flavonoids, or aromatic compounds	[35]
1040	Ester –C–O (stretching)	Glycosidic groups	[36]
991	Unidentified
922	–C–C (stretching)	Alkane lipids, aminiacids, and proteins
510	Phenol ring (torsion)	Phenols	[37]
473	O–S–O (bending)	SO^−4 group	[38]
409	In plane –C–OH (bending)	Phenols	[33]