Comparative Analysis of Proximate, Nutritional, and Phytochemical Profiles of Soybean Varieties Using FTIR and HPLC

Soybean is an important legume crop having a highly nutritious profile. This study was performed to compare the phytochemical and nutritional profiles of various soybean varieties cultivated locally in Pakistan along with the quantification of isoflavone aglycones (Daidzein, Genistein, Glycitein) via HPLC and chemical composition analysis through FTIR. Three soybean varieties were selected, i.e., Ajmeri, Willium-82, and Rawal-I. The proximate composition of each soybean variety (moisture, fat, protein, and minerals), phytochemical analysis (TPC and TFC), and antioxidant analysis (FRAP and ABTS) of soybean varieties revealed significant variation (p < 0.05) in results. Moisture varied from 9.45%–10.45%, protein 33.72%–37.25%, fat 19.04%–21.99%, ash 4.49%–5.55%, and NFE (11.29%–15.14%). Phytochemical analysis revealed TPC in the range 1.35–2.95 (mg GAE/g), TFC 0.44–1.68 (mg CE/g), DPPH 4.21–6.12, FRAP 11.21–14.51, and ABTS 22.15–33.05 (mg TE/g) each with significant variation p < 0.05, respectively. HPLC chromatogram showed the presence of isoflavone daidzein ranging from 935.6–515.2 μg/g, glycitein 72.2–62.4 μg/g, and genistein 1071.2–320.4 μg/g in each variety. FTIR spectra of soybean varieties indicated the existence of multiple functional groups seen through the evident stretching of carbon, oxygen, and nitrogen bonds. The lipoxygenase activity in each soybean variety exhibited inhibition potential; maximum inhibition was found in LOX-2. Overall, the nutritional and phytochemical profile of Ajmeri was found to be better than that of other varieties used in the study.