Comparative Evaluation of Antioxidant, Phenolic, Flavonoid, Protein, And Isoflavone Profiles in Commercial Soy Products: A Multi-Methodological Approach
Comparative analytical study reveals distinct antioxidant, protein, and isoflavone profiles across commercial soy foods, highlighting significant nutritional variability from processing.
Key Points
To compare the antioxidant capacity, total phenolics, flavonoids, protein content, and individual isoflavone profiles across five common commercial soy products.
Analyzed five commercial soy products: soy milk, soy cheese, soy flour, soy ground meat, and soybean sprouts.
Quantified antioxidant capacity and phenolics using spectrophotometric assays (CUPRAC, ABTS, Folin-Ciocalteu, AlCl3/NaNO2), profiled isoflavones using HPLC, and determined protein content via Lowry and Cu(II)-neocuproine methods.
Total antioxidant capacity ranged from 11.54 ± 0.03 to 18.18 ± 0.16 mmol TE 100 g⁻¹ via CUPRAC and 14.95 ± 0.46 to 21.53 ± 0.10 mmol TE 100 g⁻¹ via ABTS, with soy milk showing the highest activity in both assays.
Protein content was highest in soy flour (63.02 ± 0.95 g 100 g⁻¹) and soy ground meat (59.40 ± 1.46 g 100 g⁻¹), while total phenolics ranged from 10.51 ± 0.08 to 18.27 ± 0.03 mmol GA 100 g⁻¹.
HPLC profiling revealed distinct isoflavone dominance per food type: genistin predominated in soy milk and flour, genistein in soy cheese and sprouts, and daidzein in soy ground meat.