Impact of soaking and germination durations on antioxidants and anti-nutrients of black and yellow soybean (Glycine max. L) varieties

Abstract

From nutritional point of view, the nutrient-anti-nutrient homeostasis determines the food quality and germination, a simple household process is potent enough to alter this balance. This study was conducted in black (Kalitur) and yellow (Pusa 9712) soybean varieties comparing the effect of soaking and germination on various antioxidants (total phenols, flavonoids, Vitamin C and total antioxidant capacity) and anti-nutrients (tannins, phytate, RFOs and trypsin inhibitors) on them. A significant (P < 0.05) decrease in the levels of total phenols (11 %, 6 %), total flavonoids (9 %, 5 %), condensed tannins (16 %, 14 %), phytates (13 %, 10 %), RFOs (11 %, 9 %), trypsin inhibitors (9 %, 8 %) and an increase in the levels of Vitamin C (62 %, 78 %) and the total antioxidant capacity (51 %, 71 %)in both Kalitur as well as Pusa 9712 respectively were observed after soaking. Further on comparingthe controls with different germination durations,maximum up to 72 h resulted insignificant (P < 0.05) reductions in the levels of tannins (68 %, 50 %), phytates (65 %, 49 %), RFOs (60 %, 45 %) and trypsin inhibitors (70 %, 57 %),were observed in both black and yellow soybean varieties respectively. An increase in the total polyphenols (17 %, 10 %), flavonoids (21 %, 11 %), Vitamin C (403 %, 308 %) and antioxidant capacity (410 %, 311 %) was however observed in the black and yellow soybean respectively compared to controls. The results implicated the role of the germination and an increase in its duration in reducing the anti-nutrients, enriching the antioxidants and thus improving the nutritive value of soy sprouts. Sprouts being a part of the present diet conscious society, 72 h old black soybean sprouts can be considered as better substitutes than their yellow counterparts.