Antioxidant potential and α-galactosides content of unhulled seeds of dark common beans subjected to tempe-type fermentation with rhizopus microsporus var. chinensis and lactobacillus plantarum

Abstract

Dark common beans have beneficial nutritional and functional parameters but contain flatulence-producing α-galactosides. The aim of the research was to study the effect of modified tempe-type procedure (mixed-culture fermentation of unhulled seeds) on the antioxidant parameters and α-galactosides level in the product, as compared to raw and hydrothermally processed seeds. Soaking and cooking significantly lowered the antiradical activity and the reducing power of common beans. Tempe showed higher activity against OH (IC50 9.34 mg), DPPH and ABTS+ (on the average of 45%) and higher reducing power than the hydrothermally processed beans. Tempe contained 29% more soluble phenols (1.76 g kg-1-1 DM), 140% more condensed tannins (1.03 g kg-1 DM) and 30% more flavonoids (0.35 g kg-1 DM) than soaked and cooked seeds. The level of raffinose (0.031 g kg-1 DM), verbascose (0.027 g kg-1 DM) and stachyose (0.242 g kg-1 DM) in tempe was 67%, 53% and 57% lower, respectively.