Solid-state fermentation with probiotics and mixed yeast on properties of okara

Abstract

The effect of solid-state fermentation with compound probiotics and two types of yeast (Saccharomyces cerevisiae and Hansenula sp.) on the composition and selected quality attributes of okara were studied. Four different fermentation schemes, i.e., compound probiotics fermentation (P), mixed yeast (Saccharomyces cerevisiae and Hansenula sp.) fermentation (SH), co-fermentation of compound probiotics and mixed yeast (P + SH) and two-stage fermentation of compound probiotics and mixed yeast (P-SH) were comparatively assessed for their proximate composition, abilities to improve selected physicochemical, antioxidant, functional properties and sensory attributes (flavor and taste) of okara. The results showed that all the fermentation schemes could significantly improve the proximate composition, physicochemical as well as antioxidant activities and sensory attributes of okara. The bitterness and astringency of the okara were also reduced. The P-SH samples contained crude fiber of 12.0 g/100 g dry sample, total phenols of 154 mg gallic acid equivalence/100 g dry sample, free amino acids of 3.80 g/100 g dry sample. The DPPH free radical scavenging capacity and ABTS free radical scavenging capacity of the P-SH samples were 776 mg Trolox equivalence/100 g dry sample and 487 mg Trolox equivalence/100 g dry sample, respectively. The P + SH sample produced more alcohol, ester and other important flavoring substances than the other three methods. However, the P + SH sample had a relatively acidic taste.