Novel Process of Fermenting Black Soybean [Glycine max (L.) Merrill] Yogurt with Dramatically Reduced Flatulence-Causing Oligosaccharides but Enriched Soy Phytoalexins

Abstract

Black soybeans [Glycine max (L.) Merrill] were germinated under fungal stress with food grade R. oligosporus for 3 days and were homogenized and fermented with lactic acid bacteria (LAB) to produce soy yogurt. Fungal stress led to the generation of oxylipins [oxooctadecadienoic acids (KODES) isomers and their respective glyceryl esters] and glyceollinssa type of phytoalexins unique to soybeans. In soy yogurt, the concentrations of total KODES and total glyceollins were 0.678 mg/g (dry matter) and 0.953 mg/g, respectively. The concentrations of other isoflavones (mainly genistein and daidzein and their derivatives) in soy yogurt remained largely unchanged after the processes compared with the control soy yogurt. Germination of black soybean under fungal stress for 3 days was sufficient to reduce stachyose and raffinose (which cause flatulence) by 92 and 80%, respectively. With a pH value of 4.42, a lactic acid content of 0.262%, and a maximum viable cell count of 2.1 × 10 8 CFU/mL in the final soy yogurt, soy milk from germinated soybeans under fungal stress was concluded to be a suitable medium for yogurt-making. The resulting soy yogurt had significantly altered micronutrient profiles with significantly reduced oligosaccharides and enriched glyceollins.

Structure, trypsin inhibitor activity and functional properties of germinated soybean protein isolate

“…The soybean seed germination process was carried out according to the method described by Feng et al . (), with some modifications. Firstly, the selected soybean seeds were disinfected with 75% ethanol for about 1 min, and then were rinsed using deionised water for six times to wash away the ethanol.…”

The Role of Soy in Vegetarian Diets

“…Fermentation of soybeans, such as in the making of miso and natto, leads to the creation of some potentially interesting compounds not found in nonfermented foods [252,253], but there is scant evidence to suggest fermented foods are superior to nonfermented ones in any meaningful way; in fact, the opposite case can be made on the basis of limited epidemiologic data [7,254]. On the other hand, fermentation reduces oligosaccharide content, which may reduce flatulence [255,256]. …”

Yield stress and sensorial evaluation of soya yoghurts prepared from germinated soybeans

“…The absence of α-galactosidase in humans means that these components are not hydrolysed in the small intestine, but are instead degraded via fermentation in the colon by gas producing microorganisms. These fermentative processes proceed with the release of gas that causes flatulence and the accompanying unpleasant feelings (Feng et al 2008).…”