Preparation and characterisation of glyceollin‐enriched soya bean protein using solid‐state fermentation

Abstract

Summary Glyceollins, stress‐induced phytoalexins from parent soya bean isoflavones, were elicited with Aspergillus oryzae. This solid‐state fermentation facilitated the conversion of isoflavone glycosides into aglycones and glyceollins, which could mainly enrich in soya bean protein isolate (SPI) during protein preparation due to protein–polyphenol interactions. Glyceollin‐enriched SPI exhibited less flavour volatiles, higher solubility, lower whiteness and higher antioxidant activity than unfermented SPI. Fermented SPI was more easily to be digested during in vitro pepsin–trypsin digestion. This may be attributed to partial degradation of protein, especially α′ and α subunits of β‐conglycinin and acidic subunit of glycinin. The antioxidant activity of digestive products derived from fermented SPI was obviously enhanced with increasing digestion time due to simultaneous release of antioxidant peptides and glyceollins involved in the interior of protein molecule. These results suggest an effective technique for producing a nutrient‐enhanced SPI as novel functional ingredients applied in food industry.

Influence of plant growth regulators on key‐coding genes expression associated with phytochemicals biosynthesis and antioxidant activity in soybean (Glycine max (L.) Merr) sprouts

“…Vitamin C content and redox balance showed remarkable changes in embro and endosperm during germination in plants (Tommasi et al, 2001). Therefore, nutritional quality of fruits, vegetable and other plant based food materials is usually assessed by their vitamin C content (Cruzrus et al, 2011;Chen et al, 2017). Figure 1, revealed the effect of PGRs on vitamin C content in soybean sprouts.…”

Physicochemical properties of soy protein prepared by enzyme‐assisted countercurrent extraction

“…Unfortunately, most isoflavones in soy products, for example soy protein isolate (SPI), naturally exist in the form of glycosides. In fact, soy isoflavones could be bound with protein by noncovalent interactions during SPI preparation process (Rickert et al, 2004;Malaypally & Ismail, 2010;Chen et al, 2017).…”

“…It should be noted that acid precipitation process (pH 4.5) in the presence of NaCl could cause the absorption of some bad flavour volatiles to protein molecules (Samoto et al, 1998). Based on these problems, enzyme treatment and solid-state fermentation have been used to convert isoflavone glycosides and degrade phytic acid (Yang et al, 2015;Lu et al, 2016;Chen et al, 2017). In terms of protein flavour, alcohol leaching could effectively remove residual polar lipids of protein (Wu et al, 2011).…”