Optimizing Dough Proofing Conditions To Enhance Isoflavone Aglycones in Soy Bread

Abstract

Native beta-glucosidase activity in soy bread can convert isoflavone glucosides to aglycones during proofing, and this study determined the time-temperature dependence of this process. Samples were taken every hour for 4 h during proofing at 22, 32, and 48 degrees C to determine beta-glucosidase activity and isoflavone profiles of the dough. After 1-2 h, the beta-glucosidase activity increased 43-84% achieving a plateau value at 22 degrees C but declining when proofed beyond 2 h at 32 degrees C and 48 degrees C. Large increases in aglycones and corresponding decreases in the simple glucosides were observed during proofing. The level of malonyl-glucosides decreased 3-15%, and acetyl-glucosides were fairly constant. The two higher temperatures drove more rapid conversion: 70-73% of simple glucosides in 2-4 h. The extent of conversion in the early proofing periods corresponded to beta-glucosidase activity. The optimum time-temperature protocol was 2 h at 48 degrees C resulting in a rapid, high conversion.

Phytochemical profiles of black and yellow soybeans as affected by roasting

“…The external environment variations such as heat, acid, alkaline, and enzymes can accelerate the inter-conversion reactions of isoflavones. [18] The daidzin, genistin, and glycitin amount in the current research was found to be increased. A previous study showed a conversion between isoflavones from malonyl derivatives to actetyl derivatives and β-glucosides after roasting.…”

Novel isoflavone diglycoside in groundnut (Apios americana Medik)

“…Further studies are needed to elucidate the nature of groundnut isoflavones, including changes in the content of genistein-7-O-genitiobioside in groundnuts during crop growth. Given the previous findings in soybeans revealing that their isoflavone composition varies depending on the processing methods (Grün et al, 2001;Riedl, Zhang, Schwartz, & Vodovotz, 2005;Yin, Li, Liu, Saito, & Tatsumi, 2005), along with the potential of groundnuts as an important isoflavone source, the effects of processing methods and storage conditions on the groundnut isoflavone composition also merit further research. Moreover, further analysis is required to determine the molecular structures of other components (peaks) isolated from the groundnut extract along with peak-1.…”

Hydrolysis of soybean isoflavone glycosides by a thermostable β-glucosidase from Paecilomyces thermophila

“…The endogenous b-glucosidase activity in soybean can convert isoflavone to aglycones during proofing. The level of malonyl glycosides decreased 3-15% whereas that of acetyl glycosides was fairly constant (Riedl et al, 2005). Most commonly, previous studies suggest that the unstable malonyl glycosides can easily be transformed into less conjugated forms by a thermal process (Barbosa et al, 2006;Coward et al, 1998).…”

“…Soybean isoflavones have attracted considerable attention for their health benefits in the prevention of cancer, osteoporosis, postmenopausal syndromes and hypercholesterolaemia (Nielsen & Williamson, 2007;Setchell et al, 2002). The content and composition of these isoflavones vary in soybean foods, depending on the soybean varieties and processing techniques, such as heat treatment and fermentation (Anderson & Wolf, 1995;Barbosa, Lajolo, & Genovese, 2006;Chun, Kim, & Kim, 2008;Coward, Smith, Kirk, & Barnes, 1998;Riedl, Zhang, Schwartz, & Vodovotz, 2005;Yamabe, Kobayashi-Hattori, Kaneko, Endo, & Takita, 2007).…”

“…There is interest in increasing the amounts of isoflavone aglycones in soy products. Some authors have reported that the isoflavone glycosides were hydrolysed into their corresponding aglycones during the fermentation of soybean foods, such as tempeh, soy bread, soymilk, miso and douchi (Anderson & Wolf, 1995;Chun et al, 2008;Kuo, Cheng, Wu, Huang, & Lee, 2006;Riedl et al, 2005;Wang et al, 2007;Yamabe et al, 2007). There are many reports of the deglycosylation of isoflavone glycosides during fermentation by Saccharopolyspora erythraea, lactic acid bacteria, Bifidobacteria, basidiomycetes and Bacillus subtilis through their b-glucosidase activities in soy products (Chun et al, 2008;Hessler, Larsen, Constantinou, Schram, & Weber, 1997;Kuo et al, 2006).…”