title: Aggregation of soy protein-isoflavone complexes and gel formation induced by glucono-δ-lactone in soymilk.
abstract: This study investigated the glucono-δ-lactone (GDL)-induced aggregation of isoflavones and soy proteins in soymilk. High-performance liquid chromatography (HPLC) analysis indicated that isoflavones mixed with β-conglycinin (7S) and glycinin (11S) proteins formed 7S-isoflavone and 11S-isoflavone complexes in soymilk supernatant fraction (SSF). Most of the soy protein-isoflavone complexes then precipitated into the soymilk pellet fraction (SPF) following the addition of 4 mM GDL, whereupon the pH value of the soymilk dropped from 6.6 to 5.9. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and HPLC analysis suggest that the addition of 4 mM GDL induced the aggregation of most 7S (α', α and β subunits), 11S acidic and 11S basic proteins as well as isoflavones, including most aglycones, including daidzein, glycitein, genistein and a portion of glucosides, including daidzin, glycitin, genistin, malonyldaidzin and malonylgenistin. These results provide an important reference pertaining to the effects of GDL on the aggregation of soy protein-isoflavone complexes and could benefit future research regarding the production of tofu from soymilk.
authors.affiliation: Department of Food Science, Fu Jen Catholic University, Taipei 242, Taiwan.
authors.forename: Sheng-Yang
authors.initials: SY
authors.lastname: Hsia
authors.affiliation: Department of Food Science, Fu Jen Catholic University, Taipei 242, Taiwan.|Ph.D. Program in Nutrition &Food Science, Fu Jen Catholic University, Taipei 242, Taiwan.
authors.forename: Yu-Hsuan
authors.initials: YH
authors.lastname: Hsiao
authors.affiliation: National Research Institute of Chinese Medicine, Ministry of Health and Welfare, Taipei 11221, Taiwan.
authors.forename: Wen-Tai
authors.initials: WT
authors.lastname: Li
authors.affiliation: Department of Food Science, Fu Jen Catholic University, Taipei 242, Taiwan.|Ph.D. Program in Nutrition &Food Science, Fu Jen Catholic University, Taipei 242, Taiwan.
authors.forename: Jung-Feng
authors.initials: JF
authors.lastname: Hsieh
mesh_terms: D055598:Chemical Phenomena; D011232:Chemical Precipitation; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005782:Gels / Q000737:chemistry*; D005942:Gluconates / Q000737:chemistry*; D007529:Isoflavones / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D011485:Protein Binding; D011489:Protein Denaturation; D055503:Protein Multimerization; D030262:Soybean Proteins / Q000737:chemistry*
chemical_list: D005782:Gels; D005942:Gluconates; D007529:Isoflavones; D007783:Lactones; D030262:Soybean Proteins; C010730:beta-glucono-1,5-lactone