title: Soybean bio-refinery platform: enzymatic process for production of soy protein concentrate, soy protein isolate and fermentable sugar syrup.
abstract: Soybean carbohydrate is often found to limit the use of protein in soy flour as food and animal feed due to its indigestibility to monogastric animal. In the current study, an enzymatic process was developed to produce not only soy protein concentrate and soy protein isolate without indigestible carbohydrate but also soluble reducing sugar as potential fermentation feedstock. For increasing protein content in the product and maximizing protein recovery, the process was optimized to include the following steps: hydrolysis of soy flour using an Aspergillus niger enzyme system; separation of the solid and liquid by centrifugation (10 min at 7500×g); an optional step of washing to remove entrapped hydrolysate from the protein-rich wet solid stream by ethanol (at an ethanol-to-wet-solid ratio (v/w) of 10, resulting in a liquid phase of approximately 60 % ethanol); and a final precipitation of residual protein from the sugar-rich liquid stream by heat treatment (30 min at 95 °C). Starting from 100 g soy flour, this process would produce approximately 54 g soy protein concentrate with 70 % protein (or, including the optional solid wash, 43 g with 80 % protein), 9 g soy protein isolate with 89 % protein, and 280 ml syrup of 60 g/l reducing sugar. The amino acid composition of the soy protein concentrate produced was comparable to that of the starting soy flour. Enzymes produced by three fungal species, A. niger, Trichoderma reesei, and Aspergillus aculeatus, were also evaluated for effectiveness to use in this process.
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH, 44325-3906, USA.
authors.forename: Abdullah Al
authors.initials: AA
authors.lastname: Loman
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH, 44325-3906, USA.
authors.forename: S M Mahfuzul
authors.initials: SM
authors.lastname: Islam
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH, 44325-3906, USA.
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH, 44325-3906, USA. Lukeju@uakron.edu.
authors.forename: Lu-Kwang
authors.initials: LK
authors.lastname: Ju
mesh_terms: D001234:Aspergillus niger / Q000254:growth & development*; D066248:High Fructose Corn Syrup / Q000737:chemistry*; D030262:Soybean Proteins / Q000737:chemistry*; D013025:Glycine max / Q000737:chemistry*; D014242:Trichoderma / Q000254:growth & development*
chemical_list: D066248:High Fructose Corn Syrup; D030262:Soybean Proteins
keywords: Bio-refinery; Soy flour; Soy protein concentrate; Soy protein isolate; Sugar