title: Lunasin and Bowman-Birk protease inhibitor concentrations of protein extracts from enzyme-assisted aqueous extraction of soybeans.
abstract: Lunasin and Bowman-Birk protease inhibitor (BBI) are two soybean peptides to which health-promoting properties have been attributed. Concentrations of these peptides were determined in skim fractions produced by enzyme-assisted aqueous extraction processing (EAEP) of extruded full-fat soybean flakes (an alternative to extracting oil from soybeans with hexane) and compared with similar extracts from hexane-defatted soybean meal. Oil and protein were extracted by using countercurrent two-stage EAEP of soybeans at 1:6 solids-to-liquid ratio, 50 °C, pH 9.0, and 120 rpm for 1 h. Protein-rich skim fractions were produced from extruded full-fat soybean flakes using different enzyme strategies in EAEP: 0.5% protease (wt/g extruded flakes) used in both extraction stages; 0.5% protease used only in the second extraction stage; no enzyme used in either extraction stage. Countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes was used as a control. Protein extraction yields increased from 66% to 89-96% when using countercurrent two-stage EAEP with extruded full-fat flakes compared to 85% when using countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes. Extruding full-fat soybean flakes reduced BBI activity. Enzymatic hydrolysis reduced BBI contents of EAEP skims. Lunasin, however, was more resistant to both enzymatic hydrolysis and heat denaturation. Although using enzymes in both EAEP extraction stages yielded the highest protein and oil extractions, reducing enzyme use to only the second stage preserved much of the BBI and Lunasin.
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University, Ames, Iowa 50011-1061, USA.
authors.forename: Juliana Maria
authors.initials: JM
authors.lastname: Leite Nobrega de Moura
authors.forename: Blanca
authors.initials: B
authors.lastname: Hernandez-Ledesma
authors.forename: Neiva Maria
authors.initials: NM
authors.lastname: de Almeida
authors.forename: Chia-Chien
authors.initials: CC
authors.lastname: Hsieh
authors.forename: Ben O
authors.initials: BO
authors.lastname: de Lumen
authors.forename: Lawrence A
authors.initials: LA
authors.lastname: Johnson
mesh_terms: D010936:Plant Extracts / Q000737:chemistry*; D030262:Soybean Proteins / Q000032:analysis* / Q000302:isolation & purification; D013025:Glycine max / Q000737:chemistry*; D014358:Trypsin Inhibitor, Bowman-Birk Soybean / Q000032:analysis* / Q000302:isolation & purification
chemical_list: C120514:GM2S-1 protein, soybean; D010936:Plant Extracts; D030262:Soybean Proteins; D014358:Trypsin Inhibitor, Bowman-Birk Soybean