title: Hydrolysis of whey lactose by immobilized β-galactosidase in a bioreactor with a spirally wound membrane.
abstract: The β-galactosidase was covalently immobilized onto a modified polypropylene membrane, using glutaraldehyde. The optimal conditions for hydrolysis of lactose (4.7%) by immobilized β-galactosidase in a batch process were determined 13.6 U enzyme activity, 40°C, pH 6.8 and 10h. The obtained degree of hydrolysis was compared with results received by a free enzyme. It was found, that the lactose hydrolysis by an immobilized enzyme was 1.6 times more effective than the lactose hydrolysis by a free enzyme. It was determined that the stability of the immobilized enzyme was 2 times higher in comparison with the stability of free enzyme. The obtained immobilized system β-galactosidase/polypropylene membrane was applied to produce glucose-galactose syrup from waste whey. The whey characteristics and the different preliminary treatments of the whey were investigated. Then the whey lactose hydrolysis in a bioreactor by an immobilized enzyme on a spirally wound membrane was performed. The optimal membrane surface and the optimal flow rate of the whey through the membrane module were determined, respectively 100 cm(2) and 1.0 mL min(-1). After 10h, the degree of lactose hydrolysis was increased to 91%. The operation stability was studied. After 20th cycle the yield of bioreactor was 69.7%.
authors.affiliation: Rusenski University "Angel Kanchev", Filial Razgrad, Department of Biotechnology, Aprilsko vastanie Str.1, Razgrad, Bulgaria.
authors.forename: Nastya
authors.initials: N
authors.lastname: Vasileva
authors.affiliation: University "Prof. A.Zlatarov", Department of Biotechnology, Prof Y.Yakimov Str.1, 8010 Burgas, Bulgaria.
authors.forename: Yavor
authors.initials: Y
authors.lastname: Ivanov
authors.affiliation: Rusenski University "Angel Kanchev", Filial Razgrad, Department of Biotechnology, Aprilsko vastanie Str.1, Razgrad, Bulgaria.
authors.forename: Stanka
authors.initials: S
authors.lastname: Damyanova
authors.affiliation: Rusenski University "Angel Kanchev", Filial Razgrad, Department of Biotechnology, Aprilsko vastanie Str.1, Razgrad, Bulgaria.
authors.forename: Iliana
authors.initials: I
authors.lastname: Kostova
authors.affiliation: University "Prof. A.Zlatarov", Department of Biotechnology, Prof Y.Yakimov Str.1, 8010 Burgas, Bulgaria. Electronic address: godjevargova@yahoo.com.
authors.forename: Tzonka
authors.initials: T
authors.lastname: Godjevargova
mesh_terms: D019149:Bioreactors; D004800:Enzymes, Immobilized / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D007785:Lactose / Q000737:chemistry*; D008567:Membranes, Artificial; D011126:Polypropylenes / Q000737:chemistry; D013696:Temperature; D000067796:Whey / Q000737:chemistry*; D001616:beta-Galactosidase / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D008567:Membranes, Artificial; D011126:Polypropylenes; D001616:beta-Galactosidase; D007785:Lactose
keywords: Reactor with a spirally wound membrane; Whey lactose; β-Galactosidase