title: From by-product to valuable components: Efficient enzymatic conversion of lactose in whey using β-galactosidase fromStreptococcus thermophilus.
abstract: β-Galactosidase fromStreptococcus thermophiluswas overexpressed in a food-grade organism,Lactobacillus plantarumWCFS1. Laboratory cultivations yielded 11,000 U of β-galactosidase activity per liter of culture corresponding to approximately 170 mg of enzyme. Crude cell-free enzyme extracts obtained by cell disruption and subsequent removal of cell debris showed high stability and were used for conversion of lactose in whey permeate. The enzyme showed high transgalactosylation activity. When using an initial concentration of whey permeate corresponding to 205 g L-1lactose, the maximum yield of galacto-oligosaccharides (GOS) obtained at 50°C reached approximately 50% of total sugar at 90% lactose conversion, meaning that efficient valorization of the whey lactose was obtained. GOS are of great interest for both human and animal nutrition; thus, efficient conversion of lactose in whey into GOS using an enzymatic approach will not only decrease the environmental impact of whey disposal, but also create additional value.
authors.affiliation: Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Geiger
authors.affiliation: Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria; Department of Biotechnology, Danang University of Technology, Nguyen Luong Bang 54, Danang, Viet Nam.
authors.forename: Hoang-Minh
authors.initials: HM
authors.lastname: Nguyen
authors.affiliation: Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Wenig
authors.affiliation: Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria; Department of Biochemistry and Food Biotechnology, Vietnam National University of Agriculture, Hanoi, Viet Nam.
authors.forename: Hoang Anh
authors.initials: HA
authors.lastname: Nguyen
authors.affiliation: Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Cindy
authors.initials: C
authors.lastname: Lorenz
authors.affiliation: Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Roman
authors.initials: R
authors.lastname: Kittl
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, N-1432 Ås, Norway.
authors.forename: Geir
authors.initials: G
authors.lastname: Mathiesen
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, N-1432 Ås, Norway.
authors.forename: Vincent G H
authors.initials: VG
authors.lastname: Eijsink
authors.affiliation: Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Haltrich
authors.affiliation: Food Biotechnology Laboratory, Department of Food Science and Technology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Thu-Ha
authors.initials: TH
authors.lastname: Nguyen
keywords: Galacto-oligosaccharides (GOS); Prebiotics; Transgalactosylation; Whey permeate; β-galactosidase