title: Optimization of an innovative hollow-fiber process to produce lactose-reduced skim milk.
abstract: The research field for applications of lactose hydrolysis has been investigated for several decades. Lactose intolerance, improvement for technical processing of solutions containing lactose, and utilization of lactose in whey are the main topics for development of biotechnological processes. We report here the optimization of a hollow-fiber membrane reactor process for enzymatic lactose hydrolysis. Lactase was circulated abluminally during luminal flow of skim milk. The main problem, the growth of microorganisms in the enzyme solution, was minimized by sterile filtration, ultraviolet irradiation, and temperature adjustment. Based on previous experiments at 23 +/- 2 degrees C, further characterization was carried out at 8 +/- 2 degrees C, 15 +/- 2 degrees C (beta-galactosidase), and 58 +/- 2 degrees C (thermostable beta-glycosidase) varying enzyme activity and flow rates. For a cost-effective process, the parameters 15 +/- 2 degrees C, 240 U/mL of beta-galactosidase, an enzyme solution flow rate of 25 L/h, and a skim milk flow rate of about 9 L/h should be used in order to achieve an aimed productivity of 360 g/(L x h) and to run at conditions for the highest process long-term stability.
authors.affiliation: Department of Medicinal Chemistry, University of Vienna, Pharmacy Centre, Althanstrasse 14, A-1090 Vienna, Austria. winfried.neuhaus@univie.ac.at
authors.forename: Winfried
authors.initials: W
authors.lastname: Neuhaus
authors.forename: Senad
authors.initials: S
authors.lastname: Novalin
authors.forename: Mario
authors.initials: M
authors.lastname: Klimacek
authors.forename: Barbara
authors.initials: B
authors.lastname: Splechtna
authors.forename: Inge
authors.initials: I
authors.lastname: Petzelbauer
authors.forename: Alexander
authors.initials: A
authors.lastname: Szivak
authors.forename: Klaus D
authors.initials: KD
authors.lastname: Kulbe
mesh_terms: D000818:Animals; D019149:Bioreactors; D001709:Biotechnology / Q000295:instrumentation / Q000379:methods; D004041:Dietary Fats / Q000302:isolation & purification; D004800:Enzymes, Immobilized; D005524:Food Technology / Q000295:instrumentation / Q000379:methods; D006868:Hydrolysis; D043322:Lactase; D007785:Lactose / Q000302:isolation & purification*; D008892:Milk / Q000737:chemistry*; D011994:Recombinant Proteins; D013696:Temperature
chemical_list: D004041:Dietary Fats; D004800:Enzymes, Immobilized; D011994:Recombinant Proteins; D043322:Lactase; D007785:Lactose