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Synthesis of galacto-oligosaccharides by β-galactosidase from Aspergillus oryzae using partially dissolved and supersaturated solution of lactose

Paper ID Volume ID Publish Year Pages File Format Full-Text
17381 42664 2012 7 PDF Available
Title
Synthesis of galacto-oligosaccharides by β-galactosidase from Aspergillus oryzae using partially dissolved and supersaturated solution of lactose
Abstract

The effect of enzyme to substrate ratio, initial lactose concentration and temperature has been studied for the kinetically controlled reaction of lactose transgalactosylation with Aspergillus oryzae β-galactosidase, to produce prebiotic galacto-oligosaccharides (GOS). Enzyme to substrate ratio had no significant effect on maximum yield and specific productivity. Galacto-oligosaccharide syntheses at very high lactose concentrations (40, 50 and 60%, w/w, lactose monohydrate) were evaluated at different temperatures (40, 47.5 and 55 °C). Within these ranges, lactose could be found as a supersaturated solution or a heterogeneous system with precipitated lactose, resulting in significant effect on GOS synthesis. An increase in initial lactose concentration produced a slight increase in maximum yield as long as lactose remained dissolved. Increase in temperature produced a slight decrease in maximum yield and an increase in specific productivity when supersaturation of lactose occurred during reaction. Highest yield of 29 g GOS/100 g lactose added was obtained at a lactose monohydrate initial concentration of 50% (w/w) and 47.5 °C. Highest specific productivity of 0.38 g GOS h−1 mg enzyme−1 was obtained at lactose monohydrate initial concentration of 40% (w/w) and 55 °C, where a maximum yield of 27 g GOS/100 g lactose added was reached. This reflects the complex interplay between temperature and initial lactose concentration on the reaction of synthesis. When lactose precipitation occurred, values of yields and specific productivities lower than 22 g GOS/100 g lactose added and 0.03 g GOS h−1 mg enzyme−1were obtained, respectively.

► Enzymatic synthesis of galacto-oligosaccharides was studied at high lactose concentrations. ► Higher yields and productivities were obtained under substrate supersaturation. ► Enzyme to substrate ratio had no significant effect on yield and specific productivity. ► Effect of temperature on yield varied according to the physical state of the substrate. ► At partially dissolved lactose, soluble lactose and GOS yield increased with temperature.

Keywords
Galacto-oligosaccharides; β-Galactosidase; Aspergillus oryzae; Prebiotic
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Synthesis of galacto-oligosaccharides by β-galactosidase from Aspergillus oryzae using partially dissolved and supersaturated solution of lactose
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Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 50, Issue 3, 10 March 2012, Pages 188–194
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us