title: Characterization of β-glucosidase immobilized on chitosan-multiwalled carbon nanotubes (MWCNTS) and their application on tea extracts for aroma enhancement.
abstract: β-Glucosidase was covalently immobilized on chitosan-MWCNTs carrier and its aroma enhancement effect in different tea samples was investigated. Chitosan-MWCNTs carrier was prepared by mixing chitosan with MWCNTs (5:1w/w) and characterization of prepared composite carrier was done by FTIR, TGA and SEM analysis. β-Glucosidase was covalently immobilized on the composite carrier after glutaraldeyde activation. After optimization of the immobilization conditions, immobilization yield was achieved as 95.22%. Optimum pH was found as pH 6.0 and pH 5.0 for free and immobilized enzyme, respectively. Optimum temperature of the enzyme was shifted from 35°C to 45°C after immobilization. The Km and Vmax values for immobilized β-glucosidase calculated as 5.55mM and 7.14U/mg protein respectively. Immobilized β-glucosidase showed better pH and storage stability than free enzyme. After storage at +4°C for 50days, the immobilized enzyme retained its 68.4% of the initial activity. The calculated half-life (t1/2) of immobilized enzyme was 115.8min. After 10 cycles of reuse, immobilized β-glucosidase showed 72.83% of its initial activity.
authors.affiliation: Celal Bayar University, Faculty of Science and Arts, Chemistry Department,45140, Muradiye, Manisa, Turkey. Electronic address: akile-celik@hotmail.com.
authors.forename: Akile
authors.initials: A
authors.lastname: Çelik
authors.affiliation: Celal Bayar University, Faculty of Science and Arts, Chemistry Department,45140, Muradiye, Manisa, Turkey. Electronic address: ayse.dincer@cbu.edu.tr.
authors.forename: Ayşe
authors.initials: A
authors.lastname: Dinçer
authors.affiliation: Celal Bayar University, Faculty of Science and Arts, Chemistry Department,45140, Muradiye, Manisa, Turkey. Electronic address: aydemirt@yahoo.com.
authors.forename: Tülin
authors.initials: T
authors.lastname: Aydemir
mesh_terms: D048271:Chitosan / Q000737:chemistry; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry*; D005511:Food Handling; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D037742:Nanotubes, Carbon / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013662:Tea / Q000737:chemistry / Q000145:classification*; D013696:Temperature; D001617:beta-Glucosidase / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D037742:Nanotubes, Carbon; D013662:Tea; D048271:Chitosan; D001617:beta-Glucosidase
keywords: Aroma-increasing effect; Chitosan; Immobilization; MWCNTs; β-Glucosidase