Chitosan-immobilized pectinolytics with novel catalytic features and fruit juice clarification potentialities

Muhammad Irshad; Aimen Murtza; Muddassar Zafar; Khizar Hayat Bhatti; Abdul Rehman; Zahid Anwar

doi:10.1016/j.ijbiomac.2017.06.027

Chitosan-immobilized pectinolytics with novel catalytic features and fruit juice clarification potentialities

Int J Biol Macromol. 2017 Nov;104(Pt A):242-250. doi: 10.1016/j.ijbiomac.2017.06.027. Epub 2017 Jun 7.

Authors

Muhammad Irshad¹, Aimen Murtza², Muddassar Zafar², Khizar Hayat Bhatti³, Abdul Rehman⁴, Zahid Anwar²

Affiliations

¹ Department of Biochemistry and Biotechnology, University of Gujrat, Pakistan. Electronic address: mirshad.uog@gmail.com.
² Department of Biochemistry and Biotechnology, University of Gujrat, Pakistan.
³ Department of Botany, University of Gujrat, Pakistan.
⁴ Biochemistry and Biotechnology, Baghdad-ul-Jadeed Campus, The Islamia University Bahawalpur, Pakistan.

PMID: 28600206
DOI: 10.1016/j.ijbiomac.2017.06.027

Abstract

Biological macromolecules are primarily composed of complex polysaccharides that strengthen microbial growth for the production of industrially relevant enzymes. The presence of polysaccharides in the form of the disrupted cell wall and cell materials are among major challenges in the fruit juice industry. The breakdown of such biological macromolecules including cellulose and pectin is vital for the juices processing. In this background, pectinolytic enzymes including polygalacturonase (PG), pectin lyase (PL), and pectin methylesterase (PME) were isolated from Aspergillus ornatus, statistically optimized and purified via ammonium sulfate fractionation (ASF), dialysis, and Sephadex G-100 gel permeation chromatography. After passing through Sephadex G-100 column, PG, PL, and PME were 2.60-fold, 3.30-fold, and 4.52-fold purified with specific activities of 475.2U/mg, 557.1U/mg, and 205.7U/mg. The active PG, PL, and PME, each separately, were surface immobilized using various concentrations of chitosan and dextran polyaldehyde as a macromolecular crosslinking agent. Prior to exploit for juice clarification purposes, various parameters including pH, thermal and Michaelis-Menten kinetic constants of purified and chitosan-immobilized fractions were investigated. A considerable improvement in the pH and thermal profiles was recorded after immobilization. However, the negligible difference between the K_m and V_max values of purified free and chitosan-immobilized fractions revealed that the conformational flexibility of pectinolytics was retained as such. A significant color and turbidity reductions were recorded after 60min treatment with CTS-PG, followed by CTS-PME, and CTS-PL. It can be concluded that the clarification of apples, mango, peach, and apricot juices was greatly affected by CTS-PG, CTS-PME, and CTS-PL treatments rendering them as potential candidatures for food industry applications.

Keywords: Applications; Aspergillus ornatus; Biological macromolecules; Chitosan; Enzymatic catalysis; Immobilization; Pectinolytic.

MeSH terms

Aspergillus / enzymology
Chitosan / chemistry*
Enzymes, Immobilized / chemistry*
Enzymes, Immobilized / metabolism*
Fruit and Vegetable Juices*
Hydrogen-Ion Concentration
Hydrolysis
Kinetics
Pectins / chemistry*

Substances

Enzymes, Immobilized
Pectins
Chitosan