Electrochemical Studies Of Hydrolytic Products From Refined Palm Oil With Immobilized Enzymes At Modified Carbon Electrodes
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Date
2012-07
Authors
Jarjes, Zahraa A.
Journal Title
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Publisher
Universiti Sains Malaysia
Abstract
This work describes the effect of pH, temperature, incubation time, and substrate and enzyme weights on the hydrolysis of refined palm oil using the commercial lipase from the yeast Candida rugosa. It was found that the hydrolysis was optimum at pH 7.5, temperature 37 °C, incubation time 60 min and the enzyme and substrate weights of 0.1 and 2 g, respectively. The released fatty acids were used as a substrate for lipoxygenase immobilized on modified Nafion membrane carbon electrode and the current generated was studied by cyclic voltammetry. Potassium buffer at pH 7 and 0.4 mg of lipoxygenase was found to be crucial in order to produce a higher current density.
The electrooxidation of glycerol (obtained at optimum conditions of hydrolysis of refined palm oil using commercial lipase) in the presence of nicotinamide adenine dinucleotide (NAD+) using glycerol dehydrogenase enzyme immobilized in ammonium modified Nafion membrane on polymer modified carbon cloth electrodes. Due to the large overvoltage encountered for NADH oxidation at the electrode, five conducting polymers viz. polymethylene green (PMG), polyaniline (PANI), poly(ortho-phenylene diamine) (PoPD), poly(4-vinyl pyridine) (P4VP), and polypyrrole (PPy) were used to regenerate NAD+ and to shuttle electrons from the NADH to the electrode. In general, the redox processes of glycerol were of quasi-reversible over potential ranges of -0.5 to
+0.6 V vs Ag/AgCl. The effect of pH, concentrations of NAD+, and weight of lipase has been studied to achieve a higher current density.
Description
Keywords
Hydrolytic products from refined palm oil with , immobilized enzymes at modified carbon electrodes