Effect of pH and Laccase Enzyme Concentration on the Properties of Syringaldehyde

Nor Syuhada Mohd Sham; Mohamad Yusof Maskat

Abstract

Effect of pH and Laccase Enzyme Concentration on the Properties of Syringaldehyde

Author(s): Nor Syuhada Mohd Sham, Mohamad Yusof Maskat

Syringaldehyde is recognized as a main component of monolignol in oil palm empty fruit bunch. The structure of syringaldehyde comprised of two methoxy groups, which have the potential to undergo demethoxylation process. Laccase enzyme from Trametes versicolor species have been reported to be able to demethoxylate at certain pH. Hence, the objective of this study is to characterize the effect of laccase enzyme concentration and pH of acetate buffer on syringaldehyde compound. Nine syringaldehyde preparation based on different pH and percentage of laccase enzyme treatment were studied. Phenolic acid and aldehyde compound were determined using HPLC and characterizations of the treated syringaldehyde were done using NMR. Based on HPLC results, no targeted compound of 4-hydroxybenzoic, vanillic, syringic, p-coumaric, trans-ferulic, 4-hydroxybenaldehyde, vanillin and guaiacyl were detected. However there was an uknown compound was detected for some of the sample. Concentration of syringaldehyde was found to be decreasing with increase of enzyme percentage starting from pH 4 and 5. A change of the carbonyl group was detected based on the presence of peaks at about 1.89 ppm using 1H NMR and 173.33 ppm using 13C NMR. The absence of methoxy groups in combination of pH 5 and 5% laccase enzyme sample were detected on 13C NMR spectrum prove that this treatment appeared to give maximum changes in functional group compared to the other samples.

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