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Quantitative Analysis of Benzyl Modification in Waxy Maize Starch by Fourier Transform (FT) Raman Spectroscopy

¹Dept. of Chemistry; The University of Hong Kong, Pokfulam Road, Hong Kong. ²Corresponding authors. E-mail: phillips@hku.hk and harold@hku.hk Fax: +852 2858-3477. ³Department of Botany, The University of Hong Kong.

Waxy maize starch was chemically modified to varying benzylation levels and the degree of benzylation substitution was measured using a nuclear magnetic resonance (NMR) method. Fourier Transform (FT) Raman spectra of the chemically modified starches were acquired and aromatic C=C stretch Raman bands characteristic of the benzylation modification were used to derive a calibration curve for the Raman intensity of these marker bands versus the degree of benzylation substitution. The best-fit linear regression to the plotted data gave a linear correlation coefficient of 0.997. The FT-Raman technique provides a fast, nondestructive method for the measurement of the degree of benzylation substitution of modified waxy maize starches and should be applicable for use with benzylated starches from other botanical sources.