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General Application of Raman Spectroscopy for the Determination of Level of Acetylation in Modified Starches¹

¹Presented at the AACC 83rd Annual Meeting, Minneapolis, MN, September 1998. ²Dept. of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong. ³Dept. of Botany, The University of Hong Kong, Pokfulam Road, Hong Kong. ⁴Corresponding author: E-mail: hcorke@yahoo.com Fax: +852 2858 3477.

A method using Raman spectroscopy was recently developed for the determination of the degree of acetylation in modified wheat starch. In this article, we show that the method can be generalized to a wide range of starches of different botanical origin and amylose content. Calibration sets were used to develop regression equations for 11 types of acetylated starches, including cereal (rice, maize, wheat) and noncereal (potato and sweetpotato) sources. The calibration lines were then used to predict the level of acetylation of starch samples with unknown level of acetylation using their Raman spectra. In each case, R² > 0.98 for linear regression of Raman vs. titrimetric determination of acetylation. The Raman-based calibration curves allow fast and nondestructive determination of the degree of acetylation for different types of starches.