Raman Spectroscopic Determination of the Degree of Succinate in Modified Waxy Maize Starches

ABSTRACT

Waxy (essentially amylose-free) maize starch was chemically modified to varying degrees by treatment with succinic anhydride, and the degree of substitution was determined by a standard wet chemistry method. FT-Raman spectra of the modified starches were obtained, and indicated a characteristic ∼1730 cm⁻¹ C=O stretch Raman band whose intensity was dependent on the degree of succinylation. The ratio of intensity of the ∼1730 cm⁻¹ band to a ∼940 cm⁻¹ C-C stretch Raman band (used as an internal standard) was plotted against the degree of succinylation determined by titration, and a linear fit was obtained with a correlation of 0.998. Hence FT-Raman spectroscopy represents a rapid non-destructive method to determine the degree of succinylation of modified waxy maize starch, and should be suitable for use with succinylated starches of any amylose content.

Keywords::

• FT Raman spectroscopy
• succinylation
• modified starch