Discrimination of irradiated starch gels using FT-raman spectroscopy and chemometrics

The effects of γ-irradiation on starch gels were characterized at the molecular level by Fourier transform (FT) Raman spectroscopy. Starches from five different sources were gelatinized and irradiated at 3, 5, and 10 kGy using a Co⁶⁰ γ-irradiator. γ-irradiation effects on starch gels were noted by the C-H stretch (2800-3000 cm^-1) and O-H stretch (3000-3600 cm^-1) and bend (1600-1800 cm^-1) regions of the FT-Raman spectra. FT-Raman molecular fingerprints obtained through spectral analyses were used for discrimination of the gels based on the extent of irradiation by means of two different pattern-recognition techniques: canonical variate analysis (CVA) and soft modeling of class analogy (SIMCA). A complete discrimination of irradiated starches was attained using a hybrid partial least-squares (PLS) and CVA model, using the spectral variations in the C-H stretch and O-H stretch and bend regions of FT-Raman spectra. Using the same spectral regions, SIMCA predicted 84% of samples correctly.