Excitation wavelength selection for quantitative analysis of carotenoids in tomatoes using Raman spectroscopy

Food Chem. 2018 Aug 30:258:308-313. doi: 10.1016/j.foodchem.2018.03.089. Epub 2018 Mar 21.

Abstract

The difference in Raman spectra for different excitation wavelengths (532 nm, 785 nm, and 1064 nm) was investigated to identify an appropriate wavelength for the quantitative analysis of carotenoids in tomatoes. For the 532 nm-excited Raman spectra, the intensity of the peak assigned to the carotenoid has no correlation with carotenoid concentration, and the peak shift reflects carotenoid composition changing from lycopene to β-carotene and lutein. Thus, 532 nm-excited Raman spectra are useful for the qualitative analysis of carotenoids. For the 785 nm- and 1064 nm-excited Raman spectra, the peak intensity of the carotenoid showed good correlation with carotenoid concentration; thus, regression models for carotenoid concentration were developed using these Raman spectra and partial least squares regression. A regression model designed using the 785 nm-excited Raman spectra showed a better result than the 532 nm- and 1064 nm-excited Raman spectra. Therefore, it can be concluded that 785 nm is the most suitable excitation wavelength for the quantitative analysis of carotenoid concentration in tomatoes.

Keywords: Carotenoid (lycopene, β-carotene, lutein); Excitation wavelength; Quantitative analysis; Raman spectroscopy; Tomatoes.

MeSH terms

  • Carotenoids / analysis*
  • Least-Squares Analysis
  • Lutein / analysis
  • Solanum lycopersicum / chemistry
  • Solanum lycopersicum / metabolism
  • Spectrum Analysis, Raman / methods*
  • beta Carotene / analysis

Substances

  • beta Carotene
  • Carotenoids
  • Lutein