Quantification of crocetin esters in saffron (Crocus sativus L.) using Raman spectroscopy and chemometrics.
The feasibility of Raman spectroscopy for predicting the content of crocetin esters (crocins), and coloring strength was assessed. 114 samples from Greece, Iran, Italy and Spain were divided into two sets: a calibration set with 49 samples and a validation one with 65 samples. Calibration models for crocetin esters (r 0.97, RMSEC 0.92, RMSEP 0.97, RPD 3.46) and coloring strength (r 0.95, RMSEC 12.2, RMSEP 11.3, RPD 2.59) were built in the spectral region 1700-955 cm(-1) using partial least-squares (PLS) regression. The calibration models were validated using cross-validation, leaving one sample out (r 0.97, RMSECV 1.09 for crocetin esters and r 0.93, RMSECV 14.5 for coloring strength). The crocetin esters content as determined by liquid chromatography fluctuated between 18.8 and 31.7 mg/100 g saffron. The corresponding values, as calculated using the Raman method, fluctuated between 19.2 and 32.0 mg/100 g saffron. The coloring strength determined by the reference method ranged from 177.0 to 296.7 units, while with the Raman method the values were between 186.8 and 297.6 units. The results, as compared to the reference methods (liquid chromatography and UV-vis spectrophotometry), show that the proposed methodology gives data with acceptable accuracy. The proposed models can be used as a tool for rapid screening of quality in saffron samples.
Anastasaki
Eirini G
EG
Laboratory of Chemistry, Department of Science, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece.
Kanakis
Charalabos D
CD
Pappas
Christos
C
Maggi
Luana
L
Zalacain
Amaya
A
Carmona
Manuel
M
Alonso
Gonzalo L
GL
Polissiou
Moschos G
MG
D002138:Calibration; D002338:Carotenoids / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D003116:Color; D027622:Crocus / Q000737:chemistry*; D004952:Esters / Q000032:analysis*; D016018:Least-Squares Analysis; D011786:Quality Control; D015203:Reproducibility of Results; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014801:Vitamin A / Q000031:analogs & derivatives
D004952:Esters; C487773:trans-sodium crocetinate; D014801:Vitamin A; D002338:Carotenoids; C029036:crocin