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.

Effects of mild temperature conditions during dehydration procedures on saffron quality parameters.

BACKGROUND: The dehydration procedure is responsible for saffron sensorial properties: colour, taste and aroma. Changes in the compounds responsible for these characteristics have been studied when dehydration processes at high and low temperature are employed. However, the evolution of these changes at mild temperatures is not available in the current bibliography. In this paper the effect of different mild conditions (18-20 degrees C for 24 h, 40-50 degrees C for 75 min and 55 degrees C for 75 min) applied to 45 saffron samples with the same origin was investigated. RESULTS: Crocetin esters, the compounds responsible for saffron colour, increased their content with no significant differences from other processes when high temperatures (55 degrees C) were used, thus producing a noticeable increment in saffron colouring capability. Similar behaviour was obtained for picrocrocin, the compound responsible for saffron taste, with higher average content at the highest temperature (55 degrees C) but without significant differences with the inferior conditions (40-50 degrees C). However, more volatile compounds were generated, especially safranal,at higher temperatures, e.g. 55 degrees C, during the dehydration procedure. CONCLUSIONS: The results found support the idea for employing mild to high temperatures during the dehydration process of saffron.

Picrocrocin content and quality categories in different (345) worldwide samples of saffron ( Crocus sativus L.).

In this paper, 345 saffron samples were analyzed from different countries to study their picrocrocin content using different analytical techniques. The E1cm 1% of 257 nm results from all samples are inflated in comparison by the high-performance liquid chromatography (HPLC) data, because of the interferences with the crocetin ester pool and especially with those with a lower trans/cis relation. A picrocrocin range update is proposed for International Organization for Standardization (ISO) 3632 normative because category III should be incremented up to 50 units, while category II should be incremented up to 60 units. More accurate data are achieved when the deltaEpic measurement is carried out. Consequently, improvements to the ISO method are suggested. Fourier transform (FT)-near-infrared spectrometry analysis has also been carried out, showing excellent results from the calibration with HPLC data. This spectrophotometric technique could be used by saffron enterprises to obtain quick and more accurate data for picrocrocin determination.