Production Practices and Quality Assessment of Food Crops. Vol. 1

(1984) gives the following data: δ 7.35 (2H, d, J = 11.4), δ 6.66 (2H, dd, J = 11.4,
15.0), δ 6.82 (2H, d, J = 15.0), δ 6.53 (2H, dd, J = 8.0, 2.5), δ 6.86 (2H, dd, J =
8.0, 2.5), δ 1.97 (2H, s), δ 2.00 (2H, s), δ 5.42 (1H, d, J = 7.5), δ (1H, dd, J =
7.5, 7.5), δ 3.0–3.3 (7H, m), δ 3.4–4.0 (2H, m).
2.5.2. Picrocrocin
According to Tarantilis et al. (1994b), the isolation of picrocrocin is achieved
initially by successive extraction of saffron components in a Soxhlet apparatus
with light petroleum, diethyl ether and methanol. Picrocrocin, which was present
in the diethyl ether extract, was purified in the Soxhlet extractor, diluted with
methanol and passed through a 0.45 µ filter. Finally, it was analysed by HPLC
using three different conditions (see Table 3) and detected by UV-Vis. Except for
its absorption maxima at 250 nm (broad band due to the α, β-unsaturated cycloaldehyde
moiety), picrocrocin also exhibited a shoulder at 350 nm. Himeno and Sano
(1987) reported the in vitro synthesis of picrocrocin in stigma like structures of
saffron. The main analytical methods that have been applied to the analysis of picrocrocin
include thin layer chromatography (Iborra et al., 1992b; Sujata et al., 1992)
and HPLC (Sujata et al., 1992; Tarantilis et al. 1995; Alonso et al., 2001). Different
investigators give spectroscopic characteristics of picrocrocin. Iborra et al. (1992b)
referred to the IR spectrum of an aqueous solution of picrocrocin in caesium chloride
plates: 3400, 2950, 1620, 1410, 1360, 1080 and 1040 cm –1 in deutered water and
1410, 1350, 1075 and 1035 cm –1 in water. The latter also reported 1 H-NMR and
13 C-NMR spectra of this compound.
2.5.3. Volatiles
Saffron Quality 225
The common extraction processes for the volatile components of saffron are steam
distillation (SD), solvent (hydrophilic to hydrophobic), vacuum headspace (VHS) or
dynamic headspace (DHS) extraction. Tarantilis and Polissiou (1997) have examined
the effects of the extraction method on the composition of the obtained essential
oil. After identification of the volatile compounds with GC-MS analysis, they came
to the conclusion that the higher the temperature of the extraction, the more drastic
the changes in the structure and the nature of the ingredients of each volatile fraction.
Apart from this, Loskutov et al. (2000) showed that safranal as being water-insoluble,
is better extracted with hydrophobic solvents while its concentration in the
extracts remains stable with time. However, such methods for extracting volatile
components are highly destructive for the sample. A non-destructive technique for
the isolation of safranal and oxysafranal (HTCC) from the solid matrix has been
proposed by Semiond et al. (1996) and Lozano et al. (2000). It refers to the application
of a supercritical fluid (CO 2) to the extraction of the above volatile oils directly
from saffron powder within a short time.
Several methods have been proposed for the qualitative and quantitative analysis
of the aroma compounds of saffron. Estimation of safranal content can be achieved
by measuring the absorbance at 330 nm (ISO 3632, 1993) of an aqueous extract
of saffron or by chromatographic methods. The spectrophotometric estimation is not