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

and Micheli, 1979; Curro et al., 1986; Roedel and Petrzika, 1991; Tarantilis et al.,
1997; Straubinger et al., 1998) though even lower levels have been reported
(ca. 30%) (Zareena et al., 2001). Some minor volatile compounds are believed to
derive from non-volatile precursors such as carotenoids, when the latter are exposed
to heat, light, oxygen or activity of β-glucosidase (Tarantilis et al., 1995; Raina et
al., 1996; Straubinger et al., 1997; Straubinger et al., 1998). The presence of such
compounds may affect negatively the aroma of saffron.
2.5. Isolation, synthesis and analysis of crocins, picrocrocin and volatiles
Several solvents have been used in order to extract the saffron constituents.
Methanol-water (Koyama et al., 1988; Tarantilis et al., 1995; Orfanou and Tsimidou,
1996; Straubinger et al., 1997; Lozano et al., 1999; Soeda et al., 2001), ethanolwater
(Buchecker and Eugster, 1973; Pfander and Wittwer, 1975; Speranza et al.,
1984; Gómez et al., 1987b; Himeno and Sano, 1987; Visvanath et al., 1990;
Oberdieck et al., 1991; Sujata et al., 1992; Loskutov et al., 2000) diethyl ether
(Zarghami and Heinz, 1971; Pfander and Schurtenberger, 1982; Tarantilis and
Polissiou, 1997; Zareena et al., 2001) petroleum ether (Tarantilis et al., 1994b) or
aqueous extracts of saffron (Basker and Negbi, 1985; Alonso et al., 1990; Iborra
et al., 1992a; Iborra et al., 1992b; Orfanou and Tsimidou, 1996; Tsimidou and
Billiaderis, 1997; Selim et al., 2000) have been used. Among these, water was found
to be the solvent of choice in the case of crocins, and picrocrocin extraction whereas
safranal and HTCC were better extracted with less polar solvents.
2.5.1. Crocins
Saffron Quality 221
Isolation procedures for crocin 1 or for crocins have been developed by many investigators
(Weber and Grosch, 1976; Speranza et al., 1984; Iborra et al., 1992; Pfister
et al., 1996; Soeda et al., 2001; Zareena et al., 2001; Zhang et al., 2001). Isolation
procedures for crocins from gardenia seeds have also been reported by Pfister et
al. (1996), Van Calsteren et al. (1997) and Pham et al. (2000). Some useful protocols
are given in Table 2.
Detailed chromatographic and spectroscopic analysis in the work of Straubinger
et al. (1997) indicated the presence of the following glucosides: paracetylated
digentiobiosyl ester of crocetin (fraction I), paracetylated β-D-gentiobiosylβ-D-glucopyranosyl
ester of crocetin, (2E,4E)-2-methyl-6-oxohepta-2,4-dienoic acid
β-D-gentiobiosyl ester, 3,5,5-trimethyl-cyclohexenone derivatives (fraction II) and
(4S)-4-(hydroxymethyl)-3,5,5-trimethylcyclohex-2-enone-β-D-glucopyranoside
(fraction III).
A novel xanthone-carotenoid glycoside, mangicrocin (C 45H 50O 19) has been isolated
by Ghosal et al. (1989) as an optically active, yellowish-brown amorphous powder.
The compound was extracted from homogenised stigmas of saffron using a mixture
of solvents (Et 2O, EtOAc, BuOH), analysed with column chromatography and
TLC and finally, identified by its MS and NMR spectra. Its chemical structure is
given in Figure 9.
Synthesis of crocins depends heavily on biotechnology (e.g., Himeno and Sano,