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

Saffron Quality 223
Figure 9. Chemical structure of mangicrocin.
acid (NAA) and kinetin (Kn). The content of the secondary metabolites in dried
stigma-like structures were considerably less than that in the intact natural stigmas
of saffron. Koyama, et al. (1988) reported on the synthesis of crocin and picrocrocin
in stigma-like and style-like tissues and its control by auxin and cytokinin.
The stigma and style portions of the plant were induced in various media. In all
cases, the HPLC analysis of the constituents of these tissues showed that they contained
crocin and other pigments equal to that of the intact stigmas. Fakhrai and
Evans (1990) supported the production of secondary products from specialised
cultured organs rather than from disorganised callus or suspended cultures to eliminate
problems of downstream processing. Still, many parameters such as frequency
of stigmas development and continuous proliferation have to be optimised. The
authors used various organs of the plant, which were incubated in basal Whites media
supplemented with many combinations of various growth regulators. All floral
parts had the potential to produce stigma-like structures depending on a critical range
of levels and a combination of growth regulators. However, it was suggested that
each explant has an inherent potential for the production of stigma-like structures.
A similar study with the above was taken on by Ebrahimzadeh, et al. (2000), who
investigated the in vitro production of stigma-like structures by various floral organs
of C. sativus. The stigma-like structures regenerated directly of indirectly through
merismatic tissues. The direct regeneration of stigma-like structures from stigma
explants was also studied by Sarma et al. (1990, 1991). Apart from producing new
tissues, the above workers proceeded with the analysis of the pigment content of
stigma-like structures. They observed that the crocin and picrocrocin contents were
lower by 8 and 6 times, respectively, than in the natural stigmas, while safranal
was not detected either in the stigma-like or in the natural stigmas. Visvanath et
al. (1990) studied first the potential of callus cultures of saffron for the production
of crocin, crocetin, picrocrocin and safranal. Callus cultures were obtained from
floral buds on Murashige and Skoog’s medium supplemented with sucrose, 2,4dichlorophenoxy
acetic acid and kinetin. The cultures led to the formation either
of red globular callous (RGC) or red filamentous structures (RFS). TLC and spectrophotometric
analysis showed that both of them contained picrocrocin at higher
concentrations than the natural stigmas, whereas their crocin content was less. The
safranal content of RGC was similar to that of the natural grown stigmas of saffron.
13-cis Crocin may be formed by photoisomerisation of crocin 1 (Speranza et al.,
1984).