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

Saffron Quality 231
Saffron in filaments (or threads) or in powder form should be packed in containers
that do not affect the content. Commercial and botanical names, name and
address of the producer or packer, trade mark, batch or code number, commercial
category and other information required by the client (harvest year, packing date
etc) are required on labelling.
According to the Part 2 of the above standard the test methods and the analytical
procedures are described in details. To spare saffron sample (2 × 5 g) provision
for the exact order of test procedures is necessary for repeating certain analyses
in the case of disputes. In the 1975 edition of ISO standard a dichromate number
that is, the concentration of a K 2Cr 2O 7 solution that gives the same colour intensity
as a 0.01% saffron solution, was included (Corradi and Michelli, 1979b).
Identification tests include reaction with sulfuric acid and diphenylamine and thin
layer chromatography. There are underway collaborative trials of an ISO task force
for the development and standardisation of TLC and HPLC procedures for the
detection of artificial water-soluble colourings (Saltron et al., 1999). The use of
instrumental analytical procedures for grading saffron is gaining interest (Curro et
al., 1986; Solinas and Cichelli, 1988; Sujata et al., 1992).
Microscopic observation of typical anatomical elements is valuable to test the
authenticity of powdered saffron in a) distilled water, b) in sodium or potassium
hydroxide solution and c) in aqueous iodine/iodide solution. The alkali treatment
destroys the greatest part of the starch and also the cellular elements (sclerous
elements, vessels, fibres and epidermis) become easier to observe. On the other hand
the starch grains are stained blackish blue or violet with iodine/iodide solution.
Among the diagnostic characters of at most importance are the upper epidermis
of the stigmas with small papillose protuberances and the large pollen grains.
The determination of the major organoleptic characteristics of saffron (picrocrocin,
safranal and crocins) is carried out in an oversimplified way by spectrometric
evaluation of an aqueous extract at three characteristic maxima 257, 330 and
440 nm, respectively. The drawbacks of the procedure have been often criticised
by many investigators (e.g., Amelotti and Mannino, 1977; Basker and Negbi, 1985;
Figure 10. Anatomical structure of powdered saffron (After ISO standard 3632-2/1993).