Saffron types are graded by quality according to laboratory measurements
of such characteristics as crocin (colour), picrocrocin (taste), and
safranal (fragrance) content. Other metrics include floral
waste content (i.e. the saffron spice sample's non-stigma
floral content) and measurements of other extraneous matter
such as inorganic material ("ash"). A uniform set of
international standards in saffron grading was established by the
International Standards Organization, which is an international
federation of national standards bodies. Namely, ISO 3632 deals
exclusively with saffron. It establishes four empirical grades
of colour intensity: IV (poorest), III, II, and I (finest
quality). These are determined by finding the spice's crocin
content.
Minimum saffron colour grading standards (ISO 3632) ISO Grade Crocin-specific absorbance (Aλ) score (at λ=440 nm)
Category I > 190 Category II 150–190 Category III 110–150 Category IV 80–110
