Stigma (saffron)

Each saffron flower has six tepals, three stamens and a white style that ends in a stigma split into three threads [1]. While growing, the stigmas change color from white to intense red [1]. They are the one marketable part of the plant; the rest is called the floral biomass [2]. US regulations use the same definition: the color additive saffron is the dried stigma of Crocus sativus L. [5].

The stigmas contain a rich array of bioactive compounds, notably crocin, crocetin, picrocrocin and safranal [1]. Safranal is not present in fresh stigmas, so its amount in the finished spice depends heavily on drying and storage [1].

Saffron studies do not all give the same thing. A 2026 systematic review of saffron safety named the wide heterogeneity in product type (stigma powder versus extract), standardization method and reporting of active compounds as the main obstacle to comparing studies [3]. When reading a saffron trial, look for whether it used ground stigma or an extract, and which compounds the extract was standardized to.

Product identity is a second issue. Because saffron is expensive, economically motivated adulteration occurs relatively often [4]. A laboratory study of saffron powder screened for botanical adulterants including safflower, calendula and turmeric [4]. A trial or product that documents the source and testing of its saffron is easier to interpret than one that does not.

For the graded evidence, see Saffron.

• Standardized extract
• Botanical extract
• Certificate of analysis
• Rhizome