What is saffron, and what gives it colour and aroma?

Saffron is a spice made from the dried red stigmas of the Crocus sativus flower. Its yellow-red colour comes from crocins, water-soluble carotenoid pigments; its bitter taste comes from picrocrocin; and its aroma comes mainly from safranal. It is one of the most expensive spices in the world because each flower gives only three thin threads, picked and separated by hand: one kilogram of dry saffron takes 110,000 to 165,000 flowers. Saffron is a spice, not a nutrient, so it has no Thai Reference Daily Intake (Thai RDI).

In short:

• What it is: the dried stigmas of Crocus sativus, a plant of the iris family
• Colour: crocins (yellow-red, dissolve in water)
• Taste: picrocrocin (bitter)
• Aroma: safranal, formed from picrocrocin during drying and storage
• Quality grades: ISO 3632, Categories I, II and III
• Adulteration: safflower, marigold, turmeric and synthetic dyes have been found mixed in
• Thai RDI: none

In Thai, saffron is called หญ้าฝรั่น. It is a different plant from turmeric (ขมิ้นชัน) and safflower (ดอกคำฝอย), even though all three are used to colour food yellow. For turmeric, see What are turmeric and curcumin, and how much is in food?

What is saffron?

Which plant does it come from?

A 2022 review in the journal Foods, by researchers at the Benemérita Universidad Autónoma de Puebla and the Universidad Autónoma de Chihuahua in Mexico, describes saffron as the commercial name for the dried red stigmas of the Crocus sativus flower. The stigma is the top of the flower's female part (the pistil). In this plant, a thin white style ends in a stigma divided into three threads, and the stigma makes up only about 7 to 7.4% of the flower.

Crocus sativus belongs to the iris family (Iridaceae). The review says the plant is sterile, so it cannot be grown from seed and must be propagated by planting corms, the bulb-like underground stems, by hand. It is grown in Iran, Spain, India and Greece, and the review names Iran and Spain as the principal producers.

Why is saffron so expensive?

Almost every step is done by hand. The same review says that one kilogram of dry saffron requires 110,000 to 165,000 flowers, which means about 50 hours of work to pick the flowers and another 200 hours to separate the stigmas from them. After that, the stigmas are sorted, dried and stored.

What gives saffron its colour, taste and aroma?

Three groups of compounds

Saffron's character comes mainly from compounds formed from carotenoids. The 2022 review gives these ranges for saffron, which vary with origin, harvest and handling:

Crocins and crocetin

Crocins are carotenoids bound to sugars, which is why they dissolve in water. In the US chemical database PubChem, crocin has the formula C44H64O24. Crocetin is the part of crocin left when the sugars are removed; the review describes it as fat-soluble.

Picrocrocin and safranal

Picrocrocin is the source of saffron's bitterness. The review explains that during drying and storage, picrocrocin loses its sugar and forms safranal, the main aroma compound. So the bitter compound and the aroma compound are linked: one is made from the other.

What else does saffron contain?

Saffron also contains ordinary nutrients. The figures below are per 100 g of dried saffron from the US Department of Agriculture's FoodData Central database. They describe the spice itself; a dish uses only a few threads, far less than 100 g.

How is saffron quality graded?

The ISO 3632 categories

The international standard ISO 3632 grades saffron by measuring how strongly a water extract absorbs light at three wavelengths: 440 nm for colouring strength (crocins), 257 nm for flavour strength (picrocrocin) and 330 nm for aroma strength (safranal). The 2022 review lists these limits:

What studies of real samples found

A 2025 study from the University of Milan analysed 125 saffron samples from Italian regions harvested in 2021 and 2022, and found that 95% met Category I. The authors proposed splitting Category I into three subcategories. The samples came from one country and two seasons.

A 2010 study led by the University of Castilla-La Mancha in Spain analysed 345 samples from different countries. It found that the light-absorption reading for picrocrocin was inflated compared with liquid chromatography (HPLC), because the crocins, saffron's own colour compounds, also absorb at that wavelength, and proposed updating the picrocrocin ranges in ISO 3632.

How do drying and storage change saffron?

Drying

The 2022 review describes two approaches to drying the stigmas: room or moderate temperatures of 35–45 °C for a long time, or very short drying at 60–70 °C. The drying method affects colour, compounds, flavour and aroma.

Storage

The review says colour intensity decreases by nearly 30 to 40 units per year. A 2018 study from the University of Tehran compared freshly dried saffron with saffron stored for two years. The freshly dried samples had more crocins and picrocrocin, while the stored samples had more safranal. The researchers concluded that during storage the colour decreases while the aroma increases. The study used Iranian samples and spectrophotometric and gas chromatography methods.

How is saffron used in food?

The 2022 review names dishes in which saffron is traditional: paella in Spain, Milanese risotto in Italy, lussekatter buns in Sweden, and some alcoholic beverages.

Saffron is also used as a food colour. Under US federal regulation 21 CFR 73.500, the colour additive saffron is defined as the dried stigma of Crocus sativus and may be used for colouring foods generally, in amounts consistent with good manufacturing practice, and batches are exempt from certification.

How is saffron different from safflower and turmeric?

Three different plants

Mixing and substitution

Because saffron is expensive, cheaper materials are sometimes mixed in or sold in its place. A systematic review published online in 2025 of 23 studies published from 2015 to 2025, by researchers in Iran, India and Pakistan, estimated that 20 to 30% of commercial saffron is adulterated, with large regional differences: 3.5% in regulated EU markets compared with 60% in India. Common practices were substitution with safflower, marigold or turmeric, dilution with other plant material, and the addition of synthetic dyes such as Sudan dyes and auramine O. The figures pool studies with different methods and markets.

A 2011 study by the Italian agriculture ministry's food fraud laboratory in Catania added safflower, marigold and turmeric to saffron. The ISO light-absorption test could not detect additions of up to 10 to 20% by weight; with 20 to 50%, the saffron was placed in the wrong category. Liquid chromatography with mass spectrometry identified marker molecules at 5% for safflower and marigold and 2% for turmeric. A study from Ibn Zohr University published online in 2025 in Morocco developed a DNA test that detects safflower, turmeric and maize (corn) in saffron in a single reaction.

Is there a recommended daily amount of saffron?

No. Saffron is a spice, not a nutrient, so it has no Thai Reference Daily Intake (Thai RDI). The figures in this article describe what saffron contains and how it is graded, not how much anyone needs.

In the United States, saffron appears in the list under 21 CFR 182.10 of spices and natural seasonings that are GRAS (generally recognized as safe) for their intended use. This listing covers use as a spice; use as a food colour is covered separately under 21 CFR 73.500. It is not a recommended amount, and it is not an assessment of saffron extracts taken as supplements.

Who should be careful with saffron?

People with allergies

A 1997 study from the Hospital Complex of Ciudad Real in Spain examined 50 saffron workers. Three were sensitised to proteins from saffron pollen and stamens, and among 237 people with allergies from the general population, 10 also tested positive to saffron. The researchers did not find allergenic components in the pistils, the part that includes the stigma, and they found cross-reactivity with some other pollens. The study looked at people handling the flowers at work. Anyone who has reacted to saffron or to plant pollen should ask a doctor before eating it.

People taking saffron as a supplement or extract

Saffron extracts in supplements are a different form from the few threads used in cooking. If you use one, tell your doctor or pharmacist about it and about any other supplements and medicines you take.

Pregnant or breastfeeding women and people who take regular medication

If you are pregnant or breastfeeding, or take medication regularly, check with a doctor or pharmacist before taking supplements.

Dietary supplements are not intended to prevent, treat or cure any disease.