Saffron is a spice derived from the flower of Crocus sativus, commonly known as the "saffron crocus". The vivid crimson stigmata and styles, called threads, are collected and dried to be used mainly as a seasoning and colouring agent in food. Saffron has long been the world's most costly spice by weight. Although some doubts remain on its origin, it is believed that saffron originated in Iran. However, Greece and Mesopotamia have also been suggested as the possible region of origin of this plant. C. sativus is possibly a triploid form of Crocus cartwrightianus. Saffron crocus slowly propagated throughout much of Eurasia and was later brought to parts of North Africa, North America, and Oceania.
Saffron's taste and iodoform- or hay-like fragrance result from the chemicals picrocrocin and safranal. It also contains a carotenoid pigment, crocin, which imparts a rich golden-yellow hue to dishes and textiles. Its recorded history is attested in a 7th-century BC Assyrian botanical treatise compiled under Ashurbanipal, and it has been traded and used for over four millennia. Iran now accounts for approximately 90% of the world production of saffron.
Description: The domesticated saffron crocus, Crocus sativus, is an autumn-flowering perennial plant unknown in the wild. It probably descends from the eastern Mediterranean autumn-flowering Crocus cartwrightianus, which is also known as "wild saffron" and originated in Crete or Central Asia. As a genetically monomorphic clone, it slowly propagated throughout much of Eurasia.
It is a sterile triploid form, which means that three homologous sets of chromosomes compose each specimen's genetic complement; C. sativus bears eight chromosomal bodies per set, making for 24 in total. Being sterile, the purple flowers of C. sativus fail to produce viable seeds; reproduction hinges on human assistance: clusters of corms, underground, bulb-like, starch-storing organs, must be dug up, divided, and replanted. A corm survives for one season, producing via this vegetative division up to ten "cormlets" that can grow into new plants in the next season. The compact corms are small, brown globules that can measure as large as 5 cm (2 in) in diameter, have a flat base, and are shrouded in a dense mat of parallel fibres; this coat is referred to as the "corm tunic". Corms also bear vertical fibres, thin and net-like, that grow up to 5 cm (2 in) above the plant's neck.
The plant sprouts 5–11 white and non-photosynthetic leaves known as cataphylls. These membrane-like structures cover and protect the crocus's 5 to 11 true leaves as they bud and develop. The latter are thin, straight, and blade-like green foliage leaves, which are 1–3 mm (0.04–0.12 in), in diameter, which either expand after the flowers have opened ("hysteranthous") or do so simultaneously with their blooming ("synanthous"). C. sativus cataphylls are suspected by some to manifest prior to blooming when the plant is irrigated relatively early in the growing season. Its floral axes, or flower-bearing structures, bear bracteoles, or specialised leaves, that sprout from the flower stems; the latter are known as pedicels. After aestivating in spring, the plant sends up its true leaves, each up to 40 cm (16 in) in length. Only in October, after most other flowering plants have released their seeds, do its brilliantly hued flowers develop; they range from a light pastel shade of lilac to a darker and more striated mauve.The flowers possess a sweet, honey-like fragrance. Upon flowering, the plants are 20–30 cm (8–12 in) in height and bear up to four flowers. A three-pronged style 25–30 mm (1.0–1.2 in) in length, emerges from each flower. Each prong terminates with a vivid crimson stigma, which are the distal end of a carpel.
Saffron contains more than 150 volatile and aroma-yielding compounds. It also has many nonvolatile active components, many of which are carotenoids, including zeaxanthin, lycopene, and various α- and β-carotenes. However, saffron's golden yellow-orange colour is primarily the result of α-crocin. This crocin is trans-crocetin di-(β-D-gentiobiosyl) ester; it bears the systematic (IUPAC) name 8,8-diapo-8,8-carotenoic acid. This means that the crocin underlying saffron's aroma is a digentiobiose ester of the carotenoid crocetin. Crocins themselves are a series of hydrophilic carotenoids that are either monoglycosyl or diglycosyl polyene esters of crocetin. Crocetin is a conjugated polyene dicarboxylic acid that is hydrophobic, and thus oil-soluble. When crocetin is esterified with two water-soluble gentiobioses, which are sugars, a product results that is itself water-soluble. The resultant α-crocin is a carotenoid pigment that may comprise more than 10% of dry saffron's mass. The two esterified gentiobioses make α-crocin ideal for colouring water-based and non-fatty foods such as rice dishes.
The bitter glucoside picrocrocin is responsible for saffron's flavour. Picrocrocin (chemical formula: C16H26O7; systematic name: 4-(β-D-glucopyranosyloxy)-2,6,6-trimethylcyclohex-1-ene-1-carboxaldehyde) is a union of an aldehyde sub-molecule known as safranal (systematic name: 2,6,6-trimethylcyclohexa-1,3-diene-1-carboxaldehyde) and a carbohydrate. It has insecticidal and pesticidal properties, and may comprise up to 4% of dry saffron. Picrocrocin is a truncated version of the carotenoid zeaxanthin that is produced via oxidative cleavage, and is the glycoside of the terpene aldehyde safranal.
When saffron is dried after its harvest, the heat, combined with enzymatic action, splits picrocrocin to yield D–glucose and a free safranal molecule. Safranal, a volatile oil, gives saffron much of its distinctive aroma.Safranal is less bitter than picrocrocin and may comprise up to 70% of dry saffron's volatile fraction in some samples. A second molecule underlying saffron's aroma is 2-hydroxy-4,4,6-trimethyl-2,5-cyclohexadien-1-one, which produces a scent described as saffron, dried hay-like.Chemists find this is the most powerful contributor to saffron's fragrance, despite its presence in a lesser quantity than safranal.Dry saffron is highly sensitive to fluctuating pH levels, and rapidly breaks down chemically in the presence of light and oxidising agents. It must, therefore, be stored away in air-tight containers to minimise contact with atmospheric oxygen. Saffron is somewhat more resistant to heat.
Saffron's aroma is often described by connoisseurs as reminiscent of metallic honey with grassy or hay-like notes, while its taste has also been noted as hay-like and sweet. Saffron also contributes a luminous yellow-orange colouring to foods. Saffron is widely used in Persian, Indian, European, and Arab cuisines. Confectioneries and liquors also often include saffron. Saffron is used in dishes ranging from the jewelled rice and khoresh of Iran, the Milanese risotto of Italy, the paella of Spain, the bouillabaisse of France, to the biryani with various meat accompaniments in South Asia. One of the most esteemed use for saffron is in the preparation of the Golden Ham, a precious dry-cured ham made with saffron from San Gimignano. Common saffron substitutes include safflower (Carthamus tinctorius, which is often sold as "Portuguese saffron" or "açafrão"), annatto, and turmeric (Curcuma longa).