saffron

Saffron crocus
C. sativus flower with red stigmas
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
Order:	Asparagales
Family:	Iridaceae
Subfamily:	Crocoideae
Genus:	Crocus
Species:	C. sativus
Binomial name
Crocus sativus L.

Saffron (IPA: [ˈsæf.ɹən] / [ˈsæf.ɹɒn]) is a spice derived from the flower of the saffron crocus (Crocus sativus), a species of crocus in the family Iridaceae. A C. sativus flower bears three stigmas, each the distal end of a carpel. Together with their styles—stalks connecting stigmas to their host plant—stigmas are dried and used in cooking as a seasoning and colouring agent. Saffron, for decades the world's most expensive spice by weight,^[1][2] is native to Southwest Asia.^[2][3]

Saffron is marked by a bitter taste and an iodoform- or hay-like fragrance; these result from the chemicals picrocrocin and safranal.^[4][5] A carotenoid dye, crocin, allows saffron to impart a rich golden-yellow hue to dishes and textiles. Saffron has further medicinal applications.

The English word saffron stems from the Latin word safranum via the 12th-century Old French term safran. Latin safranum is also the source of the Italian zafferano and Spanish azafrán.^[6] Safranum derives via Persian/Farsi زعفران (za'ferân) ultimately from the Arabic word زَعْفَرَان (za'farān), which is itself derived from the adjective أَصْفَر (aṣfar, "yellow").^[5][7]

Biology

The domesticated saffron crocus (C. sativus) is an autumn-flowering perennial plant unknown in the wild. It is a sterile triploid form, possibly of the eastern Mediterranean autumn-flowering Crocus cartwrightianus^[8][9][10] that originated in Crete—not, as was once generally believed, in Central Asia.^[5] The saffron crocus resulted when C. cartwrightianus was subjected to extensive artificial selection by growers seeking longer stigmas. Being sterile, the plant's purple flowers fail to produce viable seeds; reproduction depends on human assistance: corms, underground bulb-like starch-storing organs, must be dug up, broken apart, and replanted. A corm survives for one season, reproducing via this division into up to ten "cormlets" that yield new plants.^[8] Corms are small brown globules up to 4.5 centimetres (1.8 in) in diameter and are shrouded in a dense mat of parallel fibers.

Morphology
	→  Stigma
	→  Stamens
	→  Corolla
	→  Corm

After aestivating in summer, the plant sends up five to eleven narrow and nearly vertical green leaves, each up to 40 cm (16 in) in length. In autumn, purple buds appear. 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.^[11] Upon flowering, plants average less than 30 cm (12 in) in height.^[12] A three-pronged style emerges from each flower. Each prong terminates with a vivid crimson stigma 25–30 mm (0.98–1.2 in) in length.^[8]

Cultivation

Saffron crocus flowers in Osaka Prefecture, Japan

Saffron crocus thrives in climates similar to that of the Mediterranean maquis or the North American chaparral, where hot, dry summer breezes blow across arid and semi-arid lands. The plant can nonetheless tolerate cold winters by surviving frosts as low as −10 °C (14 °F) and short periods of snow cover.^[8][13] Irrigation is required if not grown in moist environments such as Kashmir, where annual rainfall averages 1,000–1,500 mm (39–59 in); saffron-growing regions in Greece (500 mm or 20 in annually) and Spain (400 mm or 16 in) are far drier. Rainfall timing is key: generous spring rains and drier summers are optimal. Rain immediately preceding flowering boosts saffron yields; rainy or cold weather during flowering spurs disease and low yields. Persistently damp and hot conditions harm crops,^[14] as do the digging actions of rabbits, rats, and birds. Nematodes, leaf rusts, and corm rot pose other threats.

Plants grow best in strong and direct sunlight; they fare poorly in shady conditions. Planting is thus best done in fields that slope towards the sunlight (i.e., south-sloping in the Northern Hemisphere), maximizing sun exposure. Planting is mostly done in June in the Northern Hemisphere, where corms are lodged 7 to 15 centimetres (2.8–5.9 in) deep. Planting depth and corm spacing, in concert with climate, are critical factors affecting yields. Mother corms planted more deeply yield higher-quality saffron, though they produce fewer flower buds and daughter corms. Italian growers have found that planting corms 15 centimetres (5.9 in) deep and in rows spaced 2–3 cm apart optimizes thread yields, whereas planting depths of 8–10 cm optimizes flower and corm production. Greek, Moroccan, and Spanish growers have devised different depths and spacings to suit their local climates.

Saffron crocuses grow best in friable, loose, low-density, well-watered, and well-drained clay-calcareous soils with high organic content. Raised beds are traditionally used to promote good drainage. Soil organic content was historically boosted via application of some 20–30 tonnes of manure per hectare. Afterwards—and with no further manure application—corms were planted.^[15] After a period of dormancy through the summer, the corms send up their narrow leaves and begin to bud in early autumn. Only in mid-autumn do they flower. Harvests are by necessity a speedy affair: after blossoming at dawn, flowers quickly wilt as the day passes.^[16] Furthermore, saffron crocuses bloom within a period of one or two weeks.^[17] Approximately 150 flowers yield 1 gram (0.035 oz) of dry saffron threads; to produce 12 g of dried saffron (72 g freshly harvested), 1 kg of flowers are needed (1 lb for 0.2 oz of dried saffron). One fresh-picked flower yields an average 30 milligrams (0.46 gr) of fresh saffron or 7 milligrams (0.11 gr) of dried saffron.^[15]

Chemistry

Crocin
Esterification reaction between crocetin and gentiobiose
	—  β-D-gentiobiose
	—  Crocetin

Picrocrocin and safranal
Chemical structure of picrocrocin[18]
	—  Safranal moiety
	—  β-D-glucopyranose derivative

Saffron contains more than 150 volatile and aroma-yielding compounds. It also has many nonvolatile active components,^[19] 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 (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.^[19] Crocins themselves are a series of hydrophilic carotenoids that are either monoglycosyl or diglycosyl polyene esters of crocetin.^[19] Meanwhile, 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 (non-fatty) foods such as rice dishes.^[20]

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-element 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. Significantly, picrocrocin is a truncated version (produced via oxidative cleavage) of the carotenoid zeaxanthin and is the glycoside of the terpene aldehyde safranal. The reddish-coloured^[21] zeaxanthin is, incidentally, one of the carotenoids naturally present within the retina of the human eye.

When saffron is dried after its harvest, the heat, combined with enzymatic action, splits picrocrocin to yield D-glucose and a free safranal molecule.^[18] Safranal, a volatile oil, gives saffron much of its distinctive aroma.^[4][22] Safranal is less bitter than picrocrocin and may comprise up to 70% of dry saffron's volatile fraction in some samples.^[21] A second element underlying saffron's aroma is 2-hydroxy-4,4,6-trimethyl-2,5-cyclohexadien-1-one, the scent of which has been described as "saffron, dried hay like".^[23] Chemists found this to be the most powerful contributor to saffron's fragrance despite its being present in a lesser quantity than safranal.^[23] Dry saffron is highly sensitive to fluctuating pH levels, and rapidly breaks down chemically in the presence of light and oxidizing agents. It must therefore be stored away in air-tight containers in order to minimise contact with atmospheric oxygen. Saffron is somewhat more resistant to heat.

Crocus sativus has been shown to have antidepressant effects; two active ingredients are crocin and safranal.^[24]

History

A detail of the "Saffron Gatherers" fresco from the "Xeste 3" building. The fresco is one of many dealing with saffron that were found at the Bronze Age settlement of Akrotiri, Santorini.

The history of saffron cultivation reaches back more than 3,000 years.^[25] The wild precursor of domesticated saffron crocus was Crocus cartwrightianus. Human cultivators bred wild specimens by selecting for unusually long stigmas. Thus, a sterile mutant form of C. cartwrightianus, C. sativus, emerged in late Bronze Age Crete.^[26] Experts believe saffron was first documented in a 7th century BC Assyrian botanical reference compiled under Ashurbanipal. Since then, documentation of saffron's use over the span of 4,000 years in the treatment of some 90 illnesses has been uncovered.^[27]

Asia

The 17.8 metres (58 ft) monolith of Gomateshwara, dating to 978–993 AD, is anointed with saffron every 12 years by thousands of devotees as part of the Mahamastakabhisheka festival.

Saffron-based pigments have been found in 50,000 year-old depictions of prehistoric beasts in what is today Iraq.^[28][29] Later, the Sumerians used wild-growing saffron in their remedies and magical potions.^[30] Saffron was an article of long-distance trade before the Minoan palace culture's 2nd millennium BC peak. Ancient Persians cultivated Persian saffron (Crocus sativus 'Hausknechtii') in Derbena, Isfahan, and Khorasan by the 10th century BC. At such sites, saffron threads were woven into textiles,^[31] ritually offered to divinities, and used in dyes, perfumes, medicines, and body washes.^[32] Thus, saffron threads would be scattered across beds and mixed into hot teas as a curative for bouts of melancholy. Non-Persians also feared the Persians' usage of saffron as a drugging agent and aphrodisiac.^[33] During his Asian campaigns, Alexander the Great used Persian saffron in his infusions, rice, and baths as a curative for battle wounds. Alexander's troops mimicked the practice and brought saffron-bathing back to Greece.^[34]

Theories explaining saffron's arrival in South Asia conflict. Traditional Kashmiri and Chinese accounts date its arrival anywhere between 900–2500 years ago.^[35][36][37] Meanwhile, historians studying ancient Persian records date the arrival to sometime prior to 500 BC,^[38] attributing it to either Persian transplantation of saffron corms to stock new gardens and parks^[39] or to a Persian invasion and colonization of Kashmir. Phoenicians then marketed Kashmiri saffron as a dye and a treatment for melancholy.^[33] From there, saffron use in foods and dyes spread throughout South Asia. Buddhist monks in India adopted saffron-coloured robes after the Buddha Siddhartha Gautama's death.^[40] However, the robes were not dyed with costly saffron but turmeric, a less expensive dye, or jackfruit.^[41]

Some historians believe that saffron first came to China with Mongol invaders by way of Persia.^[42] On the other hand, saffron is mentioned in ancient Chinese medical texts, including the forty-volume Shennong Bencaojing (神農本草經—"Shennong's Great Herbal", also known as Pen Ts'ao or Pun Tsao) pharmacopoeia, a tome dating from 200–300 BC. Traditionally attributed to the legendary Yan ("Fire") Emperor (炎帝) Shennong, it documents 252 phytochemical-based medical treatments for various disorders.^[40][43] Yet around the 3rd century AD, the Chinese were referring to saffron as having a Kashmiri provenance. For example, Wan Zhen, a Chinese medical expert, reported that "[t]he habitat of saffron is in Kashmir, where people grow it principally to offer it to the Buddha." Wan also reflected on how saffron was used in his time: "The [saffron crocus] flower withers after a few days, and then the saffron is obtained. It is valued for its uniform yellow colour. It can be used to aromatise wine."^[37]

The Tamils call saffron as "gnaazhal poo" and it is used in Siddha medicines for several purposes especially for infants when they get cold associated with head-ache; to make delivery less painful extra.^[44]

Europe/Mediterranean

Minoans portrayed saffron in their palace frescoes by 1500–1600 BC, showing saffron's use as a therapeutic drug.^[45][46] Later, Greek legends told of sea voyages to Cilicia. There, adventurers hoped to procure what they believed was the world's most valuable saffron.^[47] Another legend tells of Crocus and Smilax, whereby Crocus is bewitched and transformed into the original saffron crocus.^[48] Ancient Mediterranean peoples—including perfumers in Egypt, physicians in Gaza, townspeople in Rhodes,^[49] and the Greek hetaerae courtesans—used saffron in their perfumes, ointments,^[50] potpourris, mascaras, divine offerings, and medical treatments.^[50]

This ancient Minoan fresco from Knossos, Crete shows a man (stooped blue figure) gathering the saffron harvest.

In late Hellenistic Egypt, Cleopatra used saffron in her baths so that lovemaking would be more pleasurable.^[51] Egyptian healers used saffron as a treatment for all varieties of gastrointestinal ailments.^[52] Saffron was also used as a fabric dye in such Levant cities as Sidon and Tyre.^[53] Aulus Cornelius Celsus prescribes saffron in medicines for wounds, cough, colic, and scabies, and in the mithridatium.^[54] Such was the Romans' love of saffron that Roman colonists took their saffron with them when they settled in southern Gaul, where it was extensively cultivated until Rome's fall. Competing theories state that saffron only returned to France with 8th century AD Moors or with the Avignon papacy in the 14th century AD.^[55]

Medieval European illuminated manuscripts, such as this 13th century depiction of Archbishop of Canterbury Thomas Becket's assassination, often used saffron dyes to provide hues of yellow and orange.

In Europe, saffron cultivation declined steeply following the Roman Empire's fall. Saffron was reintroduced when the Islamic civilization "Al-Andalus" spread to Spain, France, and Italy.^[56] During the 14th century Black Death, demand for saffron-based medicine skyrocketed, and much saffron had to be imported via Venetian and Genoan ships from southern and Mediterranean lands^[57] such as Rhodes. The theft of one such shipment by noblemen sparked the fourteen-week long "Saffron War".^[57] The conflict and resulting fear of rampant saffron piracy spurred significant saffron cultivation in Basel, which grew prosperous.^[58] Cultivation and trade then spread to Nuremberg, where epidemic levels of saffron adulteration brought on the Safranschou code, under which saffron adulterators were fined, imprisoned, and executed.^[59] Soon after, saffron cultivation spread throughout England, especially Norfolk and Suffolk. The Essex town of Saffron Walden, named for its new specialty crop, emerged as England's prime saffron growing and trading center. However, an influx of more exotic spices such as chocolate, coffee, tea, and vanilla from newly contacted Eastern and overseas countries caused European cultivation and usage of saffron to decline.^[60][61] Only in southern France, Italy, and Spain, did significant cultivation endure.^[62]

Europeans brought saffron to the Americas when immigrant members of the Schwenkfelder Church left Europe with a trunk containing saffron corms; indeed, many Schwenkfelders had widely grown saffron in Europe.^[63] By 1730, the Pennsylvania Dutch were cultivating saffron throughout eastern Pennsylvania. Spanish colonies in the Caribbean bought large amounts of this new American saffron, and high demand ensured that saffron's list price on the Philadelphia commodities exchange was set equal to that of gold.^[64] The trade with the Caribbean later collapsed in the aftermath of the War of 1812, when many saffron-transporting merchant vessels were destroyed.^[65] Yet the Pennsylvania Dutch continued to grow lesser amounts of saffron for local trade and use in their cakes, noodles, and chicken or trout dishes.^[66] American saffron cultivation survived into modern times mainly in Lancaster County, Pennsylvania.^[63]

Trade and use

Saffron is one of the three essential ingredients in the Spanish paella valenciana, and is responsible for its characteristic brilliant yellow colouring.

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 somewhat bitter. Saffron also contributes a luminous yellow-orange colouring to foods. Saffron is widely used in Iranian (Persian), Arab, Central Asian, European, Indian, Turkish, and Cornish cuisines. Confectionaries and liquors also often include saffron. Common saffron substitutes include safflower (Carthamus tinctorius, which is often sold as "Portuguese saffron" or "assafroa") and turmeric (Curcuma longa). Medicinally, saffron has a long history as part of traditional healing; modern medicine has also discovered saffron as having anticarcinogenic (cancer-suppressing),^[19] anti-mutagenic (mutation-preventing), immunomodulating, and antioxidant-like properties.^[19][67][68] Early studies show that saffron may protect the eyes from the direct effects of bright light and retinal stress apart from slowing down macular degeneration and retinitis pigmentosa.^[69][70][71] Saffron has also been used as a fabric dye, particularly in China and India, and in perfumery.^[72]

World saffron cultivation patterns
	—  Major growing regions
	—  Major producing nations
	—  Minor growing regions
	—  Minor producing nations
	—  Major trading centres (current)
	—  Major trading centres (historical)

Most saffron is grown in a belt of land ranging from the Mediterranean in the west to Kashmir in the east. Annually, around 300 tonnes of saffron are produced worldwide.^[5] Iran, Spain, India, Greece, Azerbaijan, Morocco, and Italy, in decreasing order of production, are the major producers of saffron.

A pound of dry saffron requires 50,000–75,000 flowers, the equivalent of a football field's area of cultivation (110,000-170,000 flowers or two football fields for a kilogram).^[73][74] Some forty hours of labour are needed to pick 150,000 flowers.^[75] Stigmas are dried quickly upon extraction and (preferably) sealed in airtight containers.^[76] Saffron prices at wholesale and retail rates range from US$500 to US$5,000 per pound (US$1,100–11,000/kg)—equivalent to £2,500/€3,500 per pound or £5,500/€7,500 per kilogram. In Western countries, the average retail price is $1,000/£500/€700 per pound (US$2,200/£1,100/€1,550 per kilogram).^[2] A pound comprises between 70,000 and 200,000 threads. Vivid crimson colouring, slight moistness, elasticity, and lack of broken-off thread debris are all traits of fresh saffron.

Cultivars

Saffron threads (red-coloured stigmas) mixed with styles (yellow) from Iran

Several saffron cultivars are grown worldwide. Spain's varieties, including the tradenames 'Spanish Superior' and 'Creme', are generally mellower in colour, flavour, and aroma; they are graded by government-imposed standards. Italian varieties are slightly more potent than Spanish, while the most intense varieties tend to be Iranian in origin. Westerners may face significant obstacles in obtaining saffron from India. For example, India has banned the export of high-grade saffron abroad. Aside from these, various "boutique" crops are available from New Zealand, France, Switzerland, England, the United States, and other countries, some organically grown. In the U.S., Pennsylvania Dutch saffron—known for its earthy notes—is marketed in small quantities.^[63][77]

Close-up of a single crocus thread (the dried stigma). Actual length is about 20 millimetres (0.79 in).

Consumers regard certain cultivars as "premium" quality. The "Aquila" saffron (zafferano dell'Aquila)—defined by high safranal and crocin content, shape, unusually pungent aroma, and intense colour—is grown exclusively on eight hectares in the Navelli Valley of Italy's Abruzzo region, near L'Aquila. It was first introduced to Italy by a Dominican monk from Inquisition-era Spain. But in Italy the biggest saffron cultivation, for quality and quantity, is in San Gavino Monreale, Sardinia. There, saffron is grown on 40 hectares (60% of Italian production); it also has very high crocin, picrocrocin, and safranal content. Another is the Kashmiri "Mongra" or "Lacha" saffron (Crocus sativus 'Cashmirianus'), which is among the most difficult for consumers to obtain. Repeated droughts, blights, and crop failures in Kashmir, combined with an Indian export ban, contribute to its high prices. Kashmiri saffron is recognisable by its extremely dark maroon-purple hue, among the world's darkest, which suggests the saffron's strong flavour, aroma, and colourative effect.

Grade

Saffron is graded via laboratory measurement of crocin (colour), picrocrocin (taste), and safranal (fragrance) content. Determination of non-stigma content ("floral waste content") and other extraneous matter such as inorganic material ("ash") are also key. Grading standards are set by the International Organization for Standardization, a federation of national standards bodies. ISO 3632 deals exclusively with saffron and establishes four empirical colour intensity grades: IV (poorest), III, II, and I (finest quality). Samples are assigned grades by gauging the spice's crocin content, revealed by measurements of crocin-specific spectroscopic absorbance. Absorbance is defined as A_λ = − log(I / I₀), with A_λ as absorbance (Beer-Lambert law) and indicates degree of transparency (I / I₀, the ratio of light intensity exiting the sample to that of the incident light) to a given wavelength of light.

For saffron, absorbance is determined for the crocin-specific photon wavelength of 440 nm in a given dry sample of spice.^[78] Higher absorbances at this wavelength imply greater crocin concentration, and thus a greater colourative intensity. These data are measured through spectrophotometry reports at certified testing laboratories worldwide. These colour grades proceed from grades with absorbances lower than 80 (for all category IV saffron) up to 190 or greater (for category I). The world's finest samples (the selected most red-maroon tips of stigmas picked from the finest flowers) receive absorbance scores in excess of 250. Market prices for saffron types follow directly from these ISO scores.^[78] However, many growers, traders, and consumers reject such lab test numbers. They prefer a more holistic method of sampling batches of thread for taste, aroma, pliability, and other traits in a fashion similar to that practiced by practised wine tasters.^[79]

Despite such attempts at quality control and standardisation, an extensive history of saffron adulteration—particularly among the cheapest grades—continues into modern times. Adulteration was first documented in Europe's Middle Ages, when those found selling adulterated saffron were executed under the Safranschou code.^[80] Typical methods include mixing in extraneous substances like beets, pomegranate fibers, red-dyed silk fibers, or the saffron crocus's tasteless and odorless yellow stamens. Other methods included dousing saffron fibers with viscid substances like honey or vegetable oil. However, powdered saffron is more prone to adulteration, with turmeric, paprika, and other powders used as diluting fillers. Adulteration can also consist of selling mislabeled mixes of different saffron grades.^[81] Thus, in India, high-grade Kashmiri saffron is often sold mixed with cheaper Iranian imports; these mixes are then marketed as pure Kashmiri saffron, a development that has cost Kashmiri growers much of their income.^[82][83]

See also

Wikimedia Commons has media related to: Crocus sativus

Topics related to saffron:   Saffron • History • Trade and use

Notes

Saffron crocuses flowering in a garden in Osaka Prefecture (大阪府), Kansai, Honshū, Japan

A saffron crocus flower

References

External links

• Media related to Crocus sativus at Wikimedia Commons
• Duke, Jim. "Crocus sativus". Dr. Duke's Phytochemical and Ethnobotanical Databases. http://sun.ars-grin.gov:8080/npgspub/xsql/duke/plantdisp.xsql?taxon=318. Retrieved 5 August 2009. 

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