Saffron

? Saffron crocus
A saffron crocus flower with red stigmas.
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Liliopsida Order: Asparagales Family: Iridaceae Genus: Crocus Species: C. sativus
Binomial name
Crocus sativus L.

Saffron ( IPA: ['sæfɹən]) is a spice derived from the flower of the saffron crocus (Crocus sativus), a species of crocus in the family Iridaceae. The flower's three stigmas (the distal ends of the plant's carpels, or female reproductive organs) and parts of its style (a stalk connecting the stigmas to the rest of the plant) are often dried and used in cooking as a seasoning and colouring agent. Saffron, which has for decades been the world's most expensive spice by weight, is native to Southwest Asia. It was first cultivated in the vicinity of Greece.

Saffron is characterised by a bitter taste and an iodoform- or hay-like fragrance; these are caused by the chemicals picrocrocin and safranal. It also contains a carotenoid dye, crocin, that gives food a rich golden-yellow hue. These qualities make saffron a much sought-after ingredient in many foods worldwide. Saffron also has medicinal applications.

The word saffron originated from the 12th century Old French term safran, which derives from the Latin word safranum. Safranum is also related to the Italian zafferano and Spanish azafrán. Safranum comes from the Arabic word asfar (أَصْفَر), which means " yellow", via the paronymous za‘faran (زَعْفَرَان), the name of the spice in Arabic.

Biology

Saffron crocus morphology
	→ Stigma (terminus of pistil).
	→ Stamens ( male organs).
	→ Corolla (whorl of petals).
	→ Corm (propagation organ).

The domesticated saffron crocus C. sativus is a fall- flowering perennial plant that is unknown in the wild. It is a sterile triploid mutant of the eastern Mediterranean fall-flowering Crocus cartwrightianus. Botanical research indicates that C. cartwrightianus originated in Crete, not in Central Asia as once generally believed. The saffron crocus was the subject of artificial selection by growers who bred for abnormally long stigmas. Being sterile, the saffron crocus' purple flowers fail to produce viable seeds. Because of this, its reproduction is entirely dependent on human assistance: the corms (underground bulb-like starch-storing organs) must be manually dug up, broken apart, and replanted. A corm survives for only one season, and reproduces by division into up to ten "cormlets". The corms then grow into new individual plants. The corms appear as small brown globules, up to 4.5 centimeters in diameter, each shrouded in a mat of parallel fibers.

After a period of dormancy ( aestivation) in the summer, five to eleven narrow and nearly vertical green leaves emerge from the ground. These leaves can grow up to 40 cm long. Later, in autumn, purple buds develop. Only in October, after most other flowering plants have released their seeds, does the saffron crocus suddenly develop its brilliantly-coloured purple flowers. These can range from a light pastel shade of lilac to a darker and striated mauve. Upon flowering, the saffron crocus remains, on average, less than 30 cm in height. Inside each flower is a three-pronged style terminating in three crimson stigmas. These stigmas may measure anywhere from 25 to 30 mm in length.

Cultivation

Saffron crocuses under cultivation in Italy.

The saffron crocus thrives in climates similar to that of the Mediterranean maquis. Thus, it flourishes in such places as the North American chaparral, where hot, dry breezes blow across arid and semi-arid lands in the summer. Nevertheless, the plant can tolerate cold winters, surviving frosts as cold as -10°C and short periods of snow cover. If it is not grown in a high-rainfall environment, the saffron crocus needs irrigation. For example, in Kashmir, annual rainfall averages 1000–1500 mm, and so Kashmiri saffron is grown without irrigation when rainfall is normal. In the much drier saffron-growing regions of Greece, where rainfall averages 500 mm, and Spain, where it averages 400 mm, irrigation is required. The saffron crocus thrives in spring rains which are followed by relatively dry summers. However, rains falling immediately before flowering cause high saffron yields. On the other hand, rain or cold weather occurring during flowering promotes disease. Constantly damp and hot conditions also harm saffron yields, as do the digging actions of rabbits, rats, and birds. Parasites such as nematodes, leaf rusts, and corm rot also pose threats.

Planting is best done in fields that slope towards the south, maximizing the crocuses' exposure to the sun. Saffron plants need strong direct sunlight and do not thrive as shade plants. In the Northern Hemisphere, planting is done in June. The corms are planted 7 to 15 cm beneath the surface of the soil. Harvest yield and quality are affected by the climate, planting depth, and corm spacing. Mother corms that are planted more deeply yield fewer flower buds and daughter corms, but produce higher-quality saffron. In the conditions found in Italy, planting the corms 15 cm beneath the surface produces optimal saffron threads, while a shallower planting of 8–10 cm yields the most flowers and daughter corms. In Italy, the corms are planted 2–3 cm apart. Optimal planting practices vary widely between Italy, Greece, Morocco, and Spain.

The 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. Historically, the organic content of soil for saffron cultivation was boosted with the application of some 20–30 tonnes of manure per hectare. Afterwards, corms were planted, and no further manure application was needed thereafter. After a period of dormancy through the summer, the corms send up their narrow leaves and begin to bud in autumn. Only in October (in the Northern Hemisphere) do the plants begin to flower. Harvesting of flowers is by necessity a speedy affair. Upon their flowering at dawn, the flowers quickly wilt under the noonday sun. In addition, all saffron crocus flowers bloom within a narrow window of one to two weeks.

Chemistry

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

Saffron contains in excess of 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-(ß-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. Crocins themselves are a series of hydrophilic carotenoids that are either monoglycosyl or diglycosyl polyene esters of crocetin. 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.

Picrocrocin and safranal
Chemical structure of picrocrocin.
	— Safranal moiety.
	— β- D-glucopyranose derivative.

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-dien-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 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. 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 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". Chemists found this to be the most powerful contributor to saffron's fragrance despite its being present in a lesser quantity than safranal. The glycoside crocin is water-soluble, and so it does not as readily contribute its yellow colouring to oily substances. As such, it is ideal for colouring water-based foods, such as rice. 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.

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 ancient Minoan settlement of Akrotiri, Santorini.

The history of saffron cultivation reaches back more than 3,000 years. 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. 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. Saffron has been used as a spice and medicine in the Mediterranean region since then, with usage and cultivation slowly spreading to other parts of Eurasia as well as North Africa and North America. In the last several decades, saffron cultivation has spread to Oceania.

Greco-Roman

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

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

In late Hellenistic Egypt, Cleopatra used saffron in her baths so that lovemaking would be more pleasurable. Egyptian healers used saffron as a treatment for all varieties of gastrointestinal ailments. Saffron was also used as a fabric dye in such Levant cities as Sidon and Tyre. 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 271 AD 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.

Asian

The 17.8 m monolith of Jain prophet Bhagavan Gomateshwara Bahubali, which was carved between 978–993 AD and is located in Shravanabelagola, India, 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. Later, the Sumerians used wild-growing saffron in their remedies and magical potions. Saffron was thus an article of long-distance trade before the Minoan palace culture's 2nd millennium BC peak. Saffron was also honored in the Hebrew Song of Solomon. 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, ritually offered to divinities, and used in dyes, perfumes, medicines, and body washes. 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. During his Asian campaigns, Alexander the Great used Persian saffron in his teas, rice, and baths as a curative for battle wounds. Alexander's troops mimicked the practice and brought saffron-bathing back to Greece.

Theories of saffron's arrival in South Asia conflict. Traditional Kashmiri and Chinese accounts give arrival dates between 900–2500 years ago. Meanwhile, many historians studying ancient Persian records date the arrival to sometime prior to 500 BC. They attribute this to either Persian transplantation of saffron corms to stock new gardens and parks or to a Persian invasion and colonization of Kashmir. Phoenicians then marketed Kashmiri saffron as a dye and a treatment for melancholy. From there, saffron use in foods and dyes spread throughout South Asia. For example, Buddhist monks in India adopted saffron-coloured robes after the Buddha Siddhartha Gautama's death.

Historians believe that saffron first came to China with Mongol invaders by way of Persia. Yet saffron is mentioned in ancient Chinese medical texts, including the Pun Tsao ("Great Herbal") pharmacopoeia (pp. 1552–78), a tome dating from around 1600 BC (and attributed to Emperor Shen-Ung) which documents thousands of phytochemical-based medical treatments for various disorders. 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."

Post-Classical European

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 Moorish civilization spread to Spain, France, and Italy. 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 such as Rhodes. The theft of one such shipment by noblemen sparked the fourteen-week long "Saffron War". The conflict and resulting fear of rampant saffron piracy spurred significant saffron cultivation in Basel, which grew prosperous. Cultivation and trade then spread to Nuremberg, where epidemic levels of saffron adulteration brought on the Safranschou code, which fined, imprisoned, and executed saffron adulterers. 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 — chocolate, coffee, tea, and vanilla — from newly-contacted Eastern and overseas countries caused European cultivation and usage of saffron to decline. Only in southern France, Italy, and Spain, did significant cultivation endure.

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. 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. The trade with the Caribbean later collapsed in the aftermath of the War of 1812, when many saffron-transporting merchant vessels were destroyed. 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. American saffron cultivation survived into modern times mainly in Lancaster County, Pennsylvania.

Usage and trade

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 been noted also as hay-like and yet somewhat bitter. Saffron also contributes a luminous yellow-orange colouring to foods. For this, it is widely used in Arab, Central Asian, European, Indian, Iranian, and Moroccan cuisines. Confectionaries and liquors also often include saffron. Common saffron substitutes include safflower (Carthamus tinctorius) 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), anti-mutagenic (mutation-preventing), immunomodulating, and antioxidant-like properties. Nevertheless, saffron is lethal at high doses. Saffron has also been used as a fabric dye — particularly in China and India — and in perfumery.

World saffron cultivation patterns
A map showing the primary saffron-producing nations.
	— Major growing regions.
	— Major producing nations.
	— Minor growing regions.
	— Minor producing nations.
	— Major trading centers (current).
	— Major trading centers (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. Iran, Spain, India, Greece, Azerbaijan, Morocco, and Italy (in decreasing order of production) are the major producers of saffron. A pound of dry saffron (0.45 kg) requires 50,000–75,000 flowers, the equivalent of a football field's area of cultivation. Some forty hours of frenetic day-and-night labour are needed to pick 150,000 flowers. Upon extraction, stigmas are dried quickly and (preferably) sealed in airtight containers. Saffron prices at wholesale and retail rates range from US$500/pound to US$5000/pound. In Western countries, the average retail price is $1,000/pound. Between 70,000 and 200,000 threads comprise a pound. Vivid crimson colouring, slight moistness, elasticity, recent harvest date, and lack of broken-off thread debris are all traits of fresh saffron.

Cultivars

Saffron threads from Iran.

Several saffron cultivars are grown worldwide. Spain, a major saffron exporter, generally produces mellow varieties with less intense colour, flavour, and aroma. Spanish varieties include the 'Spanish Superior' and 'Creme' tradenames, and are graded via government-regulated minimum standards. Most Italian saffron is more potent in these characteristics. However, the world's most intense and valuable varieties disproportionately have Macedonian Greek, Iranian, and Kashmiri Indian pedigrees. Westerners may face significant obstacles in obtaining saffron from these countries. For example, the United States has banned the import of Iranian saffron and India has banned the export of high-grade saffron abroad. Aside from these, various "boutique" crops are available from places such as New Zealand, France, Switzerland, England, and the United States. In the U.S., for example, Pennsylvania Dutch saffron — which is known for its earthy notes — is available in relatively small quantities.

There are a handful of what are generally considered by consumers to be "premium" saffron types. For example, 'Aquila' saffron ( Italian: zafferano del L'Aquila) is cultivated in the Abruzzo region of Italy's Navelli Valley. There, saffron is grown on some eight hectares of land. At present, this is its exclusive domain worldwide. It is distinguished by the shape and colour of its stigmas and styles as well as its high safranal content. These give 'Aquila' saffron an unusually pungent aroma. In addition, high crocin content results in exceptional colouring ability. 'Aquila' was first introduced to Italy from Inquisition-era Spain by a Dominican monk. Thereafter, for the duration of the Middle Ages, 'Aquila' became Europe's most sought-after cultivars. But in Italy the biggest saffron cultivation, for quality and quantity, is in San Gavino Monreale, Sardinia. There, saffron is grown on 40 hectares (comprising 60% of Italian production); it also has very high crocin, picrocrocin, and safranal content. Another premium saffron is the Kashmiri "Mongra" or "Lacha" saffron (Crocus sativus 'Cashmirianus'), which is among the most difficult and expensive for non-Indian consumers to obtain. It is even hard for Indian consumers to obtain, as most stores in India sell the cheaper Spanish saffron. This is due to repeated droughts, blights, and crop failures in Kashmir, combined with an Indian export ban. 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.

Grades

Powdered saffron stored in an airtight glass vial.

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). Saffron samples are then assigned to one of these grades by gauging the spice's crocin content, which is revealed by measurements of crocin-specific spectroscopic absorbance. Absorbance is defined as A_λ = − log(I / I₀), with A_λ as absorbance. It is a measure of a given substance's transparency (I / I₀, the ratio of light intensity passing through 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. Higher absorbances at this wavelength imply greater crocin concentration, and thus a greater colourative intensity. These data are measured through photospectroscopy 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 very 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. 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.

Despite these attempts at quality control and standardisation, a rich history of saffron adulteration continues into the present. Saffron adulteration was first documented in Europe's Middle Ages, when those found guilty of selling adulterated saffron were executed under the Safranschou code. Traditional methods include mixing in extraneous substances; examples included beet, pomegranate fibers, red-dyed silk fibers, or the saffron crocus's tasteless and odorless yellow stamens, with the saffron threads or powder in order to increase its mass. Fraudulent practices also included the dousing of genuine saffron fibers with viscid substances such as honey or vegetable oil. Powdered saffron is far more susceptible to adulteration, however. Turmeric, paprika, and other substances were and still are often combined with saffron powder. Cheaper grades and samples of saffron are more likely to be adulterated. In addition, adulteration can arise from the illegal mixing of relatively inexpensive (lower) saffron grades with premium categories. Thus, in India, rich and premium Kashmiri saffron is often sold mixed with cheaper and lower quality Iranian imports. These mixes are then marketed as pure Kashmiri saffron, a development that has cost Kashmiri growers much of their income.

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