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Saffron

2007 Schools Wikipedia Selection. Related subjects: Food and agriculture;
Plants

                iSaffron crocus
   A saffron crocus flower with red stigmas.
   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: [ˈsæf.ɹən] / [ˈsæf.ɹɔn]) is a spice derived from the
   flower of the saffron crocus (Crocus sativus), a species of crocus in
   the family Iridaceae. The flower has three stigmas, which are the
   distal ends of the plant's carpels. Together with its style, the stalk
   connecting the stigmas to the rest of the plant, these components 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 traits make saffron a much-sought 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 aṣfar (أَصْفَر), which means " yellow," via the
   paronymous zaʻfarān (زَعْفَرَان), the name of the spice in Arabic.

Biology

                        Saffron crocus morphology
   Crocus sativus (saffron crocus) botanical illustration from Kohler's
                         Medicinal Plants (1887).
    →  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 unknown in the wild, and is a sterile triploid mutant
   of the eastern Mediterranean fall-flowering Crocus cartwrightianus.
   According to botanical research, C. cartwrightianus originated in
   Crete, not—as was once generally believed—in Central Asia. The saffron
   crocus resulted when C. cartwrightianus was subjected to extensive
   artificial selection by growers who desired elongated stigmas. Being
   sterile, the saffron crocus's purple flowers fail to produce viable
   seeds—thus, reproduction is 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,
   reproducing via division into up to ten "cormlets" that eventually give
   rise to new plants. The corms are small brown globules up to 4.5  cm in
   diameter and are shrouded in a dense mat of parallel fibers.

   After a period of aestivation in summer, five to eleven narrow and
   nearly vertical green leaves—growing up to 40 cm in length—emerge from
   the ground. In autumn, purple buds appear. Only in October, after most
   other flowering plants have released their seeds, does it develop its
   brilliantly-hued flowers, ranging from a light pastel shade of lilac to
   a darker and more striated mauve. Upon flowering, it averages less than
   30 cm in height. Inside each flower is a three-pronged style; in turn,
   each prong terminates with a crimson stigma 25–30  mm in length.

Cultivation

   Two saffron crocus flowers in Osaka Prefecture, Japan.
   Enlarge
   Two saffron crocus flowers in Osaka Prefecture, Japan.

   The 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. Nevertheless, the
   plant can tolerate cold winters, surviving frosts as cold as −10°C and
   short periods of snow cover. However, if not grown in wet environments
   like Kashmir (where rainfall averages 1000–1500 mm annually),
   irrigation is needed—this is true in the saffron-growing regions of
   Greece (500 mm of rainfall annually) and Spain (400 mm). Rainfall
   timing is also key: generous spring rains followed by relatively dry
   summers are optimal. In addition, rainfall occurring immediately prior
   to flowering also boosts saffron yields; nevertheless, rainy or cold
   weather occurring during flowering promotes disease, thereby reducing
   yields. Persistently damp and hot conditions also harm yields, as do
   the digging actions of rabbits, rats, and birds. Parasites such as
   nematodes, leaf rusts, and corm rot also pose significant threats.
                  Saffron crocus flower yields^[*]
   Country                    Yield ( kg/ ha)
    Spain                           6–29
    Italy                          10–16
   Greece                           4–7
    India                           2–7
   Morocco                        2.0–2.5
                       Source: Deo 2003, p. 3
   [*]—Yields specify flower weight, not final dry saffron weight.

   Saffron plants grow best in strong and direct sunlight, and fare poorly
   in shady conditions. Thus, planting is best done in fields that slope
   towards the sunlight (i.e. south-sloping in the Northern Hemisphere),
   maximizing the crocuses' sun exposure. In the Northern Hemisphere,
   planting is mostly done in June, with corms planted some 7–15 cm deep.
   Planting depth and corm spacing—along with climate—are both critical
   factors impacting plant yields. Thus, mother corms planted more deeply
   yield higher-quality saffron, although they produce fewer flower buds
   and daughter corms. With such knowledge, Italian growers have found
   that planting corms 15 cm deep and in rows spaced 2–3 cm apart
   optimizes threads yields, whereas planting depths of 8–10 cm optimizes
   flower and corm production. Meanwhile, Greek, Moroccan, and Spanish
   growers have devised different depths and spacings to suit their own
   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.
   Historically, soil organic content was boosted via application of some
   20–30 tonnes of manure per hectare. Afterwards—and with no further
   manure application—corms were planted. 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 the plants begin to flower.
   Harvesting of flowers is by necessity a speedy affair: after their
   flowering at dawn, flowers quickly wilt as the day passes. Furthermore,
   saffron crocuses bloom within a narrow window spanning one or two
   weeks. Approximately 150 flowers yield 1  g of dry saffron threads; to
   produce 12 g of dried saffron (72 g freshly harvested), 1  kg of
   flowers are needed. On average, one freshly-picked flower yields 0.03 g
   of fresh saffron, or 0.007 g of dried saffron.

Chemistry

                       Crocin formation
               α–crocin formation mechanism
   Esterification reaction between crocetin and gentiobiose.
    —  β- D-gentiobiose.
    —  Crocetin.
                       Picrocrocin and safranal
   Picrocrocin, with the safranal moiety shaded with saffron colour.
                  Chemical structure of picrocrocin.
    —  Safranal moiety.
    —  β- D-glucopyranose derivative.

   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 ( 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.
    Chemical composition of saffron
      Component         Mass %
    carbohydrates      12.0–15.0
        water          9.0–14.0
    polypeptides       11.0–13.0
      cellulose         4.0–7.0
       lipids           3.0–8.0
      minerals          1.0–1.5
    miscellaneous
   non-nitrogenous       40.0
       Source: Dharmananda 2005
   Proximate analysis of saffron
          Component         Mass %
   Water-soluble components  53.0
     →   Gums                10.0
     →  Pentosans            8.0
     →   Pectins             6.0
     →   Starch              6.0
     →   α–Crocin            2.0
     →  Other carotenoids    1.0
   Lipids                    12.0
     →  Non-volatile oils    6.0
     →  Volatile oils        1.0
   Protein                   12.0
   Inorganic matter ("ash")  6.0
     →  HCl-soluble ash      0.5
   Water                     10.0
   Fibre (crude)             5.0
     Source: Goyns 1999, p. 46

   The bitter glucoside picrocrocin is responsible for saffron's flavour.
   Picrocrocin ( chemical formula: C[16]H[26]O[7]; 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. 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.
   Enlarge
   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.

Mediterranean

   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.
   Enlarge
   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 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.

Asia

   The 17.8 m monolith of Jain God 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.
   Enlarge
   The 17.8 m monolith of Jain God 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 infusions, rice, and baths as a
   curative for battle wounds. Alexander's troops mimicked the practice
   and brought saffron-bathing back to Greece.

   Theories explaining saffron's arrival in South Asia conflict.
   Traditional Kashmiri and Chinese accounts date its arrival anywhere
   between 900–2500 years ago. Meanwhile, historians studying ancient
   Persian records date the arrival to sometime prior to 500 BC,
   attributing it 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 a 7th-century Armenian author, Anania of
   Shirak, observed in his description of China that "unlimited amounts of
   saffron are available there, to the point that if someone went hunting,
   dressed in white, mounted on a white horse and with a white falcon, on
   his return he would be completely covered with yellow" . Indeed,
   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. 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."

Europe

   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.
   Enlarge
   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 centre. 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.

Trade and usage

   Saffron is one of the three essential ingredients in the Spanish paella
   valenciana, and is responsible for its characteristic brilliant yellow
   colouring.
   Enlarge
   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 somewhat bitter. Saffron also contributes a
   luminous yellow-orange colouring to foods. Because of the unusual taste
   and colouring it adds to foods, saffron is widely used in Arab, Central
   Asian, European, Indian, Iranian, Moroccan 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), anti-mutagenic
   (mutation-preventing), immunomodulating, and antioxidant-like
   properties. 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.

            A map showing the primary saffron-producing nations.

    —  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. 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$5,000/pound
   (US$1100–US$11,000 per kilogram). In Western countries, the average
   retail price is $1,000/pound (US$2200 per kilogram). 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.
   Enlarge
   Saffron threads 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 more potent, while
   the most intense varieties tend to be Macedonian Greek, Iranian, and
   Kashmiri Indian in origin. Westerners may face significant obstacles in
   obtaining saffron from Iran and India. For example, the United States
   has banned the import of Iranian saffron; meanwhile, 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. In the U.S.,
   Pennsylvania Dutch saffron — known for its earthy notes — is marketed
   in small quantities.
   Close-up of a single crocus thread (the dried stigma). Actual length is
   about 20mm.
   Enlarge
   Close-up of a single crocus thread (the dried stigma). Actual length is
   about 20mm.

   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.

Grades

   Powdered saffron stored in an airtight glass vial.
   Enlarge
   Powdered saffron stored in an airtight glass vial.
         Minimum saffron colour
     grading standards ( ISO 3632)
   ISO Grade
   (category) Crocin-specific
               absorbance (A[λ]) score
                   (at λ=440 nm)
       I               > 190
       II             150–190
      III             110–150
       IV              80–110
         Source: Tarvand 2005b

   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 Organization for
   Standardization, 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 / I[0]), with A[λ] as
   absorbance ( Beer-Lambert law). It is a measure of a given substance's
   transparency (I / I[0], 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
   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. 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.
   Spanish federal saffron
      grading standards
     Grade     ISO score
     Coupe       > 190
   La Mancha    180–190
      Rio       150–180
   Standard     145–150
    Sierra       < 110
    Source: Tarvand 2005b

   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. Typical
   methods include mixing in extraneous substances like beet, 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. 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.

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