Cochineal

Opuntia species, known commonly as prickly pears, were first brought to Australia in an attempt to start a cochineal dye industry in 1788. Captain Arthur Phillip collected a number of cochineal-infested plants from Brazil on his way to establish the first European settlement at Botany Bay, part of which is now Sydney, New South Wales. At that time, Spain and Portugal had a worldwide cochineal dye monopoly via their New World colonial sources, and the British desired a source under their own control, as the dye was important to their clothing and garment industries; it was used to color the British soldiers' red coats, for example.[15] The attempt was a failure in two ways: the Brazilian cochineal insects soon died off, but the cactus thrived, eventually overrunning about 100,000 sq mi (259,000 km²) of eastern Australia.[16] The cacti were eventually brought under control in the 1920s by the deliberate introduction of a South American moth, Cactoblastis cactorum, the larvae of which feed on the cactus.[16]

The nopal pear has been traditionally eaten in parts of northern Ethiopia, where it is utilized more than cultivated. Carmine cochineal was introduced into northern Ethiopia early in the 2000s to be cultivated among farming communities. Foodsafe exported 2000 tons of dried carmine cochineal over 3 years.

A conflict of interest among communities led to closure of the cochineal business in Ethiopia, but the insect spread and became a pest. Cochineal infestation continued to expand after the cochineal business had ended. Control measures were unsuccessful and by 2014 about 16,000 hectares (62 sq mi) of cactus land had become infested with cochineal.[17]

Wool dyed with cochineal

External video
“Cochinea Red Dye - The Use of Cochineal Beetles as Natural Fabric Dye in Chinchero, Peru”, Quechua woman artisan

Cochineal dyes are one of three groups of red insect dyes, all of which are anthraquinone derivatives. The major color components in their respective chemical structures are carminic acid (in cochineal dyes), kermesic acid (in kermes dye) and laccaic acids (in lac dye).[18]

Carminic acid is extracted from the female cochineal insects and is treated to produce carmine, which can yield shades of red such as crimson and scarlet.[19] The dried body of the female insect is 14–26% carminic acid.[20]

Steps in the cochineal harvest in Oaxaca, public mural by Arturo Garcia Bustos, Mexico

Workers collect the female cochineal insects from their host plants.[5] The insects are processed by immersion in hot water or by exposure to sunlight, steam, or the heat of an oven. Each method produces a different color that results in the varied appearance of commercial cochineal.[21] The insects must be dried to about 30% of their original body weight before they can be stored without decaying.[14] It takes about 70,000 insects to make one pound of cochineal dye.[5]

The two principal forms of cochineal dye are cochineal extract, a coloring made from the raw dried and pulverised bodies of insects, and carmine, a more purified coloring made from the cochineal. To prepare carmine, the powdered insect bodies are boiled in ammonia or a sodium carbonate solution, the insoluble matter is removed by filtering, and alum is added to the clear salt solution of carminic acid to precipitate the red aluminium salt. Purity of color is ensured by the absence of iron. Stannous chloride, citric acid, borax, or gelatin may be added to regulate the formation of the precipitate. For shades of purple, lime is added to the alum.[22][23]

Traditionally, cochineal was used for coloring fabrics. Cochineal dye was used by the Aztec and Maya peoples of North and Central America as early as the second century BC.[24]^: 12[25] Inhabitants of Peru have been producing cochineal dyes for textiles since early in the Middle Horizon period (600–1000 CE).[26] Cochineal dye was extensively used in the Pre-Columbian era, often for ceremonial textiles and those worn by rulers.[24]^: 12–25

The dye bonds best with animal fibers rather than plant fibers and was most effective for dying wool from alpacas and other Camelidae, rabbit fur, and feathers. It was also used on cottons and plant-based fabrics, to less effect. Some examples of early cloth have survived in extremely dry areas in Peru. In addition, the use of cochineal is literally illustrated in drawings on codices and maps. Production of cochineal dyes became well-developed under Nazca culture, and beautiful examples of woven cloth colored by cochineal remain from Moche and Wari culture.[24]^: 12–25[27]

• 
  Carrying Cloth (Peru), c. 600–1000 AD
• 
  Moche-Wari Yoke from a Tunic, c. 800-1200 AD
• 
  Pre-Columbian textile from Peru, c. 800-1300 AD[27]
• 
  Tapestry shirt fragment, Peru, Chancay, c. 1000-1470 AD

Cochineal's importance is also indicated by its prominence in tribute lists such as the Matrícula de Tributos.[24]^: 12–20 Eleven cities conquered by Moctezuma II in the 15th century paid a yearly tribute of 2000 decorated cotton blankets and 40 bags of cochineal dye each.[22]

Prior to the Spanish invasion, Aztecs also used cochineal pigments in their manuscripts. The 16th century Florentine Codex contains a variety of illustrations with multiple variations of the red pigments. Specifically in the case of achiotl (light red), technical analysis of the paint reveals multiple layers of the pigment although the layers of the pigment is not visible to the naked eye. Therefore, it proves that the process of applying multiple layers is more significant in comparison to the actual color itself. Furthermore, the process of layering the various hues of the same pigment on top of each other enabled the Aztec artists to create variations in the intensity of the subject matter. A bolder application of pigment draws the viewer's eye to the subject matter which commands attention and suggests a power of the viewer. A weaker application of pigment commands less attention and has less power. This would suggest that the Aztec associated the intensity of pigments with the idea of power and life.[28]

Pigments are insoluble finely ground particles which are mixed with a liquid to make a paint.[29] To be useful as a pigment, a substance should be insoluble in the vehicle with which it is mixed, in contrast to a dye which is soluble.[30] The activity of carmines can vary widely depending on their preparation and composition: they tend to be unstable and can vary in solubility depending on pH.[31][32]

Recipes for artists' use of crimson appear in many early painting and alchemical handbooks throughout the Middle Ages. Red lake pigments were known to be particularly unstable as early as the 1400s.[33][34] When cochineal lakes were introduced in Europe, artists soon found that they were not light-fast. The paint turns brown and fades in sunlight, although it is somewhat more permanent if mixed with oil rather than water color.[35] As a result, carmine's use as a pigment was discouraged: its primary use was as a dye rather than in paints.[33][34]

“Beautiful and rich as are the colours prepared from cochineal, not one of them should ever find a place upon the palette of the artist. They all become brownish and ultimately almost disappear after a short exposure to sunlight or the more prolonged attack of strong diffused daylight”, Arthur Herbert Church[33][36]

In Europe, there was no comparable red dye or pigment. The closest color was Kermes (technically, crimson), one of the oldest organic pigments. Its key ingredient, kermesic acid, was also extracted from an insect, Kermes vermilio, which lives on Quercus coccifera oaks native to the Near East, and the European side of the Mediterranean Basin. Kermes was used as a dye and a laked pigment in ancient Egypt, Greece, Armenia and the Near East.[37]

The Spanish conquest of the Aztec Empire in the 16th century introduced new colors to peoples on both sides of the Atlantic. The Spanish were quick to exploit the vibrant, intense color of cochineal for new trade opportunities. Carmine attained great status and value in Europe.[38][39]

During the colonial period, with the introduction of sheep to Latin America, the use of cochineal increased. It provided the most intense color and it set more firmly on woolen garments compared to clothes made of materials of pre-Hispanic origin such as cotton or agave and yucca fibers. In general, cochineal is more successful on protein-based animal fibres (including silk) than plant-based material.[39]

Once the European market discovered the qualities of this product (grana fina), the demand for it increased dramatically.[39][38] Carmine became the region's second-most-valuable export next to silver.[40] The dyestuff was used throughout Europe and was so highly prized, its price was regularly quoted on the London and Amsterdam Commodity Exchanges (with the latter one beginning to record it in 1589).[38] By the 17th century cochineal was a commodity traded as far away as India.[39]

The production and the use of luxury colors and textiles were regulated in countries such as Spain and Italy.[24]^: 45–46 Dyestuffs produced from the cochineal insect were used for dyeing the clothes of kings, nobles, and the clergy.[39] In 1454, Pope Paul II officially changed the color of the robes worn by Catholic cardinals from "Cardinal's purple" to vibrant red. By 1558, their red robes would have been created with American cochineal.[24]^: 45 By the 1600s, cochineal also gave the English "Redcoats" their distinctive officers' uniforms.[24]^: 28–29 Carmine became strong competition for other colorants such as madder root, kermes, Polish cochineal, Armenian cochineal, brazilwood, and Tyrian purple.[41] It became the most important insect dye used in the production of hand-woven oriental rugs, almost completely displacing lac.[39] It was also used for handicrafts, and tapestries.[42]

Moctezuma dead in the waters of the grand canal

Spanish influence also changed the way in which Aztecs used pigments, particularly in their manuscripts. The use of cochineal in manuscripts was replaced by Spanish dyes like minium and alizarin crimson.[28] The image of Moctezuma's death (seen to the right) uses both indigenous and Spanish pigments, and is therefore representative of the transition and influence between cultures.

During the colonial period in Latin America, many indigenous communities produced cochineal under a type of contract known as Repartimiento de Mercancías. This was a type of ”contract forwarding” agreement, in which a trader lent money to producers in advance, with a "call option" to buy the product once it was harvested. Communities with a history of cochineal production and export have been found to have lower poverty rates and higher female literacy, but also smaller indigenous populations.[43]

In 1777, French botanist Nicolas-Joseph Thiéry de Menonville, presenting himself as a botanizing physician, smuggled the insects and pads of the Opuntia cactus to Saint Domingue. This particular collection failed to thrive and ultimately died out, leaving the Mexican monopoly intact.[44] After the Mexican War of Independence in 1810–1821, the Mexican monopoly on cochineal came to an end. Large-scale production of cochineal emerged, especially in Guatemala and the Canary Islands; it was also cultivated in Spain and North Africa.[39]

The demand for cochineal fell sharply in the middle of the 19th century, with the appearance of artificial dyes such as alizarin crimson. This caused a significant financial shock in Spain as a major industry almost ceased to exist.[40] The delicate manual labour required for the breeding of the insect could not compete with the modern methods of the new industry, and even less so with the lowering of production costs. The "tuna blood" dye (from the Mexican name for the Opuntia fruit) stopped being used and trade in cochineal almost totally disappeared in the course of the 20th century. For a time, the breeding of cochineal was done mainly for the purposes of maintaining the tradition rather than to satisfy any sort of demand.[42]

However, the product has become commercially valuable again.[19] One reason for the increasing interest in natural dyes is consumer concern over the possibility that some commercial synthetic red dyes and food colorings may be carcinogenic.[45] Being natural is not a guarantee of safety,[46] but studies show that cochineal is neither carcinogenic nor toxic. Cochineal does, however, have a slight potential to trigger an allergic reaction.[47][48]

Cochineal use in histology: Carmine staining of a monogenean (parasitic worm)

Cochineal continues to be used as a fabric dye, a cosmetics dye and as a food coloring.[5] It is also used in histology as a preparatory stain for the examination of tissues and carbohydrates.[49]

As of 2005, Peru produced 200 tons of cochineal dye per year and the Canary Islands produced 20 tons per year.[19][14] Chile and Mexico also export cochineal.[4] France is believed to be the world's largest importer, and Japan and Italy also import the insect. Much of these imports are processed and re-exported to other developed economies.[14] As of 2005, the market price of cochineal was between US$50 and 80 per kilogram,[11] while synthetic raw food dyes are available at prices as low as $10–20 per kilogram.[50]

Natural carmine dye used in food and cosmetics can render the product unacceptable to vegetarian or vegan consumers. Many Muslims consider carmine-containing food forbidden (haraam) because the dye is extracted from insects and all insects except the locust are haram in Islam.[51] Jews also avoid food containing this additive, though it is not treif, and some authorities allow its use because the insect is dried and reduced to powder.[52]

Cochineal is one of the few water-soluble colorants to resist degradation with time. It is one of the most light- and heat-stable and oxidation-resistant of all the natural organic colorants and is even more stable than many synthetic food colors.[53] The water-soluble form is used in alcoholic drinks with calcium carmine; the insoluble form is used in a wide variety of products. Together with ammonium carmine, they can be found in meat, sausages, processed poultry products (meat products cannot be colored in the United States unless they are labeled as such), surimi, marinades, alcoholic drinks, bakery products and toppings, cookies, desserts, icings, pie fillings, jams, preserves, gelatin desserts, juice beverages, varieties of cheddar cheese and other dairy products, sauces, and sweets.[53]

Carmine is considered safe enough for cosmetic use in the eye area.[54] A significant proportion of the insoluble carmine pigment produced is used in the cosmetics industry for hair- and skin-care products, lipsticks, face powders, rouges, and blushes.[53] A bright red dye and the stain carmine used in microbiology is often made from the carmine extract, too.[9] The pharmaceutical industry uses cochineal to color pills and ointments.[14]

Cochineal-colored wool and cotton continue to be important materials for Mexican folk art and crafts.[55][24] Some towns in the Mexican state of Oaxaca continue to follow traditional practices of producing and using cochineal when making handmade textiles.[56] In Guatemala, Heifer International has partnered with local women who wished to reintroduce traditional artisanal practices of cochineal production and use.[57]

Because it has a complicated structure involving multiple chemical groups, it is very difficult to create a synthetic molecule for cochineal. In 1991, carminic acid was first synthesized in the laboratory by organic chemists.[58] In 2018, researchers genetically engineered the microbe Aspergillus nidulans to produce carminic acid.[5][59]

In spite of the widespread use of carmine-based dyes in food and cosmetic products, a small number of people have been found to experience occupational asthma, food allergy and cosmetic allergies (such as allergic rhinitis and cheilitis), IgE-mediated respiratory hypersensitivity, and in rare cases anaphylactic shock.[60][61][62] In 2009 the FDA ruled that labels of cosmetics and food that include cochineal extract must include that information on their labels (under the name "cochineal extract" or "carmine").[63][64] In 2006 the FDA stated it found no evidence of a "significant hazard" to the general population.[65] In the EU authorities list carmine as additive E 120 in the list of EU-approved food additives.[66] An artificial, non-allergenic cochineal dye is labeled E 124.[60]