Food coloring, or color additive, is any dye, pigment or substance that imparts color when it is added to food or drink. They come in many forms consisting of liquids, powders and pastes. Food coloring is used both in domestic cooking. Food colorants are used in a variety of non-food applications including cosmetics, home craft projects, medical devices. People associate certain colors with certain flavors, the color of food can influence the perceived flavor in anything from candy to wine. Sometimes the aim is to simulate a color, perceived by the consumer as natural, such as adding red coloring to glacé cherries, but sometimes it is for effect, like the green ketchup that Heinz launched in 1999. Color additives are used in foods for many reasons including: To make food more attractive, appealing and informative Offset color loss due to exposure to light, temperature extremes and storage conditions Correct natural variations in color Enhance colors that occur Provide color to colorless and "fun" foods Allow consumers to identify products on sight, like candy flavors or medicine dosages The addition of colorants to foods is thought to have occurred in Egyptian cities as early as 1500 BC, when candy makers added natural extracts and wine to improve the products' appearance.
During the Middle Ages, the economy in the European countries was based on agriculture, the peasants were accustomed to producing their own food locally or trading within the village communities. Under feudalism, aesthetic aspects were not considered, at least not by the vast majority of the very poor population; this situation changed with urbanization at the beginning of the Modern Age, when trade emerged—especially the import of precious spices and colors. One of the first food laws, created in Augsburg, Germany, in 1531, concerned spices or colorants and required saffron counterfeiters to be burned. With the onset of the industrial revolution, people became dependent on foods produced by others; these new urban dwellers demanded food at low cost. Analytical chemistry was still primitive and regulations few; the adulteration of foods flourished. Heavy metal and other inorganic element-containing compounds turned out to be cheap and suitable to "restore" the color of watered-down milk and other foodstuffs, some more lurid examples being: Red lead and vermillion were used to color cheese and confectionery.
Copper arsenite was used to recolor used tea leaves for resale. It caused two deaths when used to color a dessert in 1860. Sellers at the time offered more than 80 artificial coloring agents, some invented for dyeing textiles, not foods. Thus, with potted meat and sauces taken at breakfast he would consume more or less Armenian bole, red lead, or bisulphuret of mercury. At dinner with his curry or cayenne he would run the chance of a second dose of mercury. Again his tea if mixed or green, he would not escape without the administration of a little Prussian blue... Many color additives had never been tested for toxicity or other adverse effects. Historical records show that injuries deaths, resulted from tainted colorants. In 1851, about 200 people were poisoned in England, 17 of them fatally, directly as a result of eating adulterated lozenges. In 1856, the first synthetic color, was developed by Sir William Henry Perkin and by the turn of the century, unmonitored color additives had spread through Europe and the United States in all sorts of popular foods, including ketchup, mustard and wine.
These were dubbed'coal-tar' colors because the starting materials were obtained from bituminous coal. Many synthesized dyes were easier and less costly to produce and were superior in coloring properties when compared to derived alternatives; some synthetic food colorants are diazo dyes. Diazo dyes are prepared by coupling of a diazonium compound with a second aromatic hydrocarbons; the resulting compounds contain conjugated systems that efficiently absorb light in the visible parts of the spectrum, i.e. they are colored. The attractiveness of the synthetic dyes is that their color and other attributes can be engineered by the design of the specific dyestuff; the color of the dyes can be controlled by selecting the number of azo-groups and various substituents. Yellow shades are achieved by using acetoacetanilide. Red colors are azo compounds; the pair indigo and indigo carmine exhibit the same blue color, but the former is soluble in lipids, the latter is water-soluble because it has been fitted with sulfonate functional groups.
Concerns over food safety led to numerous regulations throughout the world. German food regulations released in 1882 stipulated the exclusion of dangerous minerals such as arsenic, chromium, lead and zinc, which were used as ingredients in colorants. In contrast to today, these first laws followed the principle of a negative listing. In the United States, the Pure Food and Drug Act of 1906 reduced the permitted list of synthetic colors from 700 down to seven; the seven dyes approved were Ponceau 3R, erythrosine, indigotine (F
Painting is the practice of applying paint, color or other medium to a solid surface. The medium is applied to the base with a brush, but other implements, such as knives and airbrushes, can be used; the final work is called a painting. Painting is an important form in the visual arts, bringing in elements such as drawing, composition, narration, or abstraction. Paintings can be naturalistic and representational, abstract, symbolistic, emotive, or political in nature. A portion of the history of painting in both Eastern and Western art is dominated by religious art. Examples of this kind of painting range from artwork depicting mythological figures on pottery, to Biblical scenes Sistine Chapel ceiling, to scenes from the life of Buddha or other images of Eastern religious origin. In art, the term painting describes the result of the action; the support for paintings includes such surfaces as walls, canvas, glass, pottery, leaf and concrete, the painting may incorporate multiple other materials including sand, paper, gold leaf, as well as objects.
Color, made up of hue and value, dispersed over a surface is the essence of painting, just as pitch and rhythm are the essence of music. Color is subjective, but has observable psychological effects, although these can differ from one culture to the next. Black is associated with mourning in the West; some painters, theoreticians and scientists, including Goethe and Newton, have written their own color theory. Moreover, the use of language is only an abstraction for a color equivalent; the word "red", for example, can cover a wide range of variations from the pure red of the visible spectrum of light. There is not a formalized register of different colors in the way that there is agreement on different notes in music, such as F or C♯. For a painter, color is not divided into basic and derived colors. Painters deal with pigments, so "blue" for a painter can be any of the blues: phthalocyanine blue, Prussian blue, Cobalt blue, so on. Psychological and symbolical meanings of color are not speaking, means of painting.
Colors only add to the potential, derived context of meanings, because of this, the perception of a painting is subjective. The analogy with music is quite clear—sound in music is analogous to "light" in painting, "shades" to dynamics, "coloration" is to painting as the specific timbre of musical instruments is to music; these elements do not form a melody of themselves. Modern artists have extended the practice of painting to include, as one example, which began with Cubism and is not painting in the strict sense; some modern painters incorporate different materials such as sand, straw or wood for their texture. Examples of this are the works of Anselm Kiefer. There is a growing community of artists who use computers to "paint" color onto a digital "canvas" using programs such as Adobe Photoshop, Corel Painter, many others; these images can be printed onto traditional canvas. Jean Metzinger's mosaic-like Divisionist technique had its parallel in literature. I make a kind of chromatic versification and for syllables I use strokes which, variable in quantity, cannot differ in dimension without modifying the rhythm of a pictorial phraseology destined to translate the diverse emotions aroused by nature.
Rhythm, for artists such as Piet Mondrian, is important in painting as it is in music. If one defines rhythm as "a pause incorporated into a sequence" there can be rhythm in paintings; these pauses allow creative force to intervene and add new creations—form, coloration. The distribution of form, or any kind of information is of crucial importance in the given work of art, it directly affects the aesthetic value of that work; this is because the aesthetic value is functionality dependent, i.e. the freedom of perception is perceived as beauty. Free flow of energy, in art as well as in other forms of "techne", directly contributes to the aesthetic value. Music was important to the birth of abstract art, since music is abstract by nature—it does not try to represent the exterior world, but expresses in an immediate way the inner feelings of the soul. Wassily Kandinsky used musical terms to identify his works. Kandinsky theorized that "music is the ultimate teacher," and subsequently embarked upon the first seven of his ten Compositions.
Hearing tones and chords as he painted, Kandinsky theorized that, yellow is the color of middle C on a brassy trumpet. In 1871 the young Kandinsky learned to play the cello. Kandinsky's stage design for a performance of Mussorgsky's "Pictures at an Exhibition" illustrates his "synaesthetic" concept of a universal correspondence of forms and musical sounds. Music d
Printing is a process for reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus; the earliest known form of printing as applied to paper was woodblock printing, which appeared in China before 220 AD. Developments in printing technology include the movable type invented by Bi Sheng around 1040 AD and the printing press invented by Johannes Gutenberg in the 15th century; the technology of printing played a key role in the development of the Renaissance and the scientific revolution, laid the material basis for the modern knowledge-based economy and the spread of learning to the masses. Woodblock printing is a technique for printing text, images or patterns, used throughout East Asia, it originated in China in antiquity as a method of printing on textiles and on paper. As a method of printing on cloth, the earliest surviving examples from China date to before 220 A.
D. The earliest surviving woodblock printed fragments are from China, they are of silk printed with flowers in three colours from the Han Dynasty. They are the earliest example of woodblock printing on paper and appeared in the mid-seventh century in China. By the ninth century, printing on paper had taken off, the first extant complete printed book containing its date is the Diamond Sutra of 868. By the tenth century, 400,000 copies of some sutras and pictures were printed, the Confucian classics were in print. A skilled printer could print up to 2,000 double-page sheets per day. Printing spread early to Korea and Japan, which used Chinese logograms, but the technique was used in Turpan and Vietnam using a number of other scripts; this technique spread to Persia and Russia. This technique was transmitted to Europe via the Islamic world, by around 1400 was being used on paper for old master prints and playing cards. However, Arabs never used this to print the Quran because of the limits imposed by Islamic doctrine.
Block printing, called tarsh in Arabic, developed in Arabic Egypt during the ninth and tenth centuries for prayers and amulets. There is some evidence to suggest that these print blocks made from non-wood materials tin, lead, or clay; the techniques employed are uncertain and they appear to have had little influence outside of the Muslim world. Though Europe adopted woodblock printing from the Muslim world for fabric, the technique of metal block printing remained unknown in Europe. Block printing went out of use in Islamic Central Asia after movable type printing was introduced from China. Block printing first came to Europe as a method for printing on cloth, where it was common by 1300. Images printed on cloth for religious purposes could elaborate; when paper became easily available, around 1400, the technique transferred quickly to small woodcut religious images and playing cards printed on paper. These prints produced in large numbers from about 1425 onward. Around the mid-fifteenth-century, block-books, woodcut books with both text and images carved in the same block, emerged as a cheaper alternative to manuscripts and books printed with movable type.
These were all short illustrated works, the bestsellers of the day, repeated in many different block-book versions: the Ars moriendi and the Biblia pauperum were the most common. There is still some controversy among scholars as to whether their introduction preceded or, the majority view, followed the introduction of movable type, with the range of estimated dates being between about 1440 and 1460. Movable type is the system of printing and typography using movable pieces of metal type, made by casting from matrices struck by letterpunches. Movable type allowed for much more flexible processes than block printing. Around 1040, the first known movable type system was created in China by Bi Sheng out of porcelain. Bi Sheng used clay type, which broke but Wang Zhen by 1298 had carved a more durable type from wood, he developed a complex system of revolving tables and number-association with written Chinese characters that made typesetting and printing more efficient. Still, the main method in use there remained woodblock printing, which "proved to be cheaper and more efficient for printing Chinese, with its thousands of characters".
Copper movable type printing originated in China at the beginning of the 12th century. It was used in large-scale printing of paper money issued by the Northern Song dynasty. Movable type spread to Korea during the Goryeo dynasty. Around 1230, Koreans invented a metal type movable printing using bronze; the Jikji, published in 1377, is the earliest known metal printed book. Type-casting was adapted from the method of casting coins; the character was cut in beech wood, pressed into a soft clay to form a mould, bronze poured into the mould, the type was polished. The Korean form of metal movable type was described by the French scholar Henri-Jean Martin as "extremely similar to Gutenberg's". Eastern metal movable type was spread to Europe between the late 14th century and the early 15th century. Around 1450, Johannes Gutenberg introduced the first movable type printing system in Europe, he advanced innovations in casting type based on a matrix and hand mould, adaptations to the screw-press, the use of an oil-based ink, the creation of a softer and more absorbent paper.
Gutenberg was the first to create his type pieces from an alloy of lead, antimony and bismuth – the same components still used today. Johannes Gutenberg started work on his printing press around 1436, in partnership with Andreas Dritzeh
Paint is any pigmented liquid, liquefiable, or mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most used to protect, color, or provide texture to objects. Paint can be made or purchased in many colors—and in many different types, such as watercolor, etc. Paint is stored and applied as a liquid, but most types dry into a solid. In 2003 and 2004, South African archeologists reported finds in Blombos Cave of a 100,000-year-old human-made ochre-based mixture that could have been used like paint. Further excavation in the same cave resulted in the 2011 report of a complete toolkit for grinding pigments and making a primitive paint-like substance. Cave paintings drawn with red or yellow ochre, manganese oxide, charcoal may have been made by early Homo sapiens as long as 40,000 years ago. Ancient colored walls at Dendera, which were exposed for years to the elements, still possess their brilliant color, as vivid as when they were painted about 2,000 years ago.
The Egyptians mixed their colors with a gummy substance, applied them separately from each other without any blending or mixture. They appear to have used six colors: white, blue, red and green, they first covered the area with white traced the design in black, leaving out the lights of the ground color. They used minium for red, of a dark tinge. Pliny mentions some painted ceilings in his day in the town of Ardea, done prior to the foundation of Rome, he expresses great surprise and admiration after the lapse of so many centuries. Paint was made with the yolk of eggs and therefore, the substance would harden and adhere to the surface it was applied to. Pigment was made from plants and different soils. Most paints used either water as a base. A still extant example of 17th-century house oil painting is Ham House in Surrey, where a primer was used along with several undercoats and an elaborate decorative overcoat; the process was done by hand by the painters and exposed them to lead poisoning due to the white-lead powder.
In 1718, Marshall Smith invented Engine for the Grinding of Colours" in England. It is not known how it operated, but it was a device that increased the efficiency of pigment grinding dramatically. Soon, a company called Emerton and Manby was advertising exceptionally low-priced paints, ground with labour-saving technology: One Pound of Colour ground in a Horse-Mill will paint twelve Yards of Work, whereas Colour ground any other Way, will not do half that Quantity. By the proper onset of the Industrial Revolution, paint was being ground in steam-powered mills and an alternative to lead-based pigments was found in a white derivative of zinc oxide. Interior house painting became the norm as the 19th century progressed, both for decorative reasons and because the paint was effective in preventing the walls rotting from damp. Linseed oil was increasingly used as an inexpensive binder. In 1866, Sherwin-Williams in the United States opened as a large paint-maker and invented a paint that could be used from the tin without preparation.
It was not until the stimulus of World War II created a shortage of linseed oil in the supply market that artificial resins, or alkyds, were invented. Cheap and easy to make, they held the color well and lasted for a long time; the vehicle is composed of the binder. In this case, once the paint has dried or cured nearly all of the diluent has evaporated and only the binder is left on the coated surface. Thus, an important quantity in coatings formulation is the "vehicle solids", sometimes called the "resin solids" of the formula; this is the proportion of the wet coating weight, binder, i.e. the polymer backbone of the film that will remain after drying or curing is complete. The binder is the film-forming component of paint, it is the only component, always present among all the various types of formulations. Many binders must be thinned; the type of thinner, if present, varies with the binder. The binder imparts properties such as gloss, durability and toughness. Binders include synthetic or natural resins such as alkyds, vinyl-acrylics, vinyl acetate/ethylene, polyesters, melamine resins, silanes or siloxanes or oils.
Binders can be categorized according to the mechanisms for film formation. Thermoplastic mechanisms include coalescence. Drying refers to simple evaporation of the thinner to leave a coherent film behind. Coalescence refers to a mechanism that involves drying followed by actual interpenetration and fusion of discrete particles. Thermoplastic film-forming mechanisms are sometimes described as "thermoplastic cure" but, a misnomer because no chemical curing reactions are required to knit the film. Thermosetting mechanisms, on the other hand, are true curing mechanism that involve chemical reaction among the polymers that make up the binder. Thermoplastic mechanisms: Some films are formed by simple cooling of the binder. For example, encaustic or wax paints are liquid when warm, harden upon cooling. In many cases, they liquify if reheated. Paints that dry by solvent evaporation and contain the solid binder dissolved in a solvent are known as lacquers. A solid film forms; because no chemical crosslinking is involved, the film can re-dissolve in solvent.
Ink is a liquid or paste that contains pigments or dyes and is used to color a surface to produce an image, text, or design. Ink is used for writing with a pen, brush, or quill. Thicker inks, in paste form, are used extensively in lithographic printing. Ink can be a complex medium, composed of solvents, dyes, lubricants, surfactants, particulate matter and other materials; the components of inks serve many purposes. In 2011 worldwide consumption of printing inks generated revenues of more than 20 billion US dollars. Demand by traditional print media is shrinking, on the other hand more and more printing inks are consumed for packagings. Many ancient cultures around the world have independently discovered and formulated inks for the purposes of writing and drawing; the knowledge of the inks, their recipes and the techniques for their production comes from archaeological analysis or from written text itself. Ink was used in Ancient Egypt for writing and drawing on papyrus from at least the 26th century BC.
The history of Chinese inks can be traced to the 23rd century BC, with the utilization of natural plant and mineral inks based on such materials as graphite that were ground with water and applied with ink brushes. Evidence for the earliest Chinese inks, similar to modern inksticks, is around 256 BC in the end of the Warring States period and produced from soot and animal glue; the best inks for drawing or painting on paper or silk are produced from the resin of the pine tree. They must be between 100 years old; the Chinese inkstick is produced with a fish glue, whereas Japanese glue is from stag. The process of making India ink was known in China as early as the middle of the 3rd millennium BC, during Neolithic China. India ink was first invented in China, although the source of materials to make the carbon pigment in India ink was often traded from India, thus the term India ink was coined; the traditional Chinese method of making the ink was to grind a mixture of hide glue, carbon black and bone black pigment with a pestle and mortar pouring it into a ceramic dish where it could dry.
To use the dry mixture, a wet brush would be applied. The manufacture of India ink was well-established by the Cao Wei Dynasty. Indian documents written in Kharosthi with ink have been unearthed in Chinese Turkestan; the practice of writing with ink and a sharp pointed needle was common in early South India. Several Buddhist and Jain sutras in India were compiled in ink. In ancient Rome, atramentum was used; the recipe was used for centuries. Iron salts, such as ferrous sulfate, were mixed with tannin from a thickener; when first put to paper, this ink is bluish-black. Over time it fades to a dull brown. Scribes in medieval Europe wrote principally on vellum. One 12th century ink recipe called for hawthorn branches to be left to dry; the bark was pounded from the branches and soaked in water for eight days. The water was boiled until it turned black. Wine was added during boiling; the ink was hung in the sun. Once dried, the mixture was mixed with iron salt over a fire to make the final ink; the reservoir pen, which may have been the first fountain pen, dates back to 953, when Ma'ād al-Mu'izz, the caliph of Egypt, demanded a pen that would not stain his hands or clothes, was provided with a pen that held ink in a reservoir.
In the 15th century, a new type of ink had to be developed in Europe for the printing press by Johannes Gutenberg. According to Martyn Lyons in his book Books: A Living History, Gutenberg's dye was indelible, oil-based, made from the soot of lamps mixed with varnish and egg white. Two types of ink were prevalent at the time: the Greek and Roman writing ink and the 12th century variety composed of ferrous sulfate, gall and water. Neither of these handwriting inks could adhere to printing surfaces without creating blurs. An oily, varnish-like ink made of soot and walnut oil was created for the printing press. Ink formulas vary, but involve two components: Colorants Vehicles Inks fall into four classes: Aqueous Liquid Paste Powder Pigment inks are used more than dyes because they are more color-fast, but they are more expensive, less consistent in color, have less of a color range than dyes. Pigments are solid, opaque particles suspended in ink to provide color. Pigment molecules link together in crystalline structures that are 0.1–2 µm in size and comprise 5–30 percent of the ink volume.
Qualities such as hue and lightness vary depending on the source and type of pigment. Dye-based inks are much stronger than pigment-based inks and can produce much more color of a given density per unit of mass. However, because dyes are dissolved in the liquid phase, they have a tendency to soak into paper, making the ink less efficient and allowing the ink to bleed at the edges of an image. To circumvent this problem, dye-based inks are made with solvents that dry or are used with quick-drying methods of printing, such as blowing hot air on the fresh print. Other methods include more specialized paper coatings; the latter is suited to inks us
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence and other forms of luminescence, in which a material emits light. Most materials selectively absorb certain wavelengths of light. Materials that humans have chosen and developed for use as pigments have special properties that make them useful for coloring other materials. A pigment must have a high tinting strength relative to the materials colors, it must be stable in solid form at ambient temperatures. For industrial applications, as well as in the arts and stability are desirable properties. Pigments that are not permanent are called fugitive. Fugitive pigments fade over time, or with exposure to light, while some blacken. Pigments are used for coloring paint, plastic, cosmetics and other materials. Most pigments used in manufacturing and the visual arts are dry colorants ground into a fine powder. For use in paint, this powder is added to a binder, a neutral or colorless material that suspends the pigment and gives the paint its adhesion.
A distinction is made between a pigment, insoluble in its vehicle, a dye, which either is itself a liquid or is soluble in its vehicle. A colorant can act as either a dye depending on the vehicle involved. In some cases, a pigment can be manufactured from a dye by precipitating a soluble dye with a metallic salt; the resulting pigment is called a lake pigment. The term biological pigment is used for all colored substances independent of their solubility. In 2006, around 7.4 million tons of inorganic and special pigments were marketed worldwide. Asia has the highest rate on a quantity basis followed by North America; the global demand on pigments was US$20.5 billion in 2009. Pigments appear colored because they selectively reflect and absorb certain wavelengths of visible light. White light is a equal mixture of the entire spectrum of visible light with a wavelength in a range from about 375 or 400 nanometers to about 760 or 780 nm; when this light encounters a pigment, parts of the spectrum are absorbed by the pigment.
Organic pigments such as diazo or phthalocyanine compounds feature conjugated systems of double bonds. Some inorganic pigments, such as vermilion or cadmium yellow, absorb light by transferring an electron from the negative ion to the positive ion; the other wavelengths or parts of the spectrum are scattered. The new reflected. Pigments, unlike fluorescent or phosphorescent substances, can only subtract wavelengths from the source light, never add new ones; the appearance of pigments is intimately connected to the color of the source light. Sunlight has a high color temperature and a uniform spectrum and is considered a standard for white light, while artificial light sources tend to have strong peaks in parts of their spectra. Viewed under different lights, pigments will appear different colors. Color spaces used to represent colors. Lab color measurements, unless otherwise noted, assume that the measurement was taken under a D65 light source, or "Daylight 6500 K", the color temperature of sunlight.
Other properties of a color, such as its saturation or lightness, may be determined by the other substances that accompany pigments. Binders and fillers added to pure pigment chemicals have their own reflection and absorption patterns, which can affect the final spectrum. For example, in pigment/binder mixtures, individual rays of light may not encounter pigment molecules and may be reflected unchanged; these stray rays of source light make. Pure pigment allows little white light to escape, producing a saturated color, while a small quantity of pigment mixed with a lot of white binder will appear unsaturated and pale due to incident white light escaping unchanged. Occurring pigments such as ochres and iron oxides have been used as colorants since prehistoric times. Archaeologists have uncovered evidence that early humans used paint for aesthetic purposes such as body decoration. Pigments and paint grinding equipment believed to be between 350,000 and 400,000 years old have been reported in a cave at Twin Rivers, near Lusaka, Zambia.
Before the Industrial Revolution, the range of color available for art and decorative uses was technologically limited. Most of the pigments in use were pigments of biological origin. Pigments from unusual sources such as botanical materials, animal waste and mollusks were harvested and traded over long distances; some colors were impossible to obtain, given the range of pigments that were available. Blue and purple came to be associated with royalty because of their rarity. Biological pigments were difficult to acquire, the details of their production were kept secret by the manufacturers. Tyrian Purple is a pigment made from the mucus of one of several species of Murex snail. Production of Tyrian Purple for use as a fabric dye began as early as 1200 BCE by the Phoenicians, was continued by the Greeks and Romans until 1453 CE, with the fall of Constantinople; the pigment was expensive and complex to produce, items colored with it became associated with power and wealth. Greek historian Theopompus, writing in the 4th century BCE, reported that "purple for dyes fetched its weight in silver at Colophon."Mineral pigments were traded over long distances.
The only w
Biological pigments known as pigments or biochromes, are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments. Many biological structures, such as skin, feathers and hair contain pigments such as melanin in specialized cells called chromatophores. Pigment color differs from structural color in that it is the same for all viewing angles, whereas structural color is the result of selective reflection or iridescence because of multilayer structures. For example, butterfly wings contain structural color, although many butterflies have cells that contain pigment as well. See conjugated systems for electron bond chemistry that causes these molecules to have pigment. Heme/porphyrin-based: chlorophyll, hemocyanin, myoglobin Light-emitting: luciferin Carotenoids: Hematochromes Carotenes: alpha and beta carotene, rhodopsin Xanthophylls: canthaxanthin, lutein Proteinaceous: phytochrome, phycobiliproteins Polyene enolates: a class of red pigments unique to parrots Other: melanin, flavonoids The primary function of pigments in plants is photosynthesis, which uses the green pigment chlorophyll and several colorful pigments that absorb as much light energy as possible.
Other functions of pigments in plants include attracting insects to flowers to encourage pollination. Plant pigments include many molecules, such as porphyrins, carotenoids and betalains. All biological pigments selectively absorb certain wavelengths of light while reflecting others; the principal pigments responsible are: Chlorophyll is the primary pigment in plants. It is the presence and relative abundance of chlorophyll. All land plants and green algae possess two forms of this pigment: chlorophyll a and chlorophyll b. Kelps and other photosynthetic heterokonts contain chlorophyll c instead of b, while red algae possess only chlorophyll a. All chlorophylls serve as the primary means plants use to intercept light in order to fuel photosynthesis. Carotenoids are red, orange, or yellow tetraterpenoids. During the process of photosynthesis, they have functions in light-harvesting, in photoprotection, serve as protein structural elements. In higher plants, they serve as precursors to the plant hormone abscisic acid.
Plants, in general, contain six ubiquitous carotenoids: neoxanthin, antheraxanthin, lutein and β-carotene. Lutein is a yellow pigment found in fruits and vegetables and is the most abundant carotenoid in plants. Lycopene is the red pigment responsible for the color of tomatoes. Other less common carotenoids in plants include lutein epoxide and alpha carotene. In cyanobacteria, many other carotenoids exist such as canthaxanthin, myxoxanthophyll and echinenone. Algal phototrophs such as dinoflagellates use peridinin as a light harvesting pigment. While carotenoids can be found complexed within chlorophyll-binding proteins such as the photosynthetic reaction centers and light-harvesting complexes, they are found within dedicated carotenoid proteins such as the orange carotenoid protein of cyanobacteria. Anthocyanins are water-soluble flavonoid pigments that appear red to blue, according to pH, they occur in all tissues of higher plants, providing color in leaves, plant stem, roots and fruits, though not always in sufficient quantities to be noticeable.
Anthocyanins are most visible in the petals of flowers of many species. Betalains are yellow pigments. Like anthocyanins they are water-soluble, but unlike anthocyanins they are synthesized from tyrosine; this class of pigments is found only in the Caryophyllales, never co-occur in plants with anthocyanins. Betalains are responsible for the deep red color of beets. A noticeable manifestation of pigmentation in plants is seen with autumn leaf color, a phenomenon that affects the green leaves of many deciduous trees and shrubs whereby they take on, during a few weeks in the autumn season, various shades of red, yellow and brown. Chlorophylls degrade into colorless tetrapyrroles known as nonfluorescent chlorophyll catabolites; as the predominant chlorophylls degrade, the hidden pigments of yellow xanthophylls and orange beta-carotene are revealed. These pigments are present throughout the year, but the red pigments, the anthocyanins, are synthesized de novo once half of chlorophyll has been degraded.
The amino acids released from degradation of light harvesting complexes are stored all winter in the tree's roots, branches and trunk until next spring when they are recycled to re‑leaf the tree. Pigmentation is used by many animals for protection, by means of camouflage, mimicry, or warning coloration; some animals including fish and cephalopods use pigmented chromatophores to provide camouflage that varies to match the background. Pigmentation is used in signalling between animals, such as in reproductive behavior. For example, some cephalopods use their chromatophores to communicate; the photopigment rhodopsin intercepts light as the first step in the perception of light. Skin pigments such as melanin may protect tissues from sunburn by ultraviolet radiation. However, some biological structures in animals, such as heme groups that