Pigments

Brief about Pigments and their sources

1. PIGMENTS D.SRENUJA 15FT1D7804

2. Color -To denote the human eye’s perception of colored materials, part of the electromagnetic spectrum visible to the human eye and generally regarded as lying between 400 - 700 nm i.e . red, blue, or green . Together with flavor and texture, color plays an important role in food acceptability . Color is mainly a matter of transmission of light for clear liquid foods, such as oils and beverages . Color may provide an indication of chemical changes in a food, such as browning and caramelization.

3. Pigment : A pigment is a material that changes the color of as the result of wavelength-selective absorption . They are the natural substances in cells and tissues of plants and animals. Dyes are any substances that lend to color to materials and are water soluble. Dyes are food grade , certified by U.S. F.D.A. Lakes are dyes extended on a substratum and they are oil dispersible.

4. Plant Pigments : Normal constituents of cells or tissues,that impart color. It has other properties, i.e. energy receptor, carriers of O2, protects against radiation. Chlorophylls Carotenoids Flavonoids Anthocyanins Tannins Betalains Quinones Xanthones

5. Chlorophylls: They are major light harvesting pigments in green plants, algae and photosynthetic bacteria . They are Mg complexes derived from Porphin.

6. α β γ δ α β γ δ Phorbin Pyrrole C-atoms on the periphery of the Porphin structure are numbered 1 to 8. Carbon atoms of the bridging carbons are designated as α,β,γ and δ. Substituted porphins are named as porphyrins, it is macro cyclic tetra pyrrole pigment in which the pyrrole rings are formed by the methane bridges , double bonds forms closed conjugated loop.. Phorbin is considered to be the nucleus of all chlorophyll and is formed by the addition of a fifth iso-cyclic ring to Porphin. Porphin is fully unsaturated macrocyclic structure that contains 4 pyrrole rings linked by single bridging carbons .

7. There are 6 different types of Chlorophyll pigment that have been identified by famous chemists including Richard Willstätter, HansFischer , Robert Burns Woodward and Ian Fleming. Their structures are based on a chlorin ring at the center of which is a magnesium ion. The structure can have different side chains depending on the type of Chlorophyll. Chlorophyll a: Chlorophyll a is the most widely occurring and universal type of Chlorophyll . It is found in plants, algae and many other aquatic organisms . Chlorophyll a is molecular structure consists of a chlorin ring with Mg center. It absorbs light from red, blue and violet wavelengths and gets its color by reflecting green.

8. B. Chlorophyll b: It is a type of Chlorophyll that is mostly found in plants. It aids the process of photosynthesis, by absorbing light energy. A nd primarily it absorbs blue light . The pigment itself is yellow in color. Similar to Chlorophyll a , Chlorophyll b's molecular structure has a 4-ions Nitrogen ring with Mg center , with side chains hydrocarbon trail.

9. Structures of chlorophyll a and b Chemical Group: Tetrapyrroles

10. C . Chlorophyll c1: Chlorophyll c1 works in conjunction with Chlorophyll a to absorb light and aid photosynthesis. This type of Chlorophyll has a brownish or golden color and is found mostly in marine algae. The molecular structure of Chlorophyll c1consists of a Chlorin ring but does not have a tail. D . Chlorophyll c2: Similar to Chlorophyll c1, Chlorophyll c2 is mostly found in marine and freshwater algae. Its molecular structure has a 4 ion Nitrogen ring and Mg center but does not have a tail.

11. Chlorophyll C1 and C2

12. E. Chlorophyll d: Identified comparatively recently 1996, Chlorophyll d is a type of Chlorophyll that absorbs light which is in the extreme red end of the light spectrum. The natural occurrence of Chlorophyll d is found only in Acaryochloris marina , a type of Cyanobacteria . F. Chlorophyll f: Chlorophyll f absorbs infrared light , from most extreme end of red spectrum . Chlorophyll f occurrence in nature is very less,except i.e.,found in Cyanobacteria. Chlorophyll f exact function in the process of photosynthesis is also uncertain.

13. Chlorophyll is registered as a food additive (colorant), and its E number is E140. Chefs use chlorophyll to color a variety of foods and beverages green, such as pasta products. Chlorophyll is not soluble in water, and it is first mixed with a small quantity of vegetable oil to obtain the desired solution .

14. Chemistry: They are associated with carotenoids ,lipids and lipo-proteins. Weak linkages(non-covalent bonds) exist between these molecules. The bonds are easily broken, hence chlorophylls can be extracted by macerating plant tissue in organic solvents .

15. C . Carotenoids: Occurrence: Carotenoids are lipid-soluble, yellow–orange–red pigments found in the chloroplasts and chromoplasts in plants and animals. Animals cannot synthesize carotenoids, so their presence is due to dietary intake. Carotenoids are the most complex class of natural food colorants with around 750 different structures identified. Carotenoids can be divided into carotenes containing only carbon and hydrogen.

16. Chemical Group : Tetraterpenoids Carotenoids has two structural groups , they are hydrocarbons carotenes and oxygenated xanthophyll. This xanthophyll consists hydroxyl , epoxy , aldehyde and ketone groups. The basic carotenoid structural backbone consists of isoprene units linked by covalently in either a head-to-tail or a tail-to-tail fashion.

17. Lycopene: Being a precursor in the biosynthesis of β-carotene, lycopene can be expected to be found in plants. The best-known sources of lycopene are tomatoes, watermelon, guava, and pink grapefruit. In tomato oleoresin also contains appreciable amounts of β-carotene, phytoene, and phytofluene Lutein: Lutein is also a very common carotenoid. The name is derived from the Latin word for yellow. Lutein is made from Aztec marigold also contains some zeaxanthin (typically less than 10 %). Containing only 10 conjugated double bonds, lutein is more yellowish-green.

18. Chemistry: Their color is masked by chlorophyll in photosynthetic tissues, but in late stages of plant development these pigments contribute to the bright colors of many flowers and fruits and the carrot root. A good source of plant carotenes is oil palm (Elaeis guineensis) fruits, the mesocarp of which contains an oil rich in carotenes.

19. Flavonoids: Flavonoids or bioflavonoids (from the Latin word flavus meaning yellow, their color in nature) are a class of plant secondary metabolites. Over 5000 naturally occurring flavonoids have been characterized from various plants. They have been classified according to their chemical structure, and are usually subdivided into the following subgroups Sub-groups: Anthoxanthins (Flavone & Flavonol ) Flavanones Flavanonols Flavans Anthocyanidins

20. Structure: Chemically, they have the general structure of a 15carbon skeleton, which consists of two phenyl rings (A and B) and heterocyclic ring (C). This carbon structure can be abbreviated C6C3C6. The chemical group in flavonoids is O-heterocyclic compounds. The three cycle or heterocycles in the flavonoid backbone are ring A, B and C. Ring A usually shows a phloroglucinol substitution pattern .

21. Chemistry: Flavonoids are the most important plant pigments for flower coloration, producing yellow or red/blue pigmentation in petals designed to attract pollinator animals . Foods with a high flavonoid content include parsley , onions , blueberries and other berries, black tea, green tea and oolong tea, bananas, all citrus fruits, Ginkgo biloba, red wine,cauliflower,etc .,.

22. Anthocyanins : Anthocyanins (also anthocyans; from Greek :(Anthos)- flower +(kyanos ) = blue). They belong to a parent class of molecules called flavonoids as ,they are odorless and nearly flavorless, contributing to taste as a moderately astringent sensation . Occurrence: Anthocyanins occur in all tissues of higher plants, mostly in flowers and fruits but also in leaves, stems, and roots . In these parts, they are found predominantly in outer cell layers such as the epidermis and peripheral mesophyll cells and also cell vacuole.

23. No fewer than 109 tons of anthocyanins are produced in nature per year . According to 2003, more than 400 anthocyanins had been reported while more recent literature (2006), puts the number at more than 550 different anthocyanins. Not all land plants contain anthocyanin; in the Caryophyllales (including cactus, beets, and amaranth), they are replaced by betalains. Anthocyanins and carotenoids contribute distinctive pigmentation to blood oranges.

24. Structure: The basic structure of anthocyanins is 2-phenylbenzopyrylium of flavylium salt. They differ in the number of polyhydroxy and/or polymethoxy derivatives of the salt. An anthocyanin pigment is composed of an aglycone esterified to 1 or more sugars with O-heterocyclic compunds (chemical group) . When the sugar moiety of an anthocyanin is hydrolyzed ,the aglycone (non-sugar hydrolysis product)is called Anthocyanidin . The anthocyanins are subdivided into the sugar-free anthocyanidin a glycones and the anthocyanin glycosides .

25. Chemistry: They are water soluble pigments that may appear red, purple, or blue depending on the pH. Roughly 2% of all hydrocarbons fixed in photosynthesis are converted into flavonoids and their derivatives such as the anthocyanins. Plants rich in anthocyanins are such as berries ,blackcurrant , cherry, eggplant peel, black rice, grapes, red cabbage,peaches and apples. Anthocyanins are less abundant in banana,asparagus , pea, fennel, pear, and potato, and may be totally absent in certain cultivars of green gooseberries

26. Tannins: Occurrence: A tannin are special compounds ,water soluble polyphenolic compounds with molecular weight between 500-3000. The tannin compounds are widely distributed in many species of plants, where they play a role in protection from predation. They are commonly found in both gymnosperms as well as angiosperms . The most abundant polyphenols are the condensed tannins and comprising up to 50% of the dry weight of leaves . Tannins are found in leaf, bud, seed, root , stem tissues and vacuoles or surface wax of plants, mostly found in the growth areas of trees.

27. Structure of tannins: There are three major classes of tannins: Hydrolyzable tannins(Gallic acid) Non-Hydrolyzable or condensed tannins(Flavone) Phlorotannins ( Phloroglucinol ) Typically, tannin molecules require at least 12 hydroxyl groups and at least five phenyl groups to function as protein binders. Chemical group is O-heterocyclic compounds . Particularly in the flavone derived tannins, the base shown must be (additionally) heavily hydroxylated and polymerized in order to give the high molecular weight polyphenol

28. Chemistry : It is an astringent, bitter plant polyphenolic compound that binds to and precipitates proteins , gelatins and alkaloids . Tannins range in color from yellowish –white to light brown. Their ability to precipitate proteins makes them available as clarifying agents. Bark of the oak tree and grape seeds are sources of tannins.

29. Betalains: Occurrence: The name "betalain" comes from the Latin name of the common beet (Beta vulgaris), from which betalains were first extracted. Betalains are a class of red and yellow indole derived. These p igments found in plants of the Caryophyllales, where they replace anthocyanin pigments . They are most often noticeable in the petals of flowers, but may color the fruits, leaves, stems, and roots of plants that contain them . Betalains water-soluble pigments found in the vacuoles of plant cells

30. There are two categories of betalains : 1.Betacyanins: It include the reddish to violet betalain pigments. Betacyanins present in plants include betanin,isobetanin , probetanin , and neobetanin . 2.Betaxanthins: They are those betalain pigments which appear yellow to orange. Betaxanthins in plants include vulgaxanthin , miraxanthin , portulaxanthin , and indicaxanthin Chemistry: Betalains absorb light strongly because their synthesis is promoted by light. They effect strongly by the environmental factors. Color is not effected by the pH.

31. Structure: It is now known that betalains are aromatic indole derivatives synthesized from tyrosine(N-heterocyclic compounds). Each betalain is a glycoside, and consists of a sugar and a colored portion For example, betalains contain nitrogen whereas anthocyanins do not . Sources of betalain are red beet root,swiss chard,cactus pear and amaranth.

32. Quinones : Occurrence: They are widely distributed in plants , specifically trees , which gives color of wood and bitter in taste. Derivatives of Quinone's are common constituents of biologically active molecules. Some serve as electron acceptors in electron transport chains such as those in photosynthesis (plastoquinone, phyllo Quinone) and aerobic respiration (ubiquinone ).

33. Chemistry : Most Quinone are bitter in taste. Their contribution to the color of the plant is minimal. Color changes occurs by the addition of hydroxyl groups. Structure: A Quinone is a class of organic compounds that are formally "derived from aromatic compounds by conversion of an even number of –CH= groups into –C(=O)– groups with any necessary rearrangement of double bonds",resulting in "a fully conjugated cyclic dione structure".

34. The class includes some heterocyclic compounds. They are oxidized derivatives of aromatic compounds and are often readily made from reactive aromatic compounds such as phenols and catechol's. These phenolic compounds varying in molecular weight from a 1,4Benzoquinone(monomer), 1,4Naphthoquinone(dimer) and 9,10Anthraquinone(trimer) to a polymer hypercin . Compounds with complex substitutes such as Naphthoquinone , Anthraquinone occur in plants and these have deep purple to black hues. 1,4Naphthoquinone 1,4Benzoquinone 9,10Anthraquinone

35. Xanthones: Occurrence: These pigments are yellow, phenolic pigment's, they are confused with Quinone's and flavones because of their structural characteristics. Many xanthones are phytochemicals,found in plants. (In the families Bonnetiaceae,Clusiaceae , Podostemaceae ). Some xanthones are found in the pericarp of the mangosteen fruit (Garcinia mangostana ).

36. Structure: Xanthone is an organic compound with the molecular formula C13H8O2. The chemical structure of xanthone forms the central core of a variety of naturally occurring organic compounds, such as mangostin , which are sometimes collectively referred to as xanthones or xanthonoids . The xanthone mangiferin occurs as a glucoside in mangoes.

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