Introduction: The production and recovery of synthetic
Introduction: Substanceswith intense colors are often called colorants. Colorants may be natural or synthetic. Colorants are any substances that are added to food orcosmetics to change or enhance its color. Colorants used for textile and foodsare often called dyes. Colorants used for inks, paints and cosmetics are oftencalled pigments. Theuse of natural dyes began back in 2600BC in China and adding colorants to foodsand things used for appearance, but known today as cosmetics was in Europeduring the Bronze age.
In 1856, Sir William Henry Perkin created the firstsynthetic color. The production and recovery of synthetic colors came from the petroleum-derivedproducts like aniline. They were called “coal tar colors because the startingsubstance were taken from coal (Lakshmi, 2014).
Sourcesof natural colorants are plants, but also can be animals and minerals. They are extracted from natural things likefruits, vegetables, insects, leaves, algae, seeds and etc. In order for the useof these colors, they must be certified through the Food & DrugAdministration (FDA). The FDA uses the U.S. Federal Food, Drug, and CosmeticAct(FD & C Act) to oversee the safety of food, drugs, and cosmetics.Congress passed this set of laws in 1938. A dye that is labeled “FD &C” meansit can only be used in foods, drugs, and cosmetics.
Labeled “D & C” meansit can only be used for drugs and cosmetics (Calvo, 2001). Thereare 26 colors that are permitted to be used in food and 28 to be used incosmetics and pharmaceuticals (drugs). Natural colorants are mainly used onfood and synthetic colorants are mainly used on cosmetics. A few commonly used natural colors are Annatto(seed), turmeric, beet juice (root), red Cabbage (vegetable), spinach (leaf),anthocyanin, carotenoids, chlorophyll, and caramel.
Easy availability of these fooddyes is also one of the reasons for their popularity. But the driving reasonbehind the popularity of natural food colors is the concern that revolvesaround the synthetic food colors like tartrazine. Syntheticcolors have their drawbacks because of the chemicals used to create theproduct. So the demand for natural colors in the international marketincreased. For example Japan and European countries have banned tradingsynthetic color made products. They encourage the use of natural colors incrayons, organic textile printing, infant toys, etc., but natural colorsobtained from plants, animals, and minerals also known as bicolor had theirdrawbacks. For instance, heat, pH and light stability, and oxidizing agents infood (Lakshmi, 2014).
This is what led to synthetic colors gaining awareness incosmetics and food industries. In contrast,synthetic colors are easier to produce, inexpensive and far much better incoloring properties when needed to blend. Even though synthetic colors gainedpopularity so did the safety concerns across the world and in the United Statesof America (USA). That led to only seven synthetic colors to be authorized.
Naturalcolorants are in demand today than synthetic colors. They are safer with infood. Since they are obtained naturally they are free of harmful side effects.They are only harmful to those who have certain allergies and intolerances.
Things like that are only individual problems and are not generalized. But the driving reason behind the growingdemand of natural food colors is the concern that revolves around the syntheticfood colors like tartrazine Dyes are certified, water soluble syntheticfood colorants. They are manufactured as powders, granules and liquids. Thesynthetic dyes are of several types as per their basic compound and structure. Chemistry of Natural Colorants Turmeric: Turmeric is a root that has beenused to add color to food and cosmetics for centuries. Grinding the rhizomes ofthe perennial herb, Curcuma longa, which is native to India, South America,China, and the East Indies, produces it.
It alsohas another name known as Indian Saffron. It has been used in Indian cookingfor centuries Curcumalonga is one of the most essential spice used all over the world. It is calledthe ” golden spice of life” (Lakshmi, 2014). The primary color is curcumin,which is an orange- yellowish color. Curcumin is oil soluble and seems to fadein light but has good heating stability.
Many food industries uses it forcoloring. It is predominantly used in dairy products, beverages, cereal,pickles, sausages, soups, ice cream, and bakery. It is also used for skin careand hair care cosmetics products such as foundation, shampoos, face cream, facesoup and eye shadow because it is antibacterial in nature. It has typical turmeric like odor, which is very strong. Curcuminare naturally insoluble in water but manufacturers have found a way to use itin beverages by using particle size reduction and emulsifiers. This allows itto be used in aqueous and lipid solutions or products Figure 2: Structure of curcumin pigment.
Carotenoids:Carotenoids are yellow, red or orange pigments that arespread in both plant and animal world. They occur in annatto, carrots,oranges, prawns, red peppers, saffron, tomatoes, and palm fruits. Carotenoids can occur in naturein four states; crystals, esters of fatty acids, combinations with sugar, andothers with protein (Butnariu,2016).Carotenoids wereidentified in a free form in natural products. Carotenoids are divided into: carotenoidhydrocarbons and oxygenated derivatives of hydrocarbon carotenoids.
Hydrocarboncarotenoids are carotenoids with 40 carbon atoms, formula C40H56. In figure 3 themost important of these are shown: lycopene (red carotenoid pigment),?–carotene (alpha-carotene is a precursor to retinoic acid, or a provitamin Acompound), ?–carotene (Butnariu, 2016). Figure 3: This figure demonstrates the structures of the mostimportant carotenoids (ButnariuM, 2016).
Lycopeneare acyclic carotenoid formed from the sequential desaturation. It is acrystalline material. It has a red–purple color. It is insoluble in water and solublein organic solvents.
The color of fruits and tomatoes are obtained fromlycopene. ?–carotenehas a form of carotene with a ?-ionone ring at one end and a ?-ionone ring atthe opposite end. It is a copper–colored crystalline substance soluble inorganic solvents. Alpha-carotenes are antioxidant. Theygive the color orange and red fruits and vegetables. ?–caroteneis composed of two retinyl groups. By heating ?–carotene it can be converted into?–carotene. It is found in plants insmaller quantities than ?–carotene.
?–carotene has a red orange colored fats solubleterpenoid with antioxidant properties It is soluble in organic solvents.Figure 4: This chart is representations of the kinds of plants themost important carotenoids are found in. The data was taken from the databasefor flavonoid content of selected foods. Table 1: CarotenoidsStructures Structures Examples of Carotenoids Hydrocarbons Hexahydrolycopene, Lycopersene, Phytofluene, Torulene, and ?–zeacarotene Acids and Acid Esters Torularhodin, and Torularhodin methyl ester Esters of Alcohols Astacein, Fucoxanthin, Isofucoxanthin, Physalien, Siphonein, and Zeaxanthin Glycosides Oscillaxanthin, and Phleixanthophyll Nor– and Seco–carotenoids ?–carotenone, Actinioerythrin, Peridinin, Triphasiaxanthin, and Pyrrhoxanthinino Thereare many representatives of these derivatives such as: xanthophylls,carotenoids ketones, and carotenoid acids.
Xanthophylls are hydroxylderivatives of carotenoid hydrocarbons, which comprise a diverse group ofoxygenated carotenoids with varied structures and complexes functions. Responsiblefor yellow colorants less hydrophobic Figure 5: Chemical structure of Xanthophylls Carmine/Cochineal: Cochineal is a native insect of South America and Mexico.It is a parasite that lives on cacti of genus Opuntia. It feeds on the moistureand nutrients of the cactus. These female insects are used to produce a deepred color. The dye extracted from the insects comes from their eggs.
It iscalled carminic acid (C22H20O13) alsoknown as Carmine. For centuries, the Aztecs used these insects to dyefabrics a deep-red color. If you crushup 70,000 of these bugs, you can extract a pound of a deep-red dye (Lakshmi,2014). This dye is safe to ingest, so it found its way into a variety offood and cosmetic products that required a red color. It is found in food suchas juices, ice cream, yogurt, and candy and in cosmetic products such as eyeshadow and lipstick.Carminic acid’s main color thatis produced is red but it also can be pink purple, or even orange coloringdepending on the extraction method being used, such as using water oralcohol.
When the carminic acid isextracted in low pH it is orange but in high pH it is purple. The color changeis due to phenolic groups on the carminic acid molecule being affect by he pHlevels of solvents (“Carmine/Cochineal | DDW The Colour House”, 2017). Figure 7: Chemical Structure of Carminic Acid Chlorophyll: Chlorophyll is a green pigment foundin most plants, algae, and cyanobacteria. The name was derived from the Greekwords “chloros” meaning green and “phyllon” meaning leaf(Lakshmi, 2014).Chlorophyll is the most widely distributed natural plant pigment, present inall green leafy vegetable. Chlorophyll is a green, oil soluble color.Chlorophyllins are water-soluble and when exposed to heat and light it issomewhat stable. Uses include sugar confectionery, dairy products such as icecream, and dry beverage mixes.
They naturally occur in alfalfa grass, nettles,parsley, and spinach (“Chlorophyll/ Chlorophyllins | DDW The ColourHouse”, 2017). Structure of Chlorophyll: Chlorophyll is a green pigment that is similar to other porphyrinpigments, such as heme. In Figure 5 at the center of the chlorophyll structurethere is a magnesium ion. The chlorinring is connected to different side chains. The most widely distributed form ischlorophyll a. Hans Fischer interpreted the structure of chlorophyll in 1940 (Lakshmi,2014). The pigments chlorophyll a produces are blue-green and chlorophyll bproduces yellow-green pigments.
As shown in Figure 9 the figure differ at oneof the carbons on the top. Chlorophyll a has a methyl (-CH3) while chlorophyllb has an aldehyde( -OCH). This contributes to their varying in light absorptionphysical properties. Chlorophylla absorbs blue, red and violet wavelengths in the visible spectrum. Itparticipates mainly in oxygenic photosynthesis in which oxygen is the mainby-product of the process. Chlorophyll b primarily absorbs blue light and isused to complement the absorption spectrum of chlorophyll a by extending therange of light wavelengths a photosynthetic organism is able to absorb (Perdue,2017). Chlorophyll a Chlorophyll bFigure 8:Showschlorophyll in the form of a and b. The difference between them is thatchlorophyll a has a –CH3 at the top of the structure, while chlorophyll b has a–OCH.
(Lakshmi, 2014) Anthocyanin:Anthocyanin is the pigment compoundresponsible for red, purple and blue colors in many fruits and vegetables (Lakshmi, 2014).Within each plant source, these pigment compounds vary in concentration,proportions, and chemical structure, all of which influence use for color in afood or beverage. The pH causes a shift from red to purple to blue, from low tohigh pH respectively, while heat and light degrade the pigments. The effects ofthe pH change the structure of the anthocyanin present. Anthocyanin is synthesized withinthe plants from flavanol-derived structures called anthocyanidins (“Anthocyanin| DDW The Colour House”, 2017).
Examples of anthocyanidins include: delphinine,pelargonidin, and cyaniding. Delphinine varies from blue to purple whilecyanidin is from red to purple. Pelargonidin is from orange to red color (Blackburn& Trejo, 2016). These anthocyanidins are thebuilding blocks that are further reduced, dehydroxylated and glycosylatedwithin the plant to produce anthocyanins. Anthocyanins further vary insubstitution patterns and glycosyl groups, both of which affect their color andstability. Additionally, these pigments exhibit a reversible change inmolecular structure as the pH of solutions change from acidic to basic. Thischange in structure is characterized by a shift in hue from red to purple toblue as the pH changes from acidic to basic. At low pH (around 3), the anthocyanins are moststrongly colored, exhibiting their well-known purple–red color.
Around pH 5,anthocyanins turn almost colorless, and at neutral and alkaline pH the colorgoes from blue to green (Mortensen, 2006). Anthocyanins can be blended togetherto enhance the visual appearance of the food or beverage product. Figure 9: This is a representation of anthocyanidinwith a R1 and R2 group.
The R1 and R2 group can be replaced by –OH, -H, and-OCH3. Combinations of these groups represent certain anthocyanidin colors (Lakshmi, 2014). Table2: Anthocyanidin Colors Anthocyanidin Color R1 R2 Cyanidin Red-purple OH H Delphinidin Blue-purple OH OH Pelargonidin Orange-red H H Malydin Deep purple OCH3 OCH3 Peonidin Red OCH3 H Petunidin Purple OH OCH3 Synthetic Colors: Synthetic colors are manufacturedchemically and are the most commonly used dyes in the food, pharmaceutical andcosmetic industries. They are also known as Artificial Colors. Seven dyes were initially approved under the Pure Food and Drug Act of 1906, but several have been delisted and replacements havebeen found. There are two types of synthetic colors, primary and blendedcolors. Primary colors are that when mixed they produce other colors. Forexample, Tartrazine, which is shown in figure 11.
It is a synthetic lemon yellow azo dye and iswater soluble, maximum absorbance at 427 nm. Blended colors areprepared from mixing of previously certified batches of primary colors. Blendedfood colors are the mixture of two or more water-soluble food coloring agentsthat are combined in numerous ways to produce a vast array of shades. Many synthetic food colors cause cancer, asthma, andhyperactivity (but specifically in children). Tartrazine is known to causeasthma and allergic reactions because of its nitrous derivatives. In the UnitedKingdom Food Standards Agency, they found in the 2007 landmark Southampton,that the fooddyes have a negative affect on children. A dye used in snack food is calledallura red, can cause lymphomas and tumors in children.
Brilliant blue dye isused in jellies, dairy products, syrups, and candy. It is derived frompetroleum distillates. It has caused death of some elderly patients because ofenteral feeding, which is done through a tube (Blackburn & Trejo, 2016). Figure 11: Showsthe seven FDA authorized synthetic colors’ structures: a) Tartrazine, b) AlluraRed c) Brilliant blue d) Sunset Yellow FCF e)Fast Green FCF f) Erythrosine g)Indigotine. Methods of Extraction ofPigments: Solventextraction is the widely used method that is usually followed to extract colorsfrom natural products such as plants. Anthocyanin and curcumin pigments are water-solubleso they are extracted from the raw material with water and sometimes withaqueous methanol (Lakshmi, 2014).
Carotenoids extraction use hexane as thesolvent of choice but acetone is better for initial extraction of pigment froma plant (Butnariu, 2016). Carminicacid extraction uses acidic, aqueous, alcoholic solution. It is thenprecipitated as carmine (“Carmine/ Cochineal | DDW TheColour House”, 2017).
After extraction of the plant material thesubstance is concentrated and put through purification steps using columnchromatography. Spectrophotometry or high-pressure liquid chromatography (HPLC)is use for identification and quantification of the pigments. Advancements inextraction have been helpful in the industry because the uses of organicsolvents are harmful for health and the environment. The advancements in colorextraction are: -High Hydrostatic Pressure (HHP)-Pulsed Electric Field (PEF)-Sonication-assisted Extraction-Gamma Irradiation-Enzymatic Extraction-Membrane Technology High Hydrostatic Pressure (HHP) andPulsed Electric Field (PEF)are environment friendly. They enhance mass transfer processes within plant oranimal cellular tissues, since the content of cytoplasmic membranes can beincreased which results the enhancement extraction of good cell components. PEFis reported to be an ideal method to enhance juice production and increase theextraction of components better than the enzymatic maceration yields (Lakshmi, 2014).
Sonication-assisted Extraction is the most used methods to enhance masstransfer phenomena by cavitation forces, so bubbles in the liquid or solidphase can collapse and generate pressure (Lakshmi,2014). This improves the release of intracellularsubstances into the solvent being used. This is well used for the extraction ofmetabolites such as tea, ginseng, and chamile. Gamma irradiation increases cell wall permeabilization, whichresults in the enhancement of cell constituents in higher yield. Enzyme extraction is another new technology for extractionof pigments antioxidants, and flavors from plant material. Enzymes cannot be acomplete replacement for solvent extraction but can result in yield beingincreased of cell components and reduced time of extraction. Enzymes are seento enhance the extraction of carotenoids in marigold flowers.
(Lakshmi, 2014) Conclusion: Coloringis very important. The choice of coloring can be very challenging. If the wrongcolor were chosen for food or cosmetic product it would lead to many problems. Themain factors to evaluate food quality are color, flavor, and texture, but colorcan be considered the most important of them, because if it is not appealingconsumers will not enjoy the flavor and texture of any given food so demandwill decrease. Coloring for cosmetics industry is vital, when making make-up,lipstick, skin and hair care products, hair dyes, and nail colorants because ifthe wrong color is chosen for cosmetic product it would lead to lack ofconsumer appeal and the failure of product. To conclude, there is a high demandin natural pigments in the food and cosmetics industry because of theirnontoxic properties and less side effects. Even though, synthetic colors areinexpensive there all many health affects, which why awareness among peopletowards natural color have increased (Chengaiah, Mallikarjuna Rao, MaheshKumar & Alagusundaram, 2010) References Blackburn, R., & Trejo,N.
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