A REVIEW ON NATURAL FOOD COLORS - Dr. D. Y. Patil ... · Reshma V. Jadhav*, Santosh S. Bhujbal Dr. D. Y. Patil Institute of Pharmaceutical Sciences and Research, Pimpri, Pune - 411

Pharmaceutical Resonance 2020 Vol. 2 - Issue 2

© Published by DYPIPSR, Pimpri, Pune - 411 018 ( MH ) INDIA 12

REVIEW ARTICLE

A REVIEW ON NATURAL FOOD COLORS

Reshma V. Jadhav*, Santosh S. Bhujbal

Dr. D. Y. Patil Institute of Pharmaceutical Sciences and Research, Pimpri, Pune - 411 018

Ramesh V. Jadhav Dr. D. Y. Patil Institute of Pharmaceutical Sciences and Research Sant Tukaram Nagar, Pimpri, Pune - 411 018 Email : [email protected] Contact : +00 00000 00000

ABSTRACT:

Consumer demand for natural colors is enhanced as awareness about various toxicities of synthetic food colors. Natural plant colorants have been in high demand by the food industry for replacing synthetic colors. Many approved synthetic food colorants like quinoline Yellow, carmoisine, tartrazine have been prohibited as they proved to be toxic. Plant is huge source of natural colors like caretonoids, chlorophyll, anthocyanins and betalains which proved to be alternatives to synthetic colorants. However, replacing synthetic colors with natural colorants offers a challenge due to the higher stability of synthetic colors towards light, oxygen, temperature, and pH, among other factors. Stabilization of natural pigments is the main challenge to overcome for their utilization as food colorants. To overcome these pitfalls the emerging techniques like hydrocolloid complexation, metal complexation, microencapsulation, intermolecular and intramolecular copigmentation have been developed to enhance stability of natural food colors.

Keywords : Anthocyanins, carotenoids, chlorophylls, batalains.

1. Introduction

Color is an important factor increasing consumer’s acceptability to food products. This is due to consumers always links food color with other qualities such as ripeness, freshness, and food safety. Thus, many food products have added food colorants to make the food products more desirable and acceptable [1]. The synthetic food colors are available in different c o l o r shades. There are many reports on the toxicity of synthetic colors. Approved synthetic colors are proved to be toxic and carcinogenic [2]. This need has come from legislative action and consumer orientation against synthetic food colors [3]. The usage of large amount of synthetic colors causes pollution, disturbs the ecological balance and causes health hazards to human. Natural colors are obtained from naturally occurring sources such as plants, animals, insects, and minerals [4]. Amongst the all natural colors, plant based pigments have wide range of medicinal

benefits [5]. Nowdays the role of natural colors as food colorant is becoming increasingly important. They contribute to the most important attributes of food both for aesthetic value and for quality evaluation but also they tend to give potential health effects, as they have been observed to possess potent antioxidant activities. The expenditure in natural food color market across the globe has reached to US $ 1 billion and is constantly increasing 10 % annually [6].

Nature gives a number of compounds adequate for food coloring, such as the water soluble anthocyanins, betalains, as well as the oil soluble carotenoids and chlorophylls. However, substituting synthetic colors with natural colorants presents a challenge because the color and stability of plant pigments are dependent on various factors like structure and concentration of the pigment, light intensity, metals, pH, temperature, enzymes, oxygen, ascorbic acid, sugars [7], flexibility during processing, long lasting effect, profitability. Synthetic colorants are more favorable from all this point of view [8].

The natural colorants are ecofriendly, harmonized with nature, obtained from renewable sources and their method of preparation involves minimum possibility of chemical reactions and they are biodisposable [9]. Because of the pitfalls of existing natural food colorants, the demand for natural



Table 1 : Plant Natural Colour

colorants is continuously increased by the food processing industries. This need can be fulfilled by research to offer a more natural and healthier way of coloring foods. Thereby, plant pigment research is looking new sources of pigments [10]. Food color manufacturers therefore striving to develop new technologies to meet customer demands [4].

2. Plant natural colors:

The natural colorants in natural plants have been the source of the traditional colorants of raw as well as the processed food.

Class Color E -number

Chlorophyll Olive green E 140

Anthocyanins Red, purple, blue,

pink, magenta E 163

Carotenoids Red, orange, yellow E 160

Betalains Red, yellow E 162

2.1 Betalains:

Betalains are water-soluble, nitrogen containing plant pigments present in most plants of the order Caryophyllales. Betalains are distributed not only in edible parts of plants but also in flowers, leaves, stem and bracts. These are classified into two groups,violet betacyanins and the yellow betaxanthins. Both groups shared betalamic acid as the structural and chromophoric unit. Betalamic acid is condensed with amines and amino acids in betaxanthins and with cyclo-DOPA in betacyanins.

Betanidin is the aglycone of most betacyanins; different substitution like glycosylation and acylation patterns of one or both hydroxyl groups located at position 5 or 6 of betanidin result in the formation of the various betacyanins. Most of these are 5-O-glucosides, and rarely are 6-O glucosides [11]. Glycosylation of the 5-O-glucoside is very common and so is esterification with hydroxycinnamic acids. The most common betacyanin is betanidin-5-O- glycoside called as betanin, the major pigment in red beet roots [12]. All betalains manifest absorption maxima in both UV and visible regions due to the phenolic nature of betalamic acid and the conjugated dienes of 1,7-diazaheptamethin substructure, respectively [13]. However, these pigments are prone to different physicochemical factors, such as light, heat, high pH (>6), air and various metals [14].

Betalains is comparatively stable over the broad pH range from 3 to 6, which allows their incorporation in low acidic foods. Below pH 3.5, the absorption maxima shifts toward lower wavelengths, and above pH 7 the shift is towards upper ones. Optimal pH range for maximum betalain stability is 5–6. Alkaline conditions results in aldimine bond hydrolysis, while acidification produces recondensation of betalamic acid with the amine group of the addition residue. The storage of betanin solutions under low oxygen levels results in reduced pigment degradation than under air atmosphere. Betalain light induced degradation is oxygen dependent, because the effects of light exposure are insignificant under anaerobic conditions. Temperature is the foremost affecting factor on betalain stability during food processing and storage. Some studies reported increasing betalain degradation rates resulting from increase in temperatures. During heat processing, betalain may be degraded by isomerisation, decarboxylation or cleavage results in a gradual decline of red color, and eventually the formation of a light brown color [15]. Hence, these pigments have potential to be used as colorants in frozen foods, low temperature dairy products and short shelf life food products [16].

Betalains can be stabilized to a definite extent by antioxidants, such as ascorbic acid , isoascorbic acid, citric acid, and other preservatives, whereas antioxidant phenolic molecules have no stabilization effect on the pigments [17]. To enhance the stability of betalains, blanching is usually done to inactivate the betacyanin decoloring enzyme, which tends to color fading [18]. Betalain stability was improved when combined with b-cyclodextrin probably due to the formation of a 1:1 inclusion complex [19].

Examples of plants containing betalains:

Betacyanins Betaxanthins

Beta vulgaris (Amaranthaceae)

Mirabilis jalapa (Nyctaginaceae)

Amaranthus caudatus (Amaranthaceae)

Portulaca grandiflora (Portulacaceae)

Gomphrena globosa (Amaranthaceae)

Opuntia ficus-indica (Cactaceae)

Bougainvillea glabra (Nyctaginaceae)

Stenocereus pruinosus (Cactaceae)

Table 2 : Plants containing Betalains

2.2 Chlorophyll:

Chlorophylls are oil soluble and the most widespread distributed pigments responsible for the



Characteristic green color of plants [20]. The structure of chlorophylls is porphyrins or tetrapyroles chelated with a centrally located magnesium atom. The main chlorophylls in foods are chlorophyll a and chlorophyll b. These chlorophylls are different at position 7, where chlorophyll a contains –CH3 and chlorophyll b contains –CHO. This difference leads to the difference in their color; chlorophyll a appears blue-green, while chlorophyll b have yellow-green color [21].

Chlorophylls are highly sensitive to heat, light, oxygen, acids and enzymes, leading to their prompt degradation and color change. They are stable in alkaline pH between 7-9. It is unstable in acidic pH. When exposed to light or heat, the cell membrane of the plant degenerate releasing acids which decrease the pH [22]. Acids and Mg-dechelatase, which is an enzyme found in algae and plants, are the main

Fig. 1 : Degradation reactions of Betalains in food

reason of changing of the chlorophylls color from green to olive brown. These changes occurs due to the loss of central magnesium atom in the chlorophylls structure, with the substitution of hydrogen ions, leading to the transformation of the chlorophylls structure from native chlorophylls to pheophytin, which manifest olive brown color [23].Other enzymes such as chlorophyllase and oxidative enzymes like lipoxygenase, chlorophyll oxidase and peroxidase are also responsible for chlorophylls degradation and cause color change [20].

Enzymes and acids are the major factors affecting the degradation of chlorophylls thus, enhancing the stability of chlorophylls pigments can be done by inactivating the enzymes or preventing an acidic condition. Blanching is a short time thermal treatment, which is usually done by exposing a



sample to hot water or steam, to inactivate enzymes involving in the change of color of plant materials [24]. Complexation of chlorophylls into metal complexes of chlorophyll derivatives e.g., copper pyropheophytin and zinc pyropheophytin has been proposed to alleviate the above problems. Chlorophylls can be transformed into metallo-chlorophyll derivatives, which display green color like native chlorophylls but having more stability to acids and heat. Although both copper and zinc ions can be used for metallochlorophyll derivatives formation, zinc ions are of greater interest due to the toxicity of copper ions [20].

Fig. 2 : Structure of chlorophyll

2.3 Carotenoids:

Carotenoids are plant pigments with 40 carbon atoms molecule. Carotenoids have provitamin A activity because the body can convert them into retinol [25]. Carotenoids are lipid soluble, yellow–orange red pigments found in all higher plants and some animals. Carotenoids can be classified into carotenes containing only carbon and hydrogen, and xanthophylls made up of carbon, hydrogen, and oxygen. It is more stable at pH between 4.0 and 6.0. Degradation of carotenoids is mainly occurs due to reactions of oxidation and isomerization, which tend to a decrease in the redness and yellowness of a plant pigments [26].

There are various factors affecting the oxidation and isomerization of carotenoids. Oxygen causes oxidation of carotenoids; the reaction can also be raised by light, heat, peroxide, metal ions and enzymes [27]. Most carotenoids in plants are trans-isomer, while isomerization of the trans-isomer to cis-isomers occurs during food processing [28]. Inactivation of oxidative enzymes is among the possible way to prevent carotenoids oxidation. Hot water or steam blanching is a simple pretreatment method that can be utilized to inactivate enzymes such as lipoxygenase, which catalyzes oxidative decomposition of carotenoids. Chemical pretreatments are another alternative method to prevent the oxidation of carotenoids. Antioxidant

agents (e.g., butylated hydroxyanisol, pyrogallol and citric acid) are proposed to prevent pigment degradation by oxidation [29].

Inspite of adding acid-based antioxidants leads to a decrease in the pH of a sample; when the pH of a sample becomes less than 3.0, carotenoids would start to decompose. The pH of a sample should be particularly controlled when acid-based antioxidants such as organic acids are used [30].

2.4 Anthocyanins:

Anthocyanins are water soluble plant pigments. They are responsible for the blue, purple, red and orange colors of many fruits and vegetables [31]. They occur mainly as glycosides of their respective aglycone anthocyanidin chromophores with the sugar moiety generally attached at the 3-position on the C-ring or the 5- position on the A-ring. Only six antocyanidin are common namely, cyanidin, delphinidin, petunidin, peonidin, pelargonidin, and malvidin which are widely spread and of great importance in human diet and health. The array of anthocyanins are due to the number and position of hydroxyl and methoxy groups on the basic anthocyanidin skeleton. If hydroxyl groups predominate, then the color goes toward a more bluish shade; if more methoxyl groups predominate, then redness is increased.

The color stability of anthocyanins is affected not only by the structural features, but also by the pH, temperature, light, presence of co-pigments, enzymes, oxygen and sugars. In a high acidic media the red flavylium cation is the only predominating equilibrium species. Increasing the pH results in decrease of both the color intensity and the concentration of the flavylium cation, as it is hydrated by nucleophilic attack of water, to the colorless carbinol form. The carbinol form has lost its conjugated double bond between the A and B ring and therefore does not absorb visible light . Also a rapid proton loss of the flavylium cation takes place as the pH shifts higher and the colored quinonoidal form rises. When pH increases further, the carbinol form yields, through ring opening, the colorless chalcone [32].

Heat is another an important factor affecting the color and stability of natural pigments. However, anthocyanins are more stable to heat than the pigments. Degradation of anthocyanins occurs when temperature approaches 100 °C or even higher [33]. The first step of thermal degradation involves the formation of colorless carbinol pseudobase and subsequent opening of the pyrylium ring to form chalcone, before converting into a brown degradation product [34].



Fig. 3 : Degradation reactions of chlorophyll in foods

Fig. 4 : Structure of common carotenoids

Fig. 5 : Degradation reaction of carotenoids in foods

Caretonoids Food sources

α-carotene Buriti (Mauritia vinifeva), carrot, Cucurbita moschata, red palm oil

β-carotene

Carrot, acerola (Malpighia glabra), apricot, bocaiava (Acronomia makayliyba), broccoli, buriti, cantaloupe, carrot, Cucurbita maxima, Cucurbita moschata, green leafy vegetables, mamey (Mammea Americana), mango, peach palm (Bactris gasipaes),

pink grapefruit, red palm oil, red pepper, yellow and orangefleshed

sweet potato, tucum5 (Astrocayum vulgare)

β -cryptoxanthin

Caja (Spondias lutea), pitanga (Eugenia uniflora), red pepper,

tree tomato (Cyphomandra betacea)

lycopene

Pink grapefruit, pink-fleshed guava, red-fleshed papaya, pitanga

(Eugenia uniJora), tomato, watermelon , tomato

Lutein

Green leafy vegetables, broccoli, Brussels sprout, corn, Cucurbita

maxima

zeaxanthin Buriti, corn

Table 3 : Plant sources of carotenoids

In addition to a proper pH adjustment, the source of anthocyanins must be considered to obtain the most stable colorant. Different sources of plant materials contain different anthocyanins structure, which affect their stability. Anthocyanins from red cabbage, black carrot, red radish and red sweet potato are reported to be more stable to heat and pH change than anthocyanins from other sources due to their acylation. Acylation of the anthocyanin molecules can enhance the stability through intramolecular copigmentation. Higher stability of acylated anthocyanins is due to the stacking of acyl group with the pyrylium ring of the flavalium cation, thus retarding the nucleophile attack of water and subsequent formation of chalcone. Many researchers have indeed reported the stability of acylated anthocyanins as compared with that of nonacylated anthocyanins [35].



Anthocyanin Color

Pelargonidin Orange

Cyanidin Red

Delphinidin Blue

Peonidin Reddish purple

Malvidin Voilet

Petunidin Purple

Table 4 : Common anthocyanins and their associated colors

Plants containing Anthocyanins:

Plant Anthocyanidins

Apple, red cabbage, peach, rasberry Cyanidin

Black current Cyanidin , delphinidin

Cherry,plum Cyanidin, peonidin

Red radish Pelargonidin

Blueberry Cyanidin,delphinidin, peonidin, malvidin

Strawberry Pelargonidin, cyanidin

Grape Malvidin, peonidin, delphinidin, cyanidin, pelargonidin

Table 5 : Common sources of anthocyanins

Fig. 6 : Structure of common anthocyanins

Fig. 7 : pH behavior of Anthocyanins



Fig. 8 : Degradation reaction of anthocyanin in foods

Conclusion

Color is the main feature of any food item as it enhances the appeal and acceptability of food. Although worldwide possesses large plant resources, only little has exploited so far. Natural colors are highly unstable with various food processing conditions. Stabilization of natural pigments is the main challenge to overcome for their utilization as food colorants. Thus, more detailed studies and scientific investigations are needed to assess the real potential and availability of natural dye-yielding resources. The food industry that develops and manufactures natural food colors is growing exponentially as a result of consumer demands for natural pigments in lieu of synthetic colorants.

References:

[1] Duangmal, K., Saicheua, B., Sueeprasan, S. Ro selle anthocyanins as a natural food colorant and improvement of its color stability. AIC Color and Paints, Interim Meeting of the Inter national Color Association. 2004; 155-158.

[2] Ozkan, G., Bilek, SE. Microencapsulation of natural food colorants. International Journal of

Nutrition and Food Science. 2014; 3(3): 145- 156.

[3] Var, A., Cevallos-Casals., Zevallos LC. Stabil ity of anthocyanin-based aqueous extracts of Andean purple corn and red-fleshed sweet pota to compared to synthetic and natural colorants. Food Chemistry. 2004; 86: 69–77.

[4] Meena Devi, VN., Ariharan VN., Nagendra PP. Annato: Ecofriendly and potential source for natural dye. International Research Journal of Pharmacy. 2013; 4(6):106-108.

[5] Scotter MJ. Emerging and persistent issues with arti¢cial food colours: natural colour addi tives as alternatives to synthetic colours in food and drink. J. Quality Assurance and Safety of Crops & Foods. 2011; 3:28-39.

[6] Tsai, PJ., McIntosh, J., Pearce, P., Camden, B., Jordan TB. Anthocyanin and antioxidant capac ity in roselle (Hibiscus Sabdariffa L.) extract. Food Research International. 2002; 35: 351- 356.

[7] Reshmi, SK., Arvindhan, KM. The effect of Light, Temperature, p H on stability of on the



stability of Betacyanin pigments in Basella Al ba fruits. Asian Journal of Pharmaceutical and Clinical Research. 2012; 5(4): 107-110.

[8] Eva Nemeth. Colouring plants. Encyclopedia of Life Support Systems, 1-6.

[9] Joshi, P., Jain, S., Sharma V. Acceptability as sessment of yellow color obtained from turmer ic in food products and at consumer level. J. Food Ag-Ind. 2011; 4(1) : 1-15.

[10] Agrawal A. Scope of Betalains as a food color ants. International journal of advanced scien tific and technical research. 2013; 3(3): 22-36.

[11] Delgado-Vargas, F., Jimenez, AR., Paredes- Lopez, O. Natural pigments: carotenoids, an thocyanins, and betalains - characteristics, bio synthesis, processing, and stability. Critical Re views in Food Science and Nutrition. 2002; 40: 173–289.

[12] Stintzing, FC., Carle, R. Functional properties of anthocyanins and betalains in plants, food, and in human nutrition. Trends in Food Science and Technology. 2004; 15: 19–38.

[13] Gand-Herrero, F., Jim enez-Atienzar, M., Cabanes, J., Garc-Carmona, F., Escribano J. Stabilization of the bioactive pigment of Opun tia fruits through maltodextrin encapsulation. J. Agric. Food. Chem. 2010; 58:10646–10652.

[14] Herbach, KM., Stintzing, FC., Carle R. Betalain stability and degradation—structural and chro matic aspects. Journal of Food Science. 2006; 71:41–50.

[15] Henriette, MC., Azeredo. Betalains: properties, sources, applications, and stability – a review. International Journal of Food Science and Technology. 2009; 44: 2365–2376.

[16] Altamirano, RC., Drdak, M. Simon, P., Rajnia kova, A., Karovicova, J., Preclík L. Thermal degradation of betanine in various water alco hol model systems, Food Chem. 1993; 46: 73– 75.

[17] Khan MI. Stabilization of betalains: A review. Food Chemistry .2016; 197: 1280–1285.

[18] Delgado-Vargas, F., Paredes- Lopez, O. Natu ral Colorants for Food and Nutraceutical Uses. 2003; CRC Press, Boca Raton.

[19] Drunkler, DA., Fett, R., Bordignon Luiz, MT. The evaluation of stability of betalains in beet root (Beta vulgaris L.) extract addition of α, β

and γ-cyclodextrins. B.CEPPA. 2006; 24 (1):259–276.

[20] Levent İnanc, A. Chlorophyll: Structural Prop erties, Health Benefits and Its Occurrence in Virgin Olive Oils. Academic Food Journal. 2011; 9(2): 26-32.

[21] Steet, JA., Tong, CH. Degradation kinetics of green color and chlorophylls in peas by color imetry and HPLC. J Food Sci. 1996; 61: 924- 928.

[22] Ozkan, G., Bilek, SE. Enzyme-assisted extrac tion of stabilized chlorophyll from spinach. Food Chem. 2015; 176: 152–157.

[23] Attoe, EL., Von Elbe, J H. Photochemical deg radation of betanine and selected anthocyanins. J. Food Sci. 1981; 46: 1934–1937.

[24] Bahceci, KS., Serpen, A., Gokmen ., Acar, J. Study of lipoxygenase and peroxidase as indi cator enzymes in green beans: Change of en zyme activity, ascorbic acid and chlorophylls during frozen storage. J Food Eng. 2005; 66: 187–192.

[25] Khachik, F. Distribution and metabolism of di etary carotenoids in humans as a criterion for development of nutritional supplements. 14th International Symposium on Carotenoids. 2006; 78:1551-1557.

[26] Provesi, JG., Amante, ER. Changes in carote noids during processing and storage of pump kin puree. Food Chemistry. 2011; 128: 195– 202.

[27] Boon, CS., McClements, DJ., Weiss, J., Deck er, EA. Factors influencing the chemical stabil ity of carotenoids in foods. Crit Rev Food Sci Nutr. 2010; 50: 515–532.

[28] Khoo, HE., Prasad, KN., Kong, KW., Jiang, Y., Ismail A. Carotenoids and their isomers: Color pigments in fruits and vegetables. Molecules. 2011; 16: 1710–1738.

[29] Otles S, Agindi. Carotenoids as natural color ants. In Socaciu C, eds. Food Colorants: Chem ical and Functional Properties, 1st ed., New York : Boca Raton publishers.; 2008: 51–70.

[30] Qian, C. Decker, EA., Xiao, H., McClement, DJ. Physical and chemical stability of β- caro tene-enriched nanoemulsions: Influence of pH, ionic strength, temperature, and emulsifier type. Food Chem. 2012; 132: 1221–1229.



[31] Mazza GJ. Anthocyanins and heart health. Ann. Ist. Super. Sanita. 2007; 43: 369-374.

[32] Miguel MG. Anthocyanins: Antioxidant and/or anti-inflammatory Activities. Journal of Ap plied Pharmaceutical Science. 2011; 1 (6); 7- 15.

[33] Jackman, RL., Smith, JL. Anthocyanins and betalains. In Hendry, GA F, Houghton J D, eds. Natural Food Colorants, 2nd ed., New York: Chapman & Hall publishing Co.; 1996:244– 309.

[34] Perera OC, Baldwin EA. Biochemistry of fruits and its implications on processing. In Arthey D, Ashurst PR, eds. Fruit Processing: Nutrition, Products and Quality Management, 2nd ed., Gaithersburg : Aspen Publishers.; 2004:25–27.

[35] Bąkowska, A., Kucharska, AZ., Oszmianski J. The effects of heating, UV irradiation, and stor age on stability of the anthocyanin–polyphenol copigment complex. Food Chem. 2003; 81: 349–355.

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A REVIEW ON NATURAL FOOD COLORS - Dr. D. Y. Patil ... · Reshma V. Jadhav*, Santosh S. Bhujbal Dr. D. Y. Patil Institute of Pharmaceutical Sciences and Research, Pimpri, Pune - 411