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Natural food pigments and colorants
Accepted Manuscript Title: Natural food pigments and colorants Author: Delia B. Rodriguez-Amaya PII: DOI: Reference:
S2214-7993(15)00104-6 http://dx.doi.org/doi:10.1016/j.cofs.2015.08.004 COFS 85
To appear in: Received date: Accepted date:
11-8-2015 13-8-2015
Please cite this article as: Rodriguez-Amaya, D.B.,Natural food pigments and colorants, COFS (2015), http://dx.doi.org/10.1016/j.cofs.2015.08.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Highlights
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Natural food pigments are actively studied because of potential health benefits. A diversity of plant and microbial sources has been reported. Processing effects have been widely investigated. Commercial production of natural colorants are still limited by instability Microencapsulation and nanoencapsulation are advocated to enhance stability
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DECLARATION 1 Page 1 of 30
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I, Delia B. Rodriguez-Amaya, sole author of the manuscript “Status of carotenoid analytical methods and in vitro assays for the assessment of food quality and health effects,” certify that this manuscript is the author’s original work, has not received prior publication and is not under consideration for publication elsewhere.
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Delia B. Rodriguez-Amaya
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June 1, 2014
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Natural food pigments and colorants
Delia B. Rodriguez-Amaya
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University of Campinas, Campinas, SP, BRAZIL
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E-mail: [email protected]
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Abstract
The natural color of foods is due primarily to carotenoids, anthocyanins, betanin and
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chlorophylls, either as inherent food constituents or as food or feed additives. These compounds have drawn considerable attention in recent years, not because of their
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coloring properties, but due to their potential health-promoting effects. Their occurrence
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and levels in foods, along with the factors that influence the composition, have been widely investigated. Processing effects have been actively studied. In spite of the
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intense search for plant and microbial sources and efforts to increase yield, few natural food color additives have reached the market. Lack of stability is a major deterrent; microencapsulation and nanoencapsulation are being advocated to minimize this problem.
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Introduction
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Foods, particularly fruits and vegetables, are naturally colored mainly by four groups of
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pigments: the green chlorophylls, the yellow-orange-red carotenoids, the red-bluepurple anthocyanins and the red betanin. These pigments are also incorporated into food
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products by direct addition or indirectly through animals’ feed. Although recent studies
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have been stimulated and dominated by their importance in human health, earlier
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investigations were motivated by the color they impart.
Employing natural colors is the current marketing trend because of consumers’ concern about the safety of artificial food dyes, reinforced by possible health benefits of the natural pigments. Replacement of the former by the latter, however, is challenging because natural colorants are usually less stable, more costly, are not as easily utilized as artificial colors, require more material to achieve equivalent color strength and has limited range of hues.
Motivated by potential health effects [1-6], literature on natural pigments, especially of carotenoids, is voluminous. Focusing on the last two years, research in Food Science in
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this area generally falls under the following topics: (a) composition and influencing factors (b) search for rich plant and microbial sources or increasing the pigment content, (c) assessing and improving stability and bioavailability, (d) processing effects and (e)
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health effects.
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Carotenoids
Determination of the carotenoid composition of foods continues to be actively pursued
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worldwide, attention being currently directed to indigenous and lesser known crops [e.g. 7-9]. Several countries have their own carotenoid databases, especially of the principal
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carotenoids in foods: β-carotene, α-carotene, β-cryptoxanthin, lycopene, lutein and
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zeaxanthin. Moreover, the different factors affecting the composition have been extensively investigated [e.g. 8, 9, 10-15], documenting the influence of
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cultivar/variety, stage of maturity, climate and season, farming practice and conditions,
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processing and storage. Since the physicochemical properties (e.g. color, solubility, stability), bioavailability and efficacy as health-promoting compounds differ among
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carotenoids, quantitative data have been obtained in terms of the concentrations of individual carotenoids, now often extended to separate quantification of E- and Z- (trans and cis) isomers.
In vitro assay of bioaccessibility has also been widely conducted with results mostly coherent with those of human studies on bioavailability, demonstrating the influence of dietary factors such as nature of the food matrix, carotenoid species and their geometric configuration, carotenoid-carotenoid interaction, amount and type of fat, amount and type of dietary fiber, other food constituents, food processing [e.g. 16, 17].
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Losses of carotenoids during the processing and storage of foods have been reported in numerous papers. However, knowledge of the reactions and the underlying mechanisms is still limited. There were attempts to elucidate degradation mechanisms in the 1980s,
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but such efforts had practically ceased when attention had been directed primarily to the health benefits of these pigments. Recent years have seen renewed interest on
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degradation, stimulated by the finding that the products can have negative or positive effects on human health. The major alterations undergone by the highly unsaturated
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carotenoids during processing and storage of foods are geometric isomerization and
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oxidation (Figure 1) [18].
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To date most of commercial carotenoids, used as food and feed additives and supplements, are products of chemical synthesis (e.g. β-carotene, astaxanthin,
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canthaxanthin and zeaxanthin), although they continue to be produced from a small
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microbial fermentation.
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number of rich natural sources (annatto, paprika, saffron, marigold, tomato) and by
Rich plant sources of carotenoids, such as the Asian gac (Momordica cochinchinensis Spreng.) fruit, are actively sought. Commercial products like gac powder and gac oil have been manufactured as natural colorants and medicinal supplements [19]. The extraction of natural pigment from Canna indica flowers using ultrasound resulted in significant improvement in extraction efficiency [20]. In line with current efforts to utilize industrial wastes, extraction of lycopene from the pulp fractions of tomato processing waste was optimized, resulting in 95% maximal recovery of high purity (98%) all-E-lycopene [21].
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In spite of the intense research on microbial carotenoid production, only three have reached commercial scale: β-carotene by the alga Dunaliella sp, astaxanthin by the alga Haematococcus pluvialis, and β-carotene by the fungus Blakeslea trispora. Research on
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optimization of conditions to increase carotenoid production by Haematoccus [e.g. 22,
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23] and investigation of other carotenoid producing microorganisms [e.g. 24] continue.
Advances in knowledge of the biosynthetic pathways, cloning of the genes that code the
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enzymes and availability of gene transfer techniques have led to genetic engineering in crop plants and in microorganisms to achieve higher content or better composition of
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carotenoids [e.g. 25]. Advantages of genetic engineering over conventional breeding
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include the ability to transfer genes in a faster and targeted manner. In addition to the transfer of genes from the same species, modern recombinant technologies permit the
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introduction of genetic material from diverse plants and unrelated species such as
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microorganisms. However, a lot more investigation and new tools/resources are deemed
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necessary to better reflect the dynamic nature of biosynthetic pathways [26*].
To address the stability problem, microencapsulation and nanoencapsulation have been investigated. Optimization of microencapsulation of gac oil by spray-drying resulted in a powder having high contents of lycopene and β-carotene and attractive red-yellow color [27]. Using four modified n-octenyl succinic anhydride (OSA)-starches, the best results were achieved with OSA starch refined from waxy maize [28]. Encapsulating crocin into chitosan-sodium alginate nanoparticles, prepared by a modified ionic gelation method, provided enhanced stability under unfavorable environmental conditions [29].
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Anthocyanins For anthocyanins, quantitative analysis has been widely done in terms of the total anthocyanin content. In recent years, however, an increasing number of papers report
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individual anthocyanin concentrations, and influencing factors have also been
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investigated [12, 30-34**].
It has been reported that the phenolic bioactive forms in vivo are not necessarily those
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which occur in foods, but rather conjugates or metabolites arising from them in the human body [35*]. Anthocyanins such as cyanidin-3-glucoside and pelargonidin-3-
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glucoside could be absorbed in their intact form into the gastrointestinal wall, undergo
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extensive first-pass metabolism and enter the systemic circulation as metabolites [36].
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The color of anthocyanins depends on the pH (Figure 2). Their stability is influenced by
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such factors as their structure and concentration, pH, temperature, light, oxygen,
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solvents, presence of enzymes, other flavonoids, proteins and metallic ions.
Utilization of anthocyanins as food colorants and functional ingredients has been limited because of their low stability and interaction with other compounds in the food matrix. The FDA list of color additives has only grape color extract and grape skin extract [37]. Thus, research has been directed towards the search for better sources and enhancement of extraction efficiency and stability, as exemplified by the following publications.
Among recognized good sources of anthocyanins are many berry-type fruits, red cabbage and purple sweet potato. Cultivar and maturation affected color and stability of
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red cabbage extracts at different pH [38]. Some varieties accumulated ≥30% of diacylated pigments, and monoacylated pigments decreased with time. Acylation is known to increase the anthocyanin’s stability. Purple-fleshed sweet potatoes P40 had
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high content of anthocyanins, of which cyanidin 3-p-hydroxybenzoylsophoroside-5-
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glucoside exhibited the best thermal stability [34].
Pulsed electric fields and ultrasonication were used as environmental friendly
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alternatives to water extraction at 70oC [39]. Both technologies were able to increase the extraction of anthocyanins in plum peels. In grape peels, ultrasonication was more
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effective. Pulse electric fields increased the extraction of anthocyanins from grape peels
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several fold. Ultrasound-assisted extraction was found to be a suitable technique for the extraction of anthocyanins from haskap berries [40]. The colorant powder obtained from
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black glutinous rice bran by ohmic heating-assisted extraction had higher colorant yield,
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anthocyanin pigments and bioactive compounds than conventional methods [41].
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A liquid concentrated colorant obtained from Thymus moroderi using water/citric acid as solvent was compared with two commercial anthocyanin-rich food colorants from red grape skin and red carrot (color strength of 1.7 and 3.6 AU, respectively) [42]. T. moroderi colourant had 1.2 AU color strength and high storage stability (>97% remaining color after 110 days at 4 °C). The colorant gave a stable pink color to yogurt during one month storage under refrigeration.
The stability in micellar solutions of extracts from roselle calyx (Hibiscus sabdariffa Linn.) and lac resin (Laccifer lacca Kerr.) was investigated [43]. Roselle colorant faded in the absence and presence of sodium dodecyl sulfate (SDS) and Tween 80 micelles.
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Lac colorant was quite stable with or without the surfactants. On the other hand, exceptional color fluctuation buffering effect was observed with anionic surfactant, especially SDS [44]. This was attributed to the effective shielding of anthocyanins from
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external acidity through strong interaction of SDS with positively charged flavylium
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cations owing to its anionic nature.
Microencapsulation of anthocyanins by spray drying with different natural biopolymers
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was used to develop natural colorants with high stability, solubility and dispersibility [45**]. Roberts and Freedes [46] reviewed the encapsulation of anthocyanins from
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twelve berry-type fruits to improve the stability and/or bioavailability of anthocyanins.
Engineered purple tomato was considered the best achievement so far in obtaining
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higher levels of anthocyanins via metabolic engineering [47]. In spite of progress in
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engineering anthocyanins in microorganisms, using plants and plant cell cultures to
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produce anthocyanin would be a more efficient strategy.
Betanin and chlorophylls
Betalains are subdivided into red-violet betacyanins and yellow-orange betaxanthins. Betanin is the most common betacyanin in the plant kingdom. For a long time beetroot had been considered the sole source of betanin, and dehydrated beets (beet powder) is the only betanin-containing approved color additive in the FDA list [37]. It is not surprising, therefore, that work on this pigment in recent years has been dominated by the search for other sources, such as Ulluco (Ullucus tuberosus), one of the most widely grown and economically important root crops in the Andean region of South America [48], and Basella rubra, commonly known as Malabar spinach, a leafy vegetable that
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accumulates pigments in its fruits [´49]. In the latter, total betalain content increased rapidly from early (green) through intermediate (half-done red-violet) to matured stage (red-violet). The pigment-rich fruit extract was used as natural colorant in ice-cream.
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After six months of storage at −20 °C, 87 % color was retained in the ice-cream.
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The most studied potential source is cactus pear (Opuntia ficus-indica). A natural extract was encapsulated by the PGSS® (Particles from Gas Saturated Solutions)
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technique into glyceryl monoostearate, using a surfactant (polyglyceryl-3
polyricinoleate) and water under different process conditions [50]. When compared with
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the Opuntia dried extract, lipidic particles contributed to a better homogenization of the
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pink colour after incorporation in ice cream. In another study, an extract was encapsulated with maltodextrin and cladode mucilage and only with maltodextrin [51].
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The addition of cladode mucilage increased the encapsulation efficiency, reduced the
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dietary fiber content.
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moisture content and resulted in more uniform size and spherical particles, with high
Pulp and ultrafiltered cactus pear extracts were encapsulated with Capsul by spraydrying [52]. Betacyanin and betaxanthin encapsulation efficiency reached values above 98% for both systems, this efficiency being attributed to strong interaction between betalains and the polymer. The betacyanin degradation rate constant was significantly higher for the encapsulated pulp than for the encapsulated ultrafiltered extract, suggesting that the mucilage or higher sugar content of the former increased the hygroscopicity of the microparticles, leading to the degradation of betalain. Hydrolysis (Figure 3) was the main mechanism for betanin degradation during storage of the microparticles.
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Khan and Giridhar [53*] estimated annual production potential of plant betalains from edible sources (red beetroot, Swiss chard petiole, cactus pear fruit, pitaya fruit and
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amaranth seed); production of beetroot far exceeded those of the other sources.
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Chlorophylls have been the least studied of the food pigments. Chlorophylls a and b were quantified along with carotenoids in pepper [10] and in apple [11]. Processing
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effects continue to be the focus of studies on these pigments (Figure 4). For example, microwave and conventional heating of kiwi led to 42–100% losses in the chlorophylls
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[54]. In some vegetables, high pressure treatment caused no degradation or slight
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increases, while high pressure high temperature degraded both chlorophylls [55]. Chlorophyll b was more stable than chlorophyll a at 70 °C, but both were highly
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degraded at 117 °C. In processed green olives, all the chlorophyll pigments were Mg-
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free (mostly pheophytins) [56]. In pistachio kernels, drastic losses were observed with pheophytins a and b, which both decreased by approximately 85% after 60 min of
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roasting [57]. Pyropheophytins a and b increased significantly during roasting and were 10–12 fold higher in the pistachios roasted for 60 min than in the raw pistachios.
Currently chlorophyll complexes and chlorophyllins are the only approved chlorophyll colorants [37]. Their use in food products is often limited by their susceptibility to photodegradation and instability in acidic pH (3.5-5).
Search for other colors Considerable effort has been devoted to the search for blue colorants. Newsome, Culver and van Breemen [58] reviewed known organic blue compounds from natural plant,
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animal and microbial sources. The scarcity of blue-colored metabolites in the natural world relative to metabolites of other colors is discussed, and structural trends common
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among natural blue compounds are identified.
Concluding remarks
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The great interest on the health benefits of natural pigments may have drawn attention
away from their coloring properties, but in the end is serving as a strong justification for
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their retention as natural constituents of foods during processing and storage and for their use as food and feed additives. Instability is a major problem, leading to such
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measures as microencapsulation and nanoencapsulation. Care must be taken, however,
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that such alterations do not take away the natural connotation, which is the other strong advantage of these pigments/colorants. The safety of the products should also be
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conclusively demonstrated.
References and recommended reading
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Papers of particular interest, published within the period of review, have been highlighted as:
*of special interest
**of outstanding interest
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21. Poojary MM, Passamonti P. Optimization of extraction of high purity all-
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trans-lycopene from tomato pulp waste. Food Chem 2015, 188:84-91.
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22. Poonkum W, Powtongsook S, Pavasant P: Astaxanthin induction in microalga H. pluvialis with flat panel airlift photobioreactors under indoor and
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types of tools and resources and further investigations.
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or determination of other components (e.g. major sugars, non-volatile organic
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acids, minerals, unsaturated fatty acids).
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31. **Jin AL, Ozga JA, Kennedy JA, Koerner-Smith JL, Botar G, Reinecke DM: Developmental profile of anthocyanin, flavonol, and proanthocyanidin type,
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This is another excellent example of a detailed study on fruits, in this case
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proanthocyanidins during fruit development and their localization in the fruits.
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42. Díaz-García MC, Castellar MR, Obón JM, Obón C, Alcaraz F, Rivera D: Production of an anthocyanin-rich food colourant from Thymus moroderi
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and its application in foods. J Sci Food Agric 2015, 95:1283–1293.
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This review gives updated information on the microencapsulation of anthocyanins by spray-drying, using natural biopolymers, including a
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49. Kumar SS, Manoj P, Shetty NP, Prakash M, Giridhar P: Characterization of major betalain pigments - gomphrenin, betanin and isobetanin from Basella
rubra L. fruit and evaluation of efficacy as a natural colourant in product (ice cream) development. J Food Sci Technol 2015, 52:4994-5002.
50. do Carmo CS, Nunes AN, Serra AT, Ferreira-Dias S, Nogueira I, Duarte CMM: A way to prepare a liposoluble natural pink colourant. Green Chem 2015, 17:1510-1518.
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51. Otálora MC, Carriazo JG, Iturriaga L, Nazareno MA, Osorio C: Microencapsulation of betalains obtained from cactus fruit (Opuntia ficusindica) by spray drying using cactus cladode mucilage and maltodextrin as
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encapsulating agents. Food Chem 2015, 187:174-181.
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52. Vergara C, Saavedra J, Sáenz C, García P, Robert P: Microencapsulation of pulp and ultrafiltered cactus pear (Opuntia fícus-indica) exracts and
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betanin stability during storage. Food Chem 2014, 157:246-251.
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Phytochemistry 2015, 117:267-295.
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53. *Khan MI, Giridhar P: Plant betalains: Chemistry and biochemistry.
This is a detailed review of the structures, occurrence, commercial production
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and biosynthesis of betalains.
54. Benlloch-Tinoco M, Kaulmann A, Corte-Real J, Rodrigo D, Martínez-Navarrete
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N, Torsten Bohn T: Chlorophylls and carotenoids of kiwifruit puree are affected similarly or less by microwave than by conventional heat processing and storage. Food Chem 2015, 187:254–262.
55. Sánchez C, Baranda AB, de Marañón IM: The effect of high pressure and high temperature processing on carotenoids and chlorophylls content in some vegetables. Food Chem 2014, 163:37-45.
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56. Ramírez E, Gandul-Rojas B, Romero C, Brenes M, Gallardo-Guerrero L: Composition of pigments and colour changes in green table olives related to
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processing type. Food Chem 2015, 166:115-124.
57. Pumilia G, Cichon MJ, Cooperstone JL, Giuffrida D, Dugo G, Schwartz SJ:
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Changes in chlorophylls, chlorophyll degradation products and lutein in pistachio kernels (Pistacia vera L.) during roasting. Food Res Int 2014,
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65:193-198.
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58. Newsome AG, Culver CA, van Breemen RB: Nature’s palette: The search for
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natural blue colorants. J Agric Food Chem, 2014, 62:6498–6511.
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Figure Captions Figure 1 The oxidative degradation of carotenoids involves isomerization and oxidation. Initially,
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a part of the all-E-carotenoids, the usual configuration in nature, is isomerized to the Zforms. Carotenoids in both forms are then oxidized, commencing with epoxidation,
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hydroxylation and cleavage to apocarotenals. Subsequent fragmentations result in a
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series of compounds of low molecular masses. Direct cleavage of the polyene chain to
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low mass compounds also appears to occur. Reproduced from Rodriguez-Amaya [18].
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Figure 2
It is widely known that anthocyanins can exist in different structural forms, depending
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on the pH. At pH 1-2, the red flavylium cation predominates. At pH 2-4, the blue
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quinoidal base is the dominant species. At pH 4-6, the colorless carbinol pseudobase
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prevails; towards pH 6, the pale yellow chalcone becomes the predominating species.
Figure 3
Under mild alkaline conditions, during heating of acidic solution or during thermal processing of beetroot, betanin degrades to the colorless cyclodopa-5-O-glucoside and and betalamic acid.
Figure 4
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Heat treatment of chlorophyll-containing foods results in the sequential conversion of chlorophylls (bright green color) to pheophytin and pyropheophytin (olive-brown). A similar reaction occurs in chlorophyllide, formed by the removal of phytol from
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chlorophyll, producing pheophorbide and pyropheophorbide.
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Figure 1 _____________________________________________________________________________
Fragmentation of polyene chain
heat, light, metals, pro-oxidant
volatile compounds
volatile compounds
Z -EPOXY Z -CAROTENOIDS Z -APOCAROTENOIDS HYDROXYCAROTENOIDS
LOW MASS VOLATILE COMPOUNDS
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ALL-E-EPOXY CAROTENOIDS ALL-EALL-E-HYDROXY APOCAROTENOIDS CAROTENOIDS
LOW MASS VOLATILE COMPOUNDS
O2
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O2
Fragmentation of polyene chain
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enzyme, heat, light, metals, pro-oxidantt
ZCAROTENOIDS
heat
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ALL- CAROTENOIDS E
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_____________________________________________________________________________ __________________________________________________
R1
R1
O+ R2
R2 OH
OH OH
OH
Red
OH
Carbinol pseudobase pH 4-5 Colorless
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Blue
H R2
OH
Flavylium cation pH 1-2
Quinoidal base pH 2-4
O
HO
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HO
O
OH OH
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O
R1 OH
OH
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_____________________________________________________________________________ __________________________________________________
28 Page 28 of 30
_____________________________________________________________________________ __________________________________________________ CH2O H
CH2O H
O O H
heat /
H O H
+ N
H O
CO O
H2O
- 2O H
-
H O
COO H
H
H O H
N+
H O
H
+
COO H
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N
O H
Cyclodopa- O5glucoside Colorless
H HOO C
H
O
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H O
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Betani n
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Red
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_____________________________________________________________________________ __________________________________________________
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HO C
_____________________________________________________________________________ C 2C O H heat
+
Chlorophyl l
Pheophyti n
acid/hea t
3
Pyropheophyti n
Mg 2
+
Pheophorbid e
acid/hea t
2C
H
3
Pyropheophorbid e
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Chlorophyllid e
C O
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chlorophyllas e Phyto l
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Mg 2
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S2214-7993(15)00104-6 http://dx.doi.org/doi:10.1016/j.cofs.2015.08.004 COFS 85
To appear in: Received date: Accepted date:
11-8-2015 13-8-2015
Please cite this article as: Rodriguez-Amaya, D.B.,Natural food pigments and colorants, COFS (2015), http://dx.doi.org/10.1016/j.cofs.2015.08.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Highlights
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Natural food pigments are actively studied because of potential health benefits. A diversity of plant and microbial sources has been reported. Processing effects have been widely investigated. Commercial production of natural colorants are still limited by instability Microencapsulation and nanoencapsulation are advocated to enhance stability
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DECLARATION 1 Page 1 of 30
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I, Delia B. Rodriguez-Amaya, sole author of the manuscript “Status of carotenoid analytical methods and in vitro assays for the assessment of food quality and health effects,” certify that this manuscript is the author’s original work, has not received prior publication and is not under consideration for publication elsewhere.
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Delia B. Rodriguez-Amaya
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June 1, 2014
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Natural food pigments and colorants
Delia B. Rodriguez-Amaya
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University of Campinas, Campinas, SP, BRAZIL
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E-mail: [email protected]
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Abstract
The natural color of foods is due primarily to carotenoids, anthocyanins, betanin and
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chlorophylls, either as inherent food constituents or as food or feed additives. These compounds have drawn considerable attention in recent years, not because of their
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coloring properties, but due to their potential health-promoting effects. Their occurrence
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and levels in foods, along with the factors that influence the composition, have been widely investigated. Processing effects have been actively studied. In spite of the
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intense search for plant and microbial sources and efforts to increase yield, few natural food color additives have reached the market. Lack of stability is a major deterrent; microencapsulation and nanoencapsulation are being advocated to minimize this problem.
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Introduction
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Foods, particularly fruits and vegetables, are naturally colored mainly by four groups of
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pigments: the green chlorophylls, the yellow-orange-red carotenoids, the red-bluepurple anthocyanins and the red betanin. These pigments are also incorporated into food
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products by direct addition or indirectly through animals’ feed. Although recent studies
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have been stimulated and dominated by their importance in human health, earlier
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investigations were motivated by the color they impart.
Employing natural colors is the current marketing trend because of consumers’ concern about the safety of artificial food dyes, reinforced by possible health benefits of the natural pigments. Replacement of the former by the latter, however, is challenging because natural colorants are usually less stable, more costly, are not as easily utilized as artificial colors, require more material to achieve equivalent color strength and has limited range of hues.
Motivated by potential health effects [1-6], literature on natural pigments, especially of carotenoids, is voluminous. Focusing on the last two years, research in Food Science in
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this area generally falls under the following topics: (a) composition and influencing factors (b) search for rich plant and microbial sources or increasing the pigment content, (c) assessing and improving stability and bioavailability, (d) processing effects and (e)
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health effects.
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Carotenoids
Determination of the carotenoid composition of foods continues to be actively pursued
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worldwide, attention being currently directed to indigenous and lesser known crops [e.g. 7-9]. Several countries have their own carotenoid databases, especially of the principal
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carotenoids in foods: β-carotene, α-carotene, β-cryptoxanthin, lycopene, lutein and
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zeaxanthin. Moreover, the different factors affecting the composition have been extensively investigated [e.g. 8, 9, 10-15], documenting the influence of
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cultivar/variety, stage of maturity, climate and season, farming practice and conditions,
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processing and storage. Since the physicochemical properties (e.g. color, solubility, stability), bioavailability and efficacy as health-promoting compounds differ among
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carotenoids, quantitative data have been obtained in terms of the concentrations of individual carotenoids, now often extended to separate quantification of E- and Z- (trans and cis) isomers.
In vitro assay of bioaccessibility has also been widely conducted with results mostly coherent with those of human studies on bioavailability, demonstrating the influence of dietary factors such as nature of the food matrix, carotenoid species and their geometric configuration, carotenoid-carotenoid interaction, amount and type of fat, amount and type of dietary fiber, other food constituents, food processing [e.g. 16, 17].
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Losses of carotenoids during the processing and storage of foods have been reported in numerous papers. However, knowledge of the reactions and the underlying mechanisms is still limited. There were attempts to elucidate degradation mechanisms in the 1980s,
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but such efforts had practically ceased when attention had been directed primarily to the health benefits of these pigments. Recent years have seen renewed interest on
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degradation, stimulated by the finding that the products can have negative or positive effects on human health. The major alterations undergone by the highly unsaturated
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carotenoids during processing and storage of foods are geometric isomerization and
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oxidation (Figure 1) [18].
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To date most of commercial carotenoids, used as food and feed additives and supplements, are products of chemical synthesis (e.g. β-carotene, astaxanthin,
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canthaxanthin and zeaxanthin), although they continue to be produced from a small
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microbial fermentation.
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number of rich natural sources (annatto, paprika, saffron, marigold, tomato) and by
Rich plant sources of carotenoids, such as the Asian gac (Momordica cochinchinensis Spreng.) fruit, are actively sought. Commercial products like gac powder and gac oil have been manufactured as natural colorants and medicinal supplements [19]. The extraction of natural pigment from Canna indica flowers using ultrasound resulted in significant improvement in extraction efficiency [20]. In line with current efforts to utilize industrial wastes, extraction of lycopene from the pulp fractions of tomato processing waste was optimized, resulting in 95% maximal recovery of high purity (98%) all-E-lycopene [21].
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In spite of the intense research on microbial carotenoid production, only three have reached commercial scale: β-carotene by the alga Dunaliella sp, astaxanthin by the alga Haematococcus pluvialis, and β-carotene by the fungus Blakeslea trispora. Research on
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optimization of conditions to increase carotenoid production by Haematoccus [e.g. 22,
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23] and investigation of other carotenoid producing microorganisms [e.g. 24] continue.
Advances in knowledge of the biosynthetic pathways, cloning of the genes that code the
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enzymes and availability of gene transfer techniques have led to genetic engineering in crop plants and in microorganisms to achieve higher content or better composition of
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carotenoids [e.g. 25]. Advantages of genetic engineering over conventional breeding
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include the ability to transfer genes in a faster and targeted manner. In addition to the transfer of genes from the same species, modern recombinant technologies permit the
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introduction of genetic material from diverse plants and unrelated species such as
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microorganisms. However, a lot more investigation and new tools/resources are deemed
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necessary to better reflect the dynamic nature of biosynthetic pathways [26*].
To address the stability problem, microencapsulation and nanoencapsulation have been investigated. Optimization of microencapsulation of gac oil by spray-drying resulted in a powder having high contents of lycopene and β-carotene and attractive red-yellow color [27]. Using four modified n-octenyl succinic anhydride (OSA)-starches, the best results were achieved with OSA starch refined from waxy maize [28]. Encapsulating crocin into chitosan-sodium alginate nanoparticles, prepared by a modified ionic gelation method, provided enhanced stability under unfavorable environmental conditions [29].
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Anthocyanins For anthocyanins, quantitative analysis has been widely done in terms of the total anthocyanin content. In recent years, however, an increasing number of papers report
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individual anthocyanin concentrations, and influencing factors have also been
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investigated [12, 30-34**].
It has been reported that the phenolic bioactive forms in vivo are not necessarily those
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which occur in foods, but rather conjugates or metabolites arising from them in the human body [35*]. Anthocyanins such as cyanidin-3-glucoside and pelargonidin-3-
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glucoside could be absorbed in their intact form into the gastrointestinal wall, undergo
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extensive first-pass metabolism and enter the systemic circulation as metabolites [36].
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The color of anthocyanins depends on the pH (Figure 2). Their stability is influenced by
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such factors as their structure and concentration, pH, temperature, light, oxygen,
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solvents, presence of enzymes, other flavonoids, proteins and metallic ions.
Utilization of anthocyanins as food colorants and functional ingredients has been limited because of their low stability and interaction with other compounds in the food matrix. The FDA list of color additives has only grape color extract and grape skin extract [37]. Thus, research has been directed towards the search for better sources and enhancement of extraction efficiency and stability, as exemplified by the following publications.
Among recognized good sources of anthocyanins are many berry-type fruits, red cabbage and purple sweet potato. Cultivar and maturation affected color and stability of
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red cabbage extracts at different pH [38]. Some varieties accumulated ≥30% of diacylated pigments, and monoacylated pigments decreased with time. Acylation is known to increase the anthocyanin’s stability. Purple-fleshed sweet potatoes P40 had
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high content of anthocyanins, of which cyanidin 3-p-hydroxybenzoylsophoroside-5-
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glucoside exhibited the best thermal stability [34].
Pulsed electric fields and ultrasonication were used as environmental friendly
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alternatives to water extraction at 70oC [39]. Both technologies were able to increase the extraction of anthocyanins in plum peels. In grape peels, ultrasonication was more
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effective. Pulse electric fields increased the extraction of anthocyanins from grape peels
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several fold. Ultrasound-assisted extraction was found to be a suitable technique for the extraction of anthocyanins from haskap berries [40]. The colorant powder obtained from
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black glutinous rice bran by ohmic heating-assisted extraction had higher colorant yield,
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anthocyanin pigments and bioactive compounds than conventional methods [41].
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A liquid concentrated colorant obtained from Thymus moroderi using water/citric acid as solvent was compared with two commercial anthocyanin-rich food colorants from red grape skin and red carrot (color strength of 1.7 and 3.6 AU, respectively) [42]. T. moroderi colourant had 1.2 AU color strength and high storage stability (>97% remaining color after 110 days at 4 °C). The colorant gave a stable pink color to yogurt during one month storage under refrigeration.
The stability in micellar solutions of extracts from roselle calyx (Hibiscus sabdariffa Linn.) and lac resin (Laccifer lacca Kerr.) was investigated [43]. Roselle colorant faded in the absence and presence of sodium dodecyl sulfate (SDS) and Tween 80 micelles.
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Lac colorant was quite stable with or without the surfactants. On the other hand, exceptional color fluctuation buffering effect was observed with anionic surfactant, especially SDS [44]. This was attributed to the effective shielding of anthocyanins from
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external acidity through strong interaction of SDS with positively charged flavylium
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cations owing to its anionic nature.
Microencapsulation of anthocyanins by spray drying with different natural biopolymers
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was used to develop natural colorants with high stability, solubility and dispersibility [45**]. Roberts and Freedes [46] reviewed the encapsulation of anthocyanins from
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twelve berry-type fruits to improve the stability and/or bioavailability of anthocyanins.
Engineered purple tomato was considered the best achievement so far in obtaining
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higher levels of anthocyanins via metabolic engineering [47]. In spite of progress in
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engineering anthocyanins in microorganisms, using plants and plant cell cultures to
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produce anthocyanin would be a more efficient strategy.
Betanin and chlorophylls
Betalains are subdivided into red-violet betacyanins and yellow-orange betaxanthins. Betanin is the most common betacyanin in the plant kingdom. For a long time beetroot had been considered the sole source of betanin, and dehydrated beets (beet powder) is the only betanin-containing approved color additive in the FDA list [37]. It is not surprising, therefore, that work on this pigment in recent years has been dominated by the search for other sources, such as Ulluco (Ullucus tuberosus), one of the most widely grown and economically important root crops in the Andean region of South America [48], and Basella rubra, commonly known as Malabar spinach, a leafy vegetable that
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accumulates pigments in its fruits [´49]. In the latter, total betalain content increased rapidly from early (green) through intermediate (half-done red-violet) to matured stage (red-violet). The pigment-rich fruit extract was used as natural colorant in ice-cream.
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After six months of storage at −20 °C, 87 % color was retained in the ice-cream.
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The most studied potential source is cactus pear (Opuntia ficus-indica). A natural extract was encapsulated by the PGSS® (Particles from Gas Saturated Solutions)
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technique into glyceryl monoostearate, using a surfactant (polyglyceryl-3
polyricinoleate) and water under different process conditions [50]. When compared with
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the Opuntia dried extract, lipidic particles contributed to a better homogenization of the
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pink colour after incorporation in ice cream. In another study, an extract was encapsulated with maltodextrin and cladode mucilage and only with maltodextrin [51].
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The addition of cladode mucilage increased the encapsulation efficiency, reduced the
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dietary fiber content.
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moisture content and resulted in more uniform size and spherical particles, with high
Pulp and ultrafiltered cactus pear extracts were encapsulated with Capsul by spraydrying [52]. Betacyanin and betaxanthin encapsulation efficiency reached values above 98% for both systems, this efficiency being attributed to strong interaction between betalains and the polymer. The betacyanin degradation rate constant was significantly higher for the encapsulated pulp than for the encapsulated ultrafiltered extract, suggesting that the mucilage or higher sugar content of the former increased the hygroscopicity of the microparticles, leading to the degradation of betalain. Hydrolysis (Figure 3) was the main mechanism for betanin degradation during storage of the microparticles.
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Khan and Giridhar [53*] estimated annual production potential of plant betalains from edible sources (red beetroot, Swiss chard petiole, cactus pear fruit, pitaya fruit and
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amaranth seed); production of beetroot far exceeded those of the other sources.
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Chlorophylls have been the least studied of the food pigments. Chlorophylls a and b were quantified along with carotenoids in pepper [10] and in apple [11]. Processing
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effects continue to be the focus of studies on these pigments (Figure 4). For example, microwave and conventional heating of kiwi led to 42–100% losses in the chlorophylls
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[54]. In some vegetables, high pressure treatment caused no degradation or slight
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increases, while high pressure high temperature degraded both chlorophylls [55]. Chlorophyll b was more stable than chlorophyll a at 70 °C, but both were highly
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degraded at 117 °C. In processed green olives, all the chlorophyll pigments were Mg-
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free (mostly pheophytins) [56]. In pistachio kernels, drastic losses were observed with pheophytins a and b, which both decreased by approximately 85% after 60 min of
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roasting [57]. Pyropheophytins a and b increased significantly during roasting and were 10–12 fold higher in the pistachios roasted for 60 min than in the raw pistachios.
Currently chlorophyll complexes and chlorophyllins are the only approved chlorophyll colorants [37]. Their use in food products is often limited by their susceptibility to photodegradation and instability in acidic pH (3.5-5).
Search for other colors Considerable effort has been devoted to the search for blue colorants. Newsome, Culver and van Breemen [58] reviewed known organic blue compounds from natural plant,
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animal and microbial sources. The scarcity of blue-colored metabolites in the natural world relative to metabolites of other colors is discussed, and structural trends common
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among natural blue compounds are identified.
Concluding remarks
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The great interest on the health benefits of natural pigments may have drawn attention
away from their coloring properties, but in the end is serving as a strong justification for
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their retention as natural constituents of foods during processing and storage and for their use as food and feed additives. Instability is a major problem, leading to such
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measures as microencapsulation and nanoencapsulation. Care must be taken, however,
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that such alterations do not take away the natural connotation, which is the other strong advantage of these pigments/colorants. The safety of the products should also be
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conclusively demonstrated.
References and recommended reading
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Papers of particular interest, published within the period of review, have been highlighted as:
*of special interest
**of outstanding interest
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3. De Pascual-Teresa S: Molecular mechanisms involved in the cardiovascular
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5. Esatbeyoglu T, Wagner AE, Schini-Kerth VB, Rimbach G: Betanin—A food
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colorant with biological activity. Mol Nutr Food Res 2015, 59:36–47.
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6. Nagini S, Palitti F, Natarajan AT: Chemopreventive potential of chlorophyllin:
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2015, 67:203-211.
7. Giuffrida D, Menchaca D, Dugo P, Donato P, Cacciola F, Murillo E. 2015. Study of the carotenoid composition in membrillo, guanabana toreta, jobo and mamey fruits. Fruits 2015, 70:163-172.
8. Wisutiamonkul A, Promdang S, Ketsa S, van Doorn WG: Carotenoids in durian fruit pulp during growth and postharvest ripening. Food Chem 2015, 180:301-305.
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9. Englberger L, Lorennij R, Taylor M, Tuia VS, Aalbersberg W, Dolodolotawake U, Tibon L, Tibon J, Alfred J: Carotenoid content and traditional knowledge of breadfruit cultivars of the Republic of the Marshall Islands. J Food
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Junguera V, Pérez-Martínez JD, Escalante-Minakata P: Antioxidant activity and content of chlorophylls and carotenoids in raw and heat-processed
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11. Delgado-Pelayo R, Gallardo-Guerrero L, Hornero-Méndez D: Chlorophyll and
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varieties. Food Res Int 2014, 65:272-281.
12. Kim HJ, Park, WS, Bae J-Y, Kang SY, Yang MH, Lee S, Lee H-S, Kwak S-S, Ahn M-J: Variations in the carotenoid and anthocyanin contents of Korean
cultural varieties and home-processed sweet potatoes. J Food Compos Anal 2015, 41:188-193.
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T, Hendrickx M, van Loey A: Color and carotenoid changes of pasteurized
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lipids: A review. Trends Food Sci Technol 2014, 38:125-135.
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19. Chuyen HV, Nguyen MH, Roach PD, Golding JB, Parks SE: Gac fruit (Momordica cochinchinensis Spreng.): a rich source of bioactive compounds
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and its potential health benefits. Int J Food Sci Technol 2015, 50:567–577.
20. Srivastava J, Vankar PS: Carotenoids: as natural food colorant from Canna
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21. Poojary MM, Passamonti P. Optimization of extraction of high purity all-
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trans-lycopene from tomato pulp waste. Food Chem 2015, 188:84-91.
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22. Poonkum W, Powtongsook S, Pavasant P: Astaxanthin induction in microalga H. pluvialis with flat panel airlift photobioreactors under indoor and
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autotrophic production from Haematococcus pluvialis under high temperature via heat stress-driven Haber-Weiss reaction. Appl Microbiol Biotechnol 2015, 99:5203-5215.
24. Muthezhilan R, Ragul R, Pushpam AC, Lakshmi Narayanan R, Jaffar Hussain A: Isolation, optimization and extraction of microbial pigments from marine yeast Rhodotorula Sp (Amby109) as food colourants. Biosci Biotechnol Res Asia 2014, 11:271-278.
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25. Campbell R, Morris WL, Mortimer CL, Misawa N, Ducreux LJM, Morris JA, Hedley PE, Fraser PD, Taylor MA: Optimising ketocarotenoid production in potato tubers: Effect of genetic background, transgene combinations and
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environment. Plant Sci 2015, 234:27-37.
in all dimensions. Plant Sci 2013, 208:58-63.
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26. *Shumskaya M, Wurtzel ET: The carotenoid biosynthetic pathway: Thinking
This is a cautious review of the possibilities of genetic engineering of the
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carotenoid biosynthetic pathway, emphasizing the need for developing new
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types of tools and resources and further investigations.
27. Kha TC, Nguyen MH, Roach PD, Stathopoulos CE: Microencapsulation of
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Gac oil: Optimisation of spray drying conditions using response surface
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methodology. Powder Tech 2014, 264:298-309.
28. De Paz E, Martín A, Bartolomé A, Largo M, Cocero MJ: Development of water-soluble β-carotene formulations by high-temperature, high-pressure emulsification and antisolvent precipitation. Food Hydrocoll 2014, 37:14-24.
29. Rahaiee S, Shojaosadati SA, Hashemi M, Moini S, Razavi SH. Improvement of crocin stability by biodegradable nanoparticles of chitosan-alginate. Int J Biol Macromol 2015, 79:423-432.
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30. **Brauch JE, Buchweitz M, Schweiggert RM, Carle R: Detailed analyses of fresh and dried maqui (Aristotelia chilensis (Mol.) Stuntz) berries and juice. Food Chem 2016, 190:308-316.
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This is a comprehensive study on the identification and quantification of individual anthocyanins in an underutilized fruit, along with characterization
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or determination of other components (e.g. major sugars, non-volatile organic
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acids, minerals, unsaturated fatty acids).
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31. **Jin AL, Ozga JA, Kennedy JA, Koerner-Smith JL, Botar G, Reinecke DM: Developmental profile of anthocyanin, flavonol, and proanthocyanidin type,
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content, and localization in Saskatoon fruits (Amelanchier alnifolia Nutt.). J Agric Food Chem 2015, 63:1601-1614.
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This is another excellent example of a detailed study on fruits, in this case
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involving the identification and quantification of anthocyanins, flavonols and
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proanthocyanidins during fruit development and their localization in the fruits.
32. Jorjong S,Butkhup L, Samappito S: Phytochemicals and antioxidant capacities of Mao-Luang (Antidesma bunius L.) cultivars from Northeastern Thailand. Food Chem 2015, 181:248-255.
33. Szalóki-Dorkó L, Stéger-Máté M, Abrankó L: Evaluation of colouring ability of main European elderberry (Sambucus nigra L.) varieties as potential resources of natural food colourants. Int J Food Sci Technol 2015, 50:1317– 1323.
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34. Xu J, Su X, Lim S, Griffin J, Carey E, Katz B, Tomich J, Smith JC, Wang W. Charaterization and stability of anthocyanins in purple-fleshed sweet
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potato P40. Food Chem 2015, 186:90-96.
35. *Fernandes I, Faria A, de Freitas V, Calhau C, Mateus N: Multiple-approach
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studies to assess anthocyanin bioavailability. Phytochem Rev 2015, doi:10.1007/s11101-015-9415-3.
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This review presents current knowledge on anthocyanin bioavailability,
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pointing out the lack of conclusive information on the underlying molecular
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mechanisms.
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36. Fang J: Bioavailability of anthocyanins. Drug Metab Rev 2014, 46:508-520.
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37. Code of Federal Regulations. 21 CFR Part 73 – Listing of color additives exempt from certification. US Food Drug Admin. Available at:
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http://www.fda.gov/ForIndustry/ColorAdditives/default.htm.
38. Ahmadiani N, Robbins RJ, Collins TM, Giusti MM: Anthocyanins contents, profiles, and color characteristics of red cabbage extracts from different cultivars and maturity stages. J Agric Food Chem 2014, 62:7524–7531.
39. Medina-Meza IG, Barbosa-Cánovas GV: Assisted extraction of bioactive compounds from plum and grape peels by ultrasonics and pulsed electric fields. J Food Eng 2015, 166:268-275.
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40. Celli GB, Ghanen A, Brooks MS-L: Optimization of ultrasound-assisted extraction of anthocyanins from haskap berries (Lonicera caerulea L.) using
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response surface methodology. Ultrason Sonochem 2015, 27:449-455.
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41. Loypimai P, Moongngarm A, Chottanom P, Moontree T: Ohmic heatingassisted extraction of anthocyanins from black rice bran to prepare a
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natural food colourant. Innov Food Sci Emerg Technol 2015, 27:102-110.
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42. Díaz-García MC, Castellar MR, Obón JM, Obón C, Alcaraz F, Rivera D: Production of an anthocyanin-rich food colourant from Thymus moroderi
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and its application in foods. J Sci Food Agric 2015, 95:1283–1293.
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43. Piyarat K, Walaisiri M, Pornpen W: Comparison of stability of red colorants
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21:325-330.
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from natural sources, roselle and lac in micelles. Int Food Res J 2014,
44. Liu S, Fu Y, Nian S. Buffering colour fluctuation of purple sweet potato anthocyanins to acidity variation by surfactants. Food Chem 2014, 162:16-
21.
45. **Mahdavi SA, Jafari SM, Ghorbani M: Spray-drying microencapsulation of anthocyanins by natural biopolymers: A review. Dry Technol 2014, 32:509518.
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This review gives updated information on the microencapsulation of anthocyanins by spray-drying, using natural biopolymers, including a
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discussion of optimized conditions and effectiveness.
46. Robert P, Freedes C: The encapsulation of anthocyanins from berry-type
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fruits. Molecules 2015, 20:5875-5888.
47. Zhang Y, Butelli E, Martin C: Engineering anthocyanin biosynthesis in
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plants. Curr Opin Plant Biol 2014, 19:81-90.
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48. Cejudo-Bastante MJ, Hurtado N, Mosquera N, Heredia FJ: Potential use of new Colombian sources of betalains. Color stability of ulluco (Ullucus tuberosus)
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extracts under different pH and thermal conditions. Food Res Int 2014,
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64:465-471.
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49. Kumar SS, Manoj P, Shetty NP, Prakash M, Giridhar P: Characterization of major betalain pigments - gomphrenin, betanin and isobetanin from Basella
rubra L. fruit and evaluation of efficacy as a natural colourant in product (ice cream) development. J Food Sci Technol 2015, 52:4994-5002.
50. do Carmo CS, Nunes AN, Serra AT, Ferreira-Dias S, Nogueira I, Duarte CMM: A way to prepare a liposoluble natural pink colourant. Green Chem 2015, 17:1510-1518.
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51. Otálora MC, Carriazo JG, Iturriaga L, Nazareno MA, Osorio C: Microencapsulation of betalains obtained from cactus fruit (Opuntia ficusindica) by spray drying using cactus cladode mucilage and maltodextrin as
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encapsulating agents. Food Chem 2015, 187:174-181.
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52. Vergara C, Saavedra J, Sáenz C, García P, Robert P: Microencapsulation of pulp and ultrafiltered cactus pear (Opuntia fícus-indica) exracts and
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betanin stability during storage. Food Chem 2014, 157:246-251.
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Phytochemistry 2015, 117:267-295.
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53. *Khan MI, Giridhar P: Plant betalains: Chemistry and biochemistry.
This is a detailed review of the structures, occurrence, commercial production
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and biosynthesis of betalains.
54. Benlloch-Tinoco M, Kaulmann A, Corte-Real J, Rodrigo D, Martínez-Navarrete
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N, Torsten Bohn T: Chlorophylls and carotenoids of kiwifruit puree are affected similarly or less by microwave than by conventional heat processing and storage. Food Chem 2015, 187:254–262.
55. Sánchez C, Baranda AB, de Marañón IM: The effect of high pressure and high temperature processing on carotenoids and chlorophylls content in some vegetables. Food Chem 2014, 163:37-45.
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56. Ramírez E, Gandul-Rojas B, Romero C, Brenes M, Gallardo-Guerrero L: Composition of pigments and colour changes in green table olives related to
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processing type. Food Chem 2015, 166:115-124.
57. Pumilia G, Cichon MJ, Cooperstone JL, Giuffrida D, Dugo G, Schwartz SJ:
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Changes in chlorophylls, chlorophyll degradation products and lutein in pistachio kernels (Pistacia vera L.) during roasting. Food Res Int 2014,
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65:193-198.
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58. Newsome AG, Culver CA, van Breemen RB: Nature’s palette: The search for
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natural blue colorants. J Agric Food Chem, 2014, 62:6498–6511.
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Figure Captions Figure 1 The oxidative degradation of carotenoids involves isomerization and oxidation. Initially,
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a part of the all-E-carotenoids, the usual configuration in nature, is isomerized to the Zforms. Carotenoids in both forms are then oxidized, commencing with epoxidation,
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hydroxylation and cleavage to apocarotenals. Subsequent fragmentations result in a
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series of compounds of low molecular masses. Direct cleavage of the polyene chain to
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low mass compounds also appears to occur. Reproduced from Rodriguez-Amaya [18].
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Figure 2
It is widely known that anthocyanins can exist in different structural forms, depending
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on the pH. At pH 1-2, the red flavylium cation predominates. At pH 2-4, the blue
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quinoidal base is the dominant species. At pH 4-6, the colorless carbinol pseudobase
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prevails; towards pH 6, the pale yellow chalcone becomes the predominating species.
Figure 3
Under mild alkaline conditions, during heating of acidic solution or during thermal processing of beetroot, betanin degrades to the colorless cyclodopa-5-O-glucoside and and betalamic acid.
Figure 4
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Heat treatment of chlorophyll-containing foods results in the sequential conversion of chlorophylls (bright green color) to pheophytin and pyropheophytin (olive-brown). A similar reaction occurs in chlorophyllide, formed by the removal of phytol from
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chlorophyll, producing pheophorbide and pyropheophorbide.
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Figure 1 _____________________________________________________________________________
Fragmentation of polyene chain
heat, light, metals, pro-oxidant
volatile compounds
volatile compounds
Z -EPOXY Z -CAROTENOIDS Z -APOCAROTENOIDS HYDROXYCAROTENOIDS
LOW MASS VOLATILE COMPOUNDS
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ALL-E-EPOXY CAROTENOIDS ALL-EALL-E-HYDROXY APOCAROTENOIDS CAROTENOIDS
LOW MASS VOLATILE COMPOUNDS
O2
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O2
Fragmentation of polyene chain
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enzyme, heat, light, metals, pro-oxidantt
ZCAROTENOIDS
heat
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ALL- CAROTENOIDS E
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_____________________________________________________________________________ __________________________________________________
R1
R1
O+ R2
R2 OH
OH OH
OH
Red
OH
Carbinol pseudobase pH 4-5 Colorless
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Blue
H R2
OH
Flavylium cation pH 1-2
Quinoidal base pH 2-4
O
HO
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HO
O
OH OH
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O
R1 OH
OH
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_____________________________________________________________________________ __________________________________________________
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_____________________________________________________________________________ __________________________________________________ CH2O H
CH2O H
O O H
heat /
H O H
+ N
H O
CO O
H2O
- 2O H
-
H O
COO H
H
H O H
N+
H O
H
+
COO H
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N
O H
Cyclodopa- O5glucoside Colorless
H HOO C
H
O
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H O
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Betani n
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Red
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_____________________________________________________________________________ __________________________________________________
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HO C
_____________________________________________________________________________ C 2C O H heat
+
Chlorophyl l
Pheophyti n
acid/hea t
3
Pyropheophyti n
Mg 2
+
Pheophorbid e
acid/hea t
2C
H
3
Pyropheophorbid e
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Chlorophyllid e
C O
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chlorophyllas e Phyto l
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Mg 2
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_____________________________________________________________________________
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