Spectral properties of different forms of several vitisin-type pigments, recently found in red wines and grapes, were studied. These orange-red tone compounds seem to be promising anthocyanin based food colors

Dragan Amić

Drago Bešlo

Dušanka Davidović-Amić

Nenad Trinajstić

English

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ISSN-0011-1643CCA-2662 NoteVitisin-Type Pigments: Possible Novel Food ColorsDragan Ami},a,* Du{anka Davidovi}-Ami},a Drago Be{lo,aand Nenad Trinajsti}baFaculty of Agriculture, The Josip Juraj Strossmayer University, P. O. Box 719,HR–31001 Osijek, The Republic of CroatiabThe Rugjer Bo{kovi} Institute, P. O. Box 180, HR–10002 Zagreb,The Republic of CroatiaReceived June 28, 1999; revised December 14, 1999; accepted December 15, 1999Spectral properties of different forms of several vitisin-type pig-ments, recently found in red wines and grapes, were studied. Theseorange-red tone compounds seem to be promising anthocyaninbased food colors.Key words: vitisin-type pigments, wine pigments, food colorsINTRODUCTIONThere is worldwide interest in using food colorants from natural sourcesto replace artificial colorants.1 Anthocyanins are the largest group of water-soluble natural pigments that have been used with some commercial suc-cess.2 Anthocyanins are responsible for most of the red, purple, and blue col-ors exhibited by flowers, fruits, and other plant tissues.3 However, they usu-ally incur the disadvantages of color instability, spontaneous degradationand conversion to uncolored forms under heat, light, and moderate pH.4Many efforts have been made to search for highly stable anthocyaninsfrom fruit, vegetables, or ornamental plants, and to improve the stability ofanthocyanins.5 Production of anthocyanins from cell cultures has been in-vestigated.6 Also, there is the current medical interest in anthocyanins: forexample, anthocyanins possess potent antioxidant properties.7 The presence* Author to whom correspondence should be addressed. (E-mail: damic@suncokret.pfos.hr)CROATICA CHEMICA ACTA CCACAA 73 (2) 511¿516 (2000)of significant amounts of anthocyanins in red grapes and wines contributesto their powerful antioxidative activity. A famous phenomenon associatedwith anthocyanins is the so-called »French Paradox«. Moderate consump-tion of red wines by the French could provide an explanation for the low car-diovascular disease mortality rate encountered in that country.8Anthocyanins are important constituents of grapes and red wines. Theyare the main compounds involved in the color of red wine.9 A large numberof potential sources of anthocyanins have been suggested as potential foodcolorants. The oldest and most abundant anthocyanin extract is »enocian-ina« or enocyanin, produced from red grape pomace, which has found appli-cation as a general food colorant.10 HPLC analyses of fortified red wines re-vealed, in small quantities, new anthocyanin-derived red pigments.11 Ano-ther related red wine pigment has been found recently.12The purpose of this study was to evaluate the spectral characteristics ofthe aglycones of new red wine pigments in an attempt to optimize utiliza-tion of naturally occurring colorants from grapes and wine. Calculations ofelectronic absorption spectra were carried out using the PPP method.13VITISIN-TYPE PIGMENTSMalvidin-type anthocyanins are the prevailing anthocyanins in red winemade from Vitis vinifera grapes. During the conservation and aging of redwines, formation of new pigments occurs as a result of the interaction be-tween anthocyanins and other products extracted from grapes. If aging goeson for long periods, colored precipitates appear. Malvidin-type pigments, vi-tisin A and vitisin B, were found in small amounts in some red wines and attrace levels in stored grapes.14,15 The structure of another red wine pigmenthas been published recently.16 In grapes and wines, the vitisins are in thered flavylium form AH+. Like common anthocyanins, as the pH is raised,they may form the blue-purple quinoidal-base (A-7 and/or A-4'), the color-less carbinol pseudo-base B, and the pale yellow or colorless chalcone C. Theproposed structural transformations of vitisidin A (the aglycone of vitisinA),17 which match exactly those of anthocyanins, are presented in Figure 1.Spectral characteristics of vitisidin A, vitisidin B, and the aglycone ofthe related malvidin-derived wine pigment were evaluated. Structures ofthese pigments as well as the corresponding calculated absorption maximain UV/VIS spectra max (in nm) are presented in Figure 2.All the studied pigments possess a malvidin substitution pattern. Due tosubstituted C-4 position, absorption maxima of their acidic AH+ form exhi-bit hypsochromic spectral shifts from malvidin 3-glucoside, and thus giverise to the orange hue of red coloration. Flavylium structure AH+ dominatesto approximately pH 5, while at nearly neutral pH the other dominant form512 D. AMI] ET AL.is the quinoidal-base A, which itself is bluish-red in color. As mentioned inthe literature,18 the quinoidal-base form of malvidin pigment is mainly ofA-4' form. Thus, slightly acidic and neutral solutions of vitisidins should bepreferably red colored.Three decades ago it was shown that the pigments of aged red wine aremore stable than the anthocyanins themselves.19 The presence of substitu-ent at C-5, and in particular substitution at C-4 in vitisidins, both stabilizethe colored forms (AH+ and A), i.e. protect the molecule from hydration,which usually leads to the colorless carbinol pseudo-base B.20 C-4 substitu-tion should also give rise to resistance of vitisidins to color bleaching by sul-phur dioxide. Considering that SO2 is widely used in food products, it is adesirable property. A very recent publication reported that vitisin-type pig-ments express much more color than the common anthocyanins.21The pathway for the formation of vitisidin-type compounds seems to in-volve reactions between synthetic aglycones of anthocyanins or relatedflavylium salts with naturally occurring constituents in grapes and wines.These reactions could be guided by calculation of UV/VIS spectra of the pro-VITISIN-TYPE PIGMENTS 513HOHOOHOOCH3OHOCH3OHOHOOHOOCH3OHOCH3HO O+HOHOOHOOCH3OCH3HO OOOHOHOOHOOCH3OHOCH3HO OHOHOOHOCH3OHOCH3HOOHOOHHOHOH+ H++ H2O / H++ H2OA-7 AH+ A-4'BC234567Figure 1. Proposed structural transformations of vitisidin A.posed vitisidin-type analogue. A structure with desirable spectral propertiescould be consequently synthesized. It will be interesting to see if some fu-ture experimental work should support this reasoning.514 D. AMI] ET AL.Aglycone ofanthocyanin-derivedwine pigmentElectronic spectraaAH+ form A-7 form A-4' formmax f max f max fnm nm nm509.4 0.817381.5 0.064346.6 0.515563.2 0.775396.8 0.511376.9 0.142558.6 1.537406.6 0.002382.8 0.033486.2 1.121380.1 0.086337.6 0.028539.0 0.668419.4 0.339354.1 0.163545.0 1.994401.6 0.002382.9 0.025508.0 1.273392.0 0.352351.1 0.320544.2 0.648454.6 0.872346.7 0.619584.3 2.207402.8 0.016399.6 0.019aCalculated by PPP method.Figure 2. Absorption spectra of the studied anthocyanin-derived wine pigments. Cal-culated absorption maxima in UV/VIS spectra max (nm) and the corresponding os-cillator strengths (f).Related winepigmentCONCLUSIONMolecular features of the studied aglycones of new wine pigments, vitis-idins, could overcome the well known shortcomings of anthocyanins as foodcolorants. Their desirable color and stability properties suggest that theymay be appropriate for many food applications (as natural alternatives toartificial colorants). Further work is required to elucidate the chemical na-ture of the individual red wine pigments, and the mechanisms of their for-mation during vinification. This is of interest as a potential method forlarge-scale production of vitisin-type pigments.Acknowledgements. – This work was supported in part by Grants 079301 (D. A.,D. D. A., D. B.) and 00980606 (N. T.) awarded by the Ministry of Science and Techno-logy of the Republic of Croatia.REFERENCES1. C. F. Timberlake and B. S. Henry, Anthocyanins as Natural Food Colorants, in: V.Cody, E. Middleton, Jr., J. B. Harborne, and A. Beretz (Eds.), Plant Flavonoids inBiology and Medicine II: Biochemical, Cellular and Medicinal Properties, Alan R.Liss, New York, 1988.2. F. J. Francis, Crit. Rev. Food Sci. Nutr. 28 (1989) 273–314.3. J. B. Harborne, Comparative Biochemistry of the Flavonoids, Academic Press,New York and London, 1967.4. P. Markakis (Ed.), Anthocyanins as Food Colors, Academic Press, New York, 1982.5. For a review, see: P. Bridle and C. F. Timberlake, Food Chem. 58 (1997) 103–109.6. D. L. Madhavi, S. Juthangkoon, K. Lewen, M. D. Berber-Jimenez, and M. A. L.Smith, J. Agric. Food Chem. 44 (1996) 1170–1176, and the references cited therein.7. For example, see : (a) H. Tamura and A. Yamagami, J. Agric. Food Chem. 42(1994) 1612–1615; (b) H. Wang, G. Cao, and R. L. Prior, J. Agric. Food Chem. 45(1997) 304–309; (c) M. T. Satue-Gracia, M. Heinonen, and E. N. Frankel, J. Agric.Food Chem. 45 (1997) 3362–3367; (d) T. Lapidot, S. Harel, B. Akiri, R. Granit, andJ. Kanner, J. Agric. Food Chem. 47 (1999) 67–70; (e) H. Wang, M. G. Nair, G. M.Strasburg, Y.-C. Chang, A. M. Booren, J. I. Gray, and D. L. DeWitt, J. Nat. Prod.62 (1999) 294–296.8. (a) S. Renaud and M. de Lorgeril, Lancet 339 (1992) 1523–1526; (b) R. Brouillard,F. George, and A. Fougerousse, BioFactors 6 (1997) 403–410; (c) A. Ghiselli, M.Nardini, A. Baldi, and C. Scaccini, J. Agric. Food Chem. 46 (1998) 361–367.9. P. Ribereau-Gayon, The Anthocyanins of Grapes and Wines, in: P. Markakis (Ed.),Anthocyanins as Food Colors, Academic Press, New York, 1982.10. G. Mazza, Crit. Rev. Food Sci. Nutr. 35 (1995) 341–371.11. J. Bakker, Studies on the Colors and Pigments of Port Wines. Ph. D. Thesis, Uni-versity of Bristol, U. K., 1985.12. P. J. Cameira-dos-Santos, V. Cheynier, J. M. Brillouet, and M. Moutounet, Poly-phenols Communications (1996) 51–52.13. For details, see : D. Davidovi}-Ami}, D. Ami}, and N. Trinajsti}, Croat. Chem.Acta 67 (1994) 163–170.VITISIN-TYPE PIGMENTS 51514. J. Bakker, P. Bridle, T. Honda, H. Kuwano, N. Saito, N. Terahara, and C. F. Tim-berlake, Phytochemistry 44 (1997) 1375–1382.15. J. Bakker and C. F. Timberlake, J. Agric. Food Chem. 45 (1997) 35–43.16. H. Fulcrand, P. J. Cameira-dos-Santos, P. Sarni-Manchado, V. Cheynier, and J.Favre-Bonvin, J. Chem. Soc., Perkin Trans. 1 (1996) 735–739.17. Fulcrand et al. recently reported slightly different structure of vitisin A. See : H.Fulcrand, C. Benabdeljalil, J. Rigaud, V. Cheynier, and M. Moutounet, Phytoche-mistry 47 (1998) 1401–1407.18. K. Abe, Y. Sakaino, J.-I. Kakinuma, and H. Kakisawa, Nippon Kagaku Kaishi(1977) 1197–1204.19. T. C. Somers, Phytochemistry 10 (1971) 2175–2186.20. R. Brouillard, G. A. Iacobucci, and J. G. Sweeny, J. Am. Chem. Soc. 104 (1982)7585–7590.21. C. Romero and J. Bakker, J. Agric. Food Chem. 47 (1999) 3130–3139.SA@ETAKPigmenti tipa vitisina: mogu}a nova prehrambena bojilaDragan Ami}, Du{anka Davidovi}-Ami}, Drago Be{lo i Nenad Trinajsti}Prou~avane su spektralne osobine razli~itih oblika nekoliko pigmenata tipa viti-sina, nedavno detektiranih u vinu i gro`|u. Ti naran~astocrveni spojevi antocijani-dinske strukture mogu se pokazati potencijalno upotrebljivima kao bojila za hranu.516 D. AMI] ET AL.

Vitisin-Type Pigments: Possible Novel Food Colors

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