Research NoteThe effect of caffeic acid and SO, on the interaction between malvidin 3-glucoside, (+)-catechin and acetaldehyde was investigated in model wine systems. Reactions were monitored by HPLC, spectrophotometry and tristimulus colorimetry. Caffeic acid had only a marginal effect on the reactions involving the other components in these model wine solutions

Bakker, Johanna

Bridle, P.

Garcia-Viguera, C.

Picinelli, A.

English

JKI Open Journal Systems (Julius Kühn-Institut)

Vitis 34 (1) , 69-70 (1995) Research Note Model wine solutions: Caffeic acid is not an important factor in colour and composition changes during red wine aging JoHANNA BAKKER, A. PICINELLI, P. BRIDLE and c. GARCIA-VIGUERA. S u m m a r y : The effect of caffeic acid and SO on the interaction between malvidin 3-glucoside, (+)-catechin and acetaldehyde was investigated in model wine systems. Reactions were monitored by HPLC, spectrophotometry and tristimulus colorimetry. Caffeic acid had only a marginal effect on the reac-tions involving the other components in these model wine solu-tions. Key w o r d s : model wines, anthocyanins, acetaldehyde, catechin, S02, caffeic acid, HPLC, colour measurements. Introduction: Caffeic acid and its derivatives (e .g. trans-caffeoyltartaric acid and chlorogenic acid) are known to have an important role in the enzyrnic and the non-enzymic oxidative browning reactions in white wines and also during the first stages of oxidative browning in grape musts (CHEYNTER et al. 1988; CILLIERS and SINGLETON 1989; CILLIERS and SINGLETON 1990 a; CHEYNIER and MouTOUNET 1992). In studies using both caffeoyltartaric acid (caftaric acid) and caffeic acid, the non-enzymic reaction was en-hanced, both at pHs approaching neutrality and at higher temperatures (CILLIERS and SINGLETON 1989, 1990 a), al-though slow oxidation of caffeic acid was observed at pH 4 . Thiols, such as gluthatione, increase oxygen uptake in com-bination with o-dihydroxyphenols (CILLI ERS and SINGLETON 1990 b) and can also react rapidly with caftaric acid quinones, to yield 2-S-glutathionylcaffeic acid. After depletion of thiols, the caftaric o-quinones oxidise other phenolic compounds (CH EYN IER and MouTOUNET 1992). Hence once caftaric quinones have been formed , enzymi-cally or non-enzymically, they can induce coupled oxida-tion of catechin to catechin a-quinone, which in turn, re-acts rapidly with hydroquinones to form condensation prod-ucts (CHEYNIER et al. 1989). Caffeic acid is an important non-flavonoid phenolic constituent in wines , reported as occuning at levels of ea. 5 mg/1 ~MERINE and OuGH 1980), although we have found up to 37 mg/1 in red wines analysed in our labora-tory. Research has focused on the effect of caffeic acid on oxidation and browning of white wines or white wine models, but there appear to be no studies on the possible interaction of caffeic acid in condensation reactions oc-curring in model red wine solutions. Hence, it was of in-terest to investigate any additional effect produced by Institute of Food Research, Reading Laboratory, Reading, UK. ' Permanent add ress: CEBAS-CSIC Apdo Correo s , E-30080 Murcia, Spain caffeic acid in the presence of some principal contributors to red wine colour, malvidin 3-glucoside, (+)-catechin and acetalde-hyde. The possible inhibitory effect of SO, on these reactions in red wines was also considered. -Materials and methods: All materials were obtained commercially, except for malvidin 3-glucoside which was isolated and purified in our laboratory by semi-prepara-tive HPLC of a Vitis vinifera grape skin extract. Model solution components were dissolved in a sterilised wine medium of potassium bitartrate (0.02 M, pH 3.7) containing ethanol (10 % v/v) to give the follow-ing final concentrations: malvidin-3-glucoside 0.21 mM (0.11 mg/rnl) , (+)-catechin 0.53 mM (0.15 mg/rnl) , cafeic acid 0 .53 mM (0 . 10 mg/ml) , acetaldehyde 0 .90 mM (0.04 mg/ml) and using sodium metabisulphite solutions, S02 0 .90 mM (0.06 mg/rnl). Diferent experimental mix-tures were prepared, filtred (0.45 !J.m sterile membrane fil-ters) and kept in screw-top vials as follows : M: malvidin-3-glucoside (control) , MC : malvidin-3-glucoside and (+)-catechin, MF: malvidin-3-glucoside and caffeic acid, MCA: malvidin-3-glucoside, (+)-catechin and acetalde-hyde, MCF: malvidin-3-glucoside, (+)-catechin and caffeic acid, MCS: malvidin-3-glucoside, (+)-catechin and SO, , MFA: malvidin-3-glucoside, caffeic acid and acetaldehyde, MFS: malvidin-3-glucoside, caffeic acid and SO,, MCFAS: malvidin-3-glucoside, (+)-catechin, caffeic acid-, acetalde-hyde and S02• All the samples were allowed to react in the dark at room temperature and were analysed in duplicate over a period of 150 d. Changes in the colour and composition of the test so-lutions were followed using HPLC, spectrophotometry and tristimulus colour measurements (CIELAB 76) (B AKKER et al. 1993). so2 (free and total) was measured by ion chro-matography and total acetaldehyde was determined enzymatically. Results and discussion: Results reported previously in the absence of caffeic acid (PICLNELLI et al. 1994) were confirmed in this work, and comments are made here only on changes in solutions containing caffeic acid. The caffeic acid concentration in solutions MF, MCF, MFA and MFS did not change significantly during 150 d, indicating that if caffeic acid quinones had been formed , they would have oxidised the catechin or malvidin 3-glucoside by coupled oxidation, and themselves revert back to hydroquinones. Coupled oxidation of caffeoyltar-taric acid o-quinones with catechin has been reported pre-viously (CHEYNTER et al. 1989). Fig. 1 shows that catechin and caffeic acid both indi-vidually increase the rate of loss of malvidin 3-glucoside. The loss of malvidin 3-glucoside was only marginally faster in model MF compared to M , indicating the caffeic acid did not have a significant oxidative effect on malvidin 3-glucoside. The loss of malvidin 3-glucoside in MCF was marginally faster than in model MC, indicating a possible coupled oxidation of caffeic acid with catechin under these conditions, thus enhancing the anthocyanin loss . 70 JoHAN NA BAKKER, A. PICI NELLI , P. BRIDLE and C. GARCIA-YIGUERA ~ ..... l u ::! ~ 0 u ~ ~ C') .:! 'd ~ 100 80 60 40 -i:l- M ······•····· MC ···"Ill··· MF .:~ ···•-- MCF ''::::~::::;;::::-:<~:~;~~· · ·. ''I······A The formation of two new wine pigments A and B after 29 d (GARCIA-YIGUERA et al. 1994) was delayed in the presence of caffeic acid and S02 (MCFAS). Pigment B appeared after 54 d and A after 137 d. Compounds analo-gous to A and B formed from caffeic acid , instead of catechin, are unlikely to be found , since a centre of net negative charge is not feasible on the caffeic acid mol-ecule. Caffeic acid quinones formed would only be ex-pected to oxidise the catechin present, by coupled oxida-tion, and possibly be involved in the formation of conden-sation products (CHEYNIER et al. 1989). 20 0 0 100 ,, -.. Caffeic acid had no additional effect on the colour quality, expressed as hue angle and chroma, of the malvidin control or on the rate of browning of malvidin 3-glucoside 200 with catechin (data not shown). Days Fig. 1: Loss of malvidin 3-glucoside in solutions M, MC, MF and MCF (Abbreviations see "Materials and methods"). Fig. 2 shows that S02 reduces the loss of malvidin 3-glucoside in the presence of the caffeic acid, e.g., compare MF with MFS. The smaller loss of malvidin 3-glucoside in MCS compared to MC agrees with our previous data (PICINELLI et al. 1994). The presence of acetaldehyde (MFA) increases the loss of mal vi din 3-glucoside compared to MF, possibly due to a reaction of acetaldehyde with malvidin 3-glucoside. 120 -·-lt·· MCA -..... - MCS 100 ~RQ,~·-·"'· ·11:---·-MFA ~ ........ , -....... , •••• •· O····· MFS l ..... ', ······•····· MC 80 ........... .... ... ---"1!1··· MF ""-. ', u \l< ' "' ~ \ ........ ', 0 '\, '~---. ... "\ u 60 ~ ~ 40 \ ...•.. ·:::::·: ....... ~ 20 .,..,.1( 0 0 100 200 Days Fig. 2: Loss of mal vi din 3-glucoside in solutions MC, MF, MCA, MCS , MFA and MFS (Abbreviations see "Materials and methods"). P. BRIDLE and J. B AKKER wish to thank the EC for funding this project under FLAIR (project no. 89053). C. G ARCIA-VIGUERA is indebted to the Consejo Superior de Investigaciones Cientificas for a grant and A. PICINELLI is indebted to NATO's Scientific Com-mittee, Spain, for financial support. AMERINE, M. A. ; OUGH, C. S. ; 1980: Phenolic Compounds. In: AMERINE, M. A.; 0 UGH, C. S. (Eds.): Methods for Analysis of Musts and Wines, 175-199. BAKKER, J. ; PICINELLI , A. ; BRIDLE, P. ; 1993: Model wine solutions: Color and composition changes during ageing. Vitis 32, 111-118. CHEYNIER , V.; BAS IR E, N.; RIGA UD, J.; 1989: Mechani sm of II'OII S-caffeoyltartaric acid and catechin oxidation in model so lutions con-taining grape polyphenol oxidase. J. Agricult. Food Chem. 37, 1069-1071. - -; MouTOUNET, M. ; 1992: Oxidative reactions of caffeic acid in model systems containing polyphenol oxidase. J. Agricull. Food Chem. 40, 2038-2044. - -; OssE, C.; RIGAUD, J.; 1988: Oxidation of grape juice phenolic com-pounds in model so lutions. J. Food Sci. 53, 1729-1732, 1760. CiLUERS, J. J. L.; SINGLETON, V. L.; 1989: Non-enzymic autoxidative phe-nolic browning reaction in a caffeic ac id model system. J. Agricult. Food Chem. 37, 890-896. - -; - -; 1990 a: Non-enzymic autoxidative reactions of caffeic acid in wine. Amer. J. Enol. Viticull. 41, 84-86. - -;- -; 1990 b: Caffeic acid autoxidation and the effects ofthiols. J. Agricult. Food Chem. 38, 1789-1796. Garcia-Viguera, C.; Bridle, P. ; Bakker, J.; 1994: The effect of pH on the formation of coloured compounds in model wine solutions contain-ing anthocyanins, catechin and acetaldehyde. Vitis 33, 37-40. PICINELLI , A.; BAKKER, J .; BRIDLE, P.; 1994: Model wine solutions: Effect of sulphur dioxide on colour and composition changes during aging. Vitis 33, 31-35. 

Model vine solutions: Caffeic acid is not an important factor in colour and composition changes during red wine aging

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Model vine solutions: Caffeic acid is not an important factor in colour and composition changes during red wine aging

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