Polyphenols in Hellenic Wines: Creating Composition Tables as a Tool for Epidemiological Studies

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1 Journal of Wine Research, 2003, Vol. 14, No. 2 3, pp Polyphenols in Hellenic Wines: Creating Composition Tables as a Tool for Epidemiological Studies DIMITRIS P. MAKRIS, STAMATINA KALLITHRAKA and PANAGIOTIS KEFALAS Original manuscript received, November 2003 Revised manuscript received, December 2003 ABSTRACT Polyphenolic substances are of profound significance to both the technological and nutritional value of grapes (Vitis vinifera sp.) and wines. The Hellenic vineyard embraces a large number of native V. vinifera species which have a peculiar polyphenolic composition, as illustrated by a number of recent research works. For this reason it was deemed necessary to gather the bibliographical data that have been published so far, in order to provide a complete insight into the polyphenolic composition of Hellenic wines, with a view to it being a first step towards the creation of a database which might be of assistance in epidemiological research. Emphasis has also been given to some data that revealed valuable information on variety-related patterns for major phenolics in wines made from single, autochthonous cultivars. Introduction Viticulture and wine making in Greece have been widely practised since antiquity. Continuous and intensive selection of grape varieties that favoured the production of the desired wine style led over the centuries to a plethora of native cultivars (Vitis vinifera sp.), which possess various distinct oenological characteristics, and lend Hellenic wines peculiar organoleptic properties. Because of their unique varietal (genetic) diversity, Hellenic grapes may vary largely in the composition of certain specific constituents, which define decisively the overall quality of wines. Therefore, the examination of both volatile and non-volatile composition of grapes and wines is an indispensable element in choosing those technological applications that enable the production of high-quality wines. One of the major parameters that is of both technological and nutritional significance is the polyphenolic composition (Figures 1 and 2). Although various classes of polyphe- Dimitris P. Makris, Department of Oenology and Beverage Technology, Technological Education Institute of Athens, Ag. Spyridona Str., 12210, Egaleo, Athens, Greece ( dimitris@maich.gr). Stamatina Kallithraka, Institute of Wine, National Agricultural Research Foundation, 1 S. Venizelou Str., 14123, Lycovrysi, Athens, Greece. Panagiotis Kefalas, Department of Food Quality Management, Mediterranean Agronomic Institute of Chania, PO Box 85, 73100, Chania, Greece. ISSN print/issn online/03/02/ DOI: / Institute of Masters of Wine

2 104 D. P. MAKRIS ET AL. Figure 1. Prominent classes of non-flavonoid polyphenols occurring in wine. nols have been thoroughly studied with respect to their impact on the quality of wines, only relatively recently have these components gained increasing interest as nutritional antioxidants. Further, claims that these phytochemicals may also be involved in biochemical processes that result in suppressed rates of degenerative diseases have initiated a great effort to substantiate the potential anti-atherogenic and anti-cancer activity of polyphenols. In recent years evidence has accumulated suggesting that wine may be one of the most prominent elements that contribute to the beneficial health effects of the reputed Mediterranean diet, yet the examinations required to provide sufficient data for valid epidemiological studies are still incomplete. This review summarises early and recent data and aims at providing an up-to-date insight into the polyphenolic profile of Hellenic wines, with a view to it being a first step towards the creation of a database which might be of assistance in epidemiological research. Polypenolic Composition of White Wines Flavonols Total flavonols in experimental wines from various regions of Greece had an average concentration of 61.4 mg l 1 catechin equivalents (CTE), (Kourakou-Dragona and Sotiropoulou, 1985) (Table 1). Wines made from Vilana and Vilana/Sylvaner/Sauvignon contained moderate levels of flavonols (50 65 mg l 1 CTE) but Roditis, as well as combined vinifications of Fileri/Roditis/Arintho/Ugni Blanc, Lagorthi/Robola/Debina and Athiri/Roditis/Asyrtiko, produced wines enriched in flavonols, with concentrations reaching mg l 1 CTE. A more recent study on total flavonol determination in a representative lot of appellation of origin wines (Psarra et al., 2002) demonstrated that

3 POLYPHENOLS IN HELLENIC WINES 105 Figure 2. Principal flavonoid polyphenolic compounds encountered in wines. wines from Paros and Santorini were particularly rich compared with all the other samples analysed, their content varying from 51.3 to mg l 1 CTE (Table 1). A more detailed examination of the same wines using high performance liquid chromatography (HPLC) (Makris et al., 2003) revealed that the sum of catechin and epicatechin averaged 38.4 mg l 1. The mean values of individual flavonols were 27.4 and 11.1 mg l 1, for catechin and epicatechin, respectively (Table 1). In another study on varietal wines (Kallithraka et al., 2001), the mean concentration of catechin, epicatechin and procyanidins B 1 and C 1 amounted to 14.8, 6.7, 73.7 and 7.4 mg l 1, respectively (Table 1). Wines made from Asyrtiko contained the largest total concentration ( mg l 1,asopposed to wines from Moschofilero ( mg l 1 ). High flavonol content ( mg l 1 ) was also found in wines from the island of Kefalonia made from Robola. Wines and mistelles made from Muscat Lefko, from the island of Samos, contained relatively low catechin and epicatechin concentrations, ranging from 0.4 to 6.2 mg l 1 (Karagiannis et al., 2000).

4 106 D. P. MAKRIS ET AL. Table 1. Flavanol content in Hellenic white wines Number of samples (n) Compounds a Average value b Range b Method Reference 11 Total flavonols Spectrophotometry Kourakou-Dragona and Sotiropoulou (1985) 9 CT, ECT HPLC Karagiannis et al. (2000) 12 CT, ECT, B1, C HPLC Kallithraka et al. (2001b) 26 Total flavonols Spectrophotometry Psarra et al. (2002) 26 CT, ECT HPLC Makris et al. (2003) Compound assignments: CT, catechin; ECT, epicatechin; B1 and C1, procyanidins B1 and C1. Concentration is expressed as mg l 1. a b

5 POLYPHENOLS IN HELLENIC WINES 107 Hydroxycinnamates A survey of 26 wines from the appellation of origin covering the entire Hellenic vineyard (Psarra et al., 2002) showed that total hydroxycinnamate concentration lies between 64.4 and mg l 1 chlorogenic acid equivalents (CGAE), with an average value of mg l 1 CGAE. The richest wines were those made from Asyrtiko and Monemvasia, originating from the islands of Santorini and Paros, respectively, whereas wines made from Roditis, from the region of Patras, were found to contain the lowest amounts. Analytical studies employing HPLC, however, demonstrated that total hydroxycinnamates might vary from 93.4 to mg l 1 (Makris et al., 2003) (Table 2). Caftaric acid (caffeoyl-tartaric acid) was the predominant conjugate, accounting for 47.9% of total hydroxycinnamates, followed by caffeic acid (13.8%), 2-S-glutathionylcaftaric acid (13.1%), coutaric acid (7.0%), caffeic acid ethyl ester (6.8%), fertaric acid (6.2%), coumaric acid (4.3%) and ferulic acid (0.9%). Wines made from Asyrtiko, from the island of Santorini, were once again shown to be the richest, their total mean concentration varying from to mg l 1. Wines from Robola (island of Kefalonia) and Mantinia (Peloponnese) were also rich in hydroxycinnamates. By contrast, wines made from Roditis (Patra, Peloponnese) were the poorest compared with all samples analysed, having an average content of mg l 1. Another study performed on dry and sweet wines and mistelles made from Muscat Lefko, from the island of Samos (Karagiannis et al., 2000), gave an average value for total hydroxycinnamates of 37.5 mg l 1. Mean concentrations for caftaric acid, coutaric acid, caffeic acid and coumaric acid were 18.7, 10.3, 3.7 and 4.8 mg l 1, respectively (Table 2). Caffeic acid determined in varietal wines varied from 11.5 to mg l 1, with a mean concentration of 60.6 mg l 1 (Kallithraka et al., 2001b). Benzoates The analytical study carried out on varietal wines (Kallithraka et al., 2001) showed gallic acid vanillic acid and syringic acid to have mean contents of 6.1, 11.7 and 0.6 mg l 1. However, a survey on appellation of origin wines (Makris et al., 2003) showed that gallic acid varied from 1.9 to 84.7 mg l 1, the average being 13.8 mg l 1. Stilbenes The analytical investigation on trans-resveratrol concentration that was performed on selected samples, including appellation of origin, regional and table wines from different vintages and regions (Dourtoglou et al., 1999), revealed that the mean content of this particular stilbene was mg l 1. The highest amount was detected in a wine made from Savvatiano/Athiri (0.142 mg l 1 ), and the lowest (0.026 mg l 1 )inawine made from Roditis, originating from the region of Patras. Polyphenolic Composition of Red Wines Hydroxycinnamates The determination of caffeic acid in 21 high-quality wines selected from various locations throughout Greece showed that its concentration varied from 0.0 to mg l 1, with an average of 71.2 mg l 1 (Kallithraka et al., 2001b). The highest concentrations were found in wines produced from Xinomavro and Negoska, originating from Goumenisa (Macedonia), but also in wines produced from Xinomavro/Stavroto/Krasato, from

6 108 D. P. MAKRIS ET AL. Table 2. Hydroxycinnamate content in Hellenic white wines Number of samples (n) Compounds a Average value b Range b Method Reference 9 Caftaric, coutaric, caffeic, coumaric acids HPLC Karagiannis et al. (2000) 26 Total hydroxycinnamates Spectrophotometry Psarra et al., (2002) 26 Caftaric, coutaric, fertaric, caffeic, coumaric, ferulic acids, GRP, caffeic acid ethyl ester HPLC Makris et al. (2003) Compound assignment: GRP, grape reaction product (2-S-glutathionylcaftaric acid). Concentration is expressed as mg l 1. a b

7 POLYPHENOLS IN HELLENIC WINES 109 Rapsani (Thessaly). A more detailed study of selected varietal wines (Arnous et al., 2001) indicated that caftaric acid is the prevalent hydroxycinnamate, its mean content being mg l 1 (range mg l 1 ), representing 67.9% of all the derivatives detected. The mean contents of another four derivatives, namely coutaric acid, caffeic acid, coumaric acid and 2-S-glutathionylcaftaric acid (grape reaction product), were 91.6 (18.3%), 17.1 (3.4%), 12.7 (2.5%) and 39.7 mg l 1 (7.9%), respectively. The fact that wines made from Xinomavro are rich in hydroxycinnamates was confirmed, as wines from Naousa (Macedonia) had the highest total average values, ranging from to mg l 1. Flavanols The analysis of catechin and epicatechin in varietal wines showed that these two monomeric flavanols have average contents of 83.3 and 62.6 mg l 1 (Arnous et al., 2001) (Table 3). A more detailed investigation of flavanols also provided some information regarding the levels of certain characteristic proanthocyanidins (Kallithraka et al., 2001b). For catechin and epicatechin the corresponding average levels were 65.8 and 40.8 mg l 1, while procyanidins B 1 and C 1 were found to occur at mean concentrations of 76.3 and 15.9 mg l 1, respectively (Table 3). The highest total contents were detected in wines made from Xinomavro (348.9 mg l 1 ), Xinomavro/Roditis (337.0 mg l 1 ), Xinomavro/Stavroto/Krasato (255.5 mg l 1 ) and Limnio (289.1 mg l 1 ), whereas relatively low levels were determined in wines from Monemvasia/Mandilaria (108.4 mg l 1 ) and Kotsifali/Mandilaria (119.5 mg l 1 ). Sakkiadi et al. (2001) reported mean values of 60.5 and 37.0 mg l 1 for catechin and epicatechin, respectively, in varietal wines (Table 3). The spectrophotometric determination of the total flavanol fraction following derivatisation with p-(dimethylamino)-cinnamaldehyde in regional wines (Arnous et al., 2002b), but regional and appellation of origin, high-quality wines (Arnous et al., 2002a), selected to cover the entire Hellenic vineyard, also revealed that total flavanols may vary from to mg l 1 CTE, with an average level of mg l 1. Anthocyanins The anthocyanin fraction in Hellenic wines is the most studied one, and several reports have been published on the colour characteristics and anthocyanin composition not only of wines, but also of certain Hellenic native cultivars (Bena-Tzourou and Tsoutsouras, 1992; Lanaridis and Bena-Tzourou, 1997; Kallithraka et al., 2004). Studies of varietal wines showed total anthocyanin content to vary from 33 to 606 mg l 1, the average being mg l 1 (Harvalia and Bena-Tzourou, 1982). Wines made from Romeiko (Crete) were particularly poor, whereas Vapsa from the island of Paros gave wines rich in anthocyanins (Table 4). More recently, a study of several regional, aged wines (Arnous et al., 2002b) reported values of anthocyanin concentration between 44.3 and mg l 1 (mean mg l 1 ) (Table 4). With respect to the analytical anthocyanin composition, a survey of 19 high-quality representative wines (Kallithraka et al., 2001b) showed that the sum of the major anthocyanin pigments, namely delphinidin (Dp), cyanidin (Cy), petunidin (Pt), paeonidin (Pn), malvidin (Mv) and malvidin acetate (MvAc) glucosides, varied from 42.5 to mg l 1 (average mg l 1 ). The order of abundance of individual anthocyanins was Mv MvAc Pn Pt Dp Cy. The analysis of 26 aged red wines, however, indicated that total anthocyanin content, including also malvidin coumarate (MvCoum), ranged from 0.0 to mg l 1 (Arnous et al., 2002b), with an average of 50.9 mg l 1 (Table 4). In this case the order of

8 110 D. P. MAKRIS ET AL. Table 3. Flavonol concentration in Hellenic red wines Number of samples (n) Compounds a Average Value b Range b Method Reference 10 CT, ECT HPLC Arnous et al. (2001) 21 CT, ECT, B1, C HPLC Kallithraka et al. (2001) 13 CT, ECT HPLC Sakkiadi et al. (2001) 15 Total flavanols Spectrophotometry Arnous et al. (2002a) 27 Total flavanols Spectrophotometry Arnous et al. (2002b) Compound assignments: CT, catechin; ECT, epicatechin; B1 and C1, procyanidins B1 and C1. Concentration is expressed as mg l 1. a b

9 POLYPHENOLS IN HELLENIC WINES 111 Table 4. Anthocyanin content in Hellenic red wines Number of samples (n) Compounds a Average value b Range b Method Reference 12 Total anthocyanins Spectrophotometry Harvalia and Bena-Tzourou (1982) 19 Cy, Dp, Pn, Pt, Mv, MvAc HPLC Kallithraka et al. (2001) 15 Total anthocyanins Spectrophotometry Arnous et al. (2002a) 27 Total anthocyanins Spectrophotometry Arnous et al. (2002b) 27 Cy, Dp, Pn, Pt, Mv, MvAc, MvCoum HPLC Arnous et al. (2002a) Cy, Dp, Pn, Pt, Mv, MvAc, MvCoum: glucosides of cyanidin, delphinidin, paeonidin, petunidin, malvidin, malvidin acetate and malvidin coumarate, respectively. Concentration is expressed as mg l 1. a b

10 112 D. P. MAKRIS ET AL. Table 5. Trans-resveratrol content in Hellenic red wines Number of samples (n) Average value a Range a Method Reference GC-MS b Goldberg et al. (1995) HPLC Dourtoglou et al. (1999) HPLC Kallithraka et al. (2001a) HPLC Sakkiadi et al. (2001) a Concentration is expressed as mg l 1. b Gas chromatography-mass spectrometry. abundance was Mv MvAc MvCoum Pt Dp Pn Cy. In both studies wines made from Agiorgitiko were particularly rich in anthocyanins, which also holds true for wines from Syrah and Merlot/Cabernet Sauvignon. Flavanols There are only two reports on flavonols in Hellenic red wines. Sakkiadi et al. (2001) reported quercetin and rutin to have average concentrations of 6.9 and 6.5 mg l 1, respectively, in varietal wines. The examination of aged varietal wines showed no occurrence of aglycones, but rutin and quercitrin were found to occur at mean levels of 18.1 and 43.9 mg l 1, respectively (Arnous et al., 2001). The highest contents were detected in wines made from Agiorgitiko and Syrah. Benzoates The analysis of several red wines (Kallithraka et al., 2001b) indicated that gallic acid is the prevalent benzoic acid derivative, with a mean concentration of mg l 1, followed by vanillic acid (25.8 mg l 1 ) and syringic acid (11.6 mg l 1 ). These results were confirmed by a study of varietal aged red wines (Arnous et al., 2001), which demonstrated that gallic acid is the most abundant benzoate (mean mg l 1 ), accompanied by lower amounts of other analogues, including syringic acid (38.3 mg l 1 ), p-hydroxybenzoic acid (7.2 mg l 1 ) and protocatechuic acid (4.4 mg l 1 ). Stilbenes A first examination of trans-resveratrol concentration in red Hellenic wines reported values ranging from 0.6 to 4.3 mg l 1 (mean 1.95 mg l 1 ) (Goldberg et al., 1995). An analytical survey conducted on 15 commercial wines showed that the content of this stilbenic metabolite varies from 0.33 to 1.57 mg l 1, with a mean of 0.87 mg l 1 (Dourtoglou et al., 1999). It was also indicated that wines made from Mandilaria and Monemvasia may be richer in trans-resveratrol (Table 5). This observation was confirmed by a subsequent investigation into trans-resveratrol in 29 red wines of appellation of origin (Kallithraka et al., 2001a), which also showed that the concentration lies between 0.55 and 2.53 mg l 1, the average being 1.11 mg l 1 (Table 5). The analysis of 13 varietal wines gave values from 0.38 to 2.14 mg l 1 (Sakkiadi et al., 2001) (Table 5) and a mean of 1.14 mg l 1,inaccordance with the previous studies. Varietal Potential and Variety-related Patterns The examination of the analytical polyphenolic composition has in some instances provided evidence for the potential of certain cultivars for polyphenol biosynthesis. It is

11 POLYPHENOLS IN HELLENIC WINES 113 irrefutable that the amounts, as well as the various species, of phenolics that occur in wines depend on a wide range of factors, including cultural practices, local climatic conditions, vinification techniques and storage and ageing conditions, but the results that have been drawn may be indicative of the polyphenolic richness for certain cultivars. The critical assessment of the data from the wines analysed clearly indicates some cultivars to be distinctive for their exceptional polyphenolic potential. Asyrtiko is a native V. vinifera variety, and is cultivated mainly on the island of Santorini. The wines produced are particularly rich in both flavanols and non-flavanoid phenolics, such as hydroxycinnamates (Makris et al., 2003), but the examination of seeds from this variety (Guendez et al., 2004) showed its exceptional capacity in producing flavonols, including catechin, epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate and the procyanidin dimmers B 1 and B 2. The results from seeds were also consistent for Athiri, which is cultivated on the island of Rhodes and gives wines enriched in polyphenols, and for Savvatiano, from the region of Patras, confirming its low potential. In relation to red varieties that were found to produce wines with high polyphenol levels, additional information has been obtained from the analysis of major anthocyanin pigments in berries (Kallithraka et al., 2004). Mandilaria, a variety widely planted on the island of Rhodes but also on other Aegean islands, was found to be significantly richer compared with several other native and international varieties, which also holds true for the flavonol content of seeds (Guendez et al., 2003). A very similar trend was seen for Vapsa, but results were not consistenty for Mavrodafni. These findings suggest that the investigation of the polyphenolic composition of various tissues of grapes may be crucial in assessing the potential of a given variety. The analytical composition data that have been available to date also permit the distinction of trends related to specific phenolic metabolites, and therefore recognise variety-dependent patterns. For white wines, it is evident that the Paros variety gives wines which are particularly enriched in flavonols and hydroxycinnamates, but also gallic acid. Wines made from Asyrtiko are compositionally very similar, but wines made from Robola are significantly poor in flavonols and gallic acid, as opposed to their hydroxycinnamate content, which is comparable to that of wines made from Paros and Asyrtiko. By contrast wines made from Roditis and Muscat of Alexandria are considerably poorer in both hydroxycinnamates and flavonols (Makris et al., 2003). In a similar fashion, red wines made from Agiorgitiko are rich in anthocyanins (Arnous et al., 2001, 2002a; Kallithraka et al., 2001a), but wines made from Xinomavro are rich in flavanols (Kallithraka et al., 2001a; Sakkiadi et al., 2001) in spite of their low anthocyanin content (Arnous et al., 2002a; Kallithraka et al., 2001a). Furthermore, Vapsa, Mandilaria and Mavrodafni give wines enriched in anthocyanins (Harvalia and Bena-Tzourou, 1982), consistent with their high anthocyanin capacity (Kallithraka et al., 2004). For trans-resveratrol, which is a minor constituent, no particular difference is seen in wines from Agiorgitiko and Xinomavro (Kallithraka et al., 2001a; Sakkiadi et al., 2001), but wines made from Mandilaria and Mandilaria/Monemvasia and Liatiko appear to contain more important amounts of this stilbenic metabolite. References ARNOUS, A., MAKRIS, D.P. and KEFALAS, P.(2001) Effect of principal polyphenolic components in relation to antioxidant characteristics of aged red wines, Journal of Agricultural and Food Chemistry, 49, ARNOUS, A., MAKRIS, D.P. and KEFALAS, P.(2002) Anthocyanin composition and colour characteristics of selected aged wines produced in Greece, Journal of Wine Research, 13,

12 114 D. P. MAKRIS ET AL. ARNOUS, A., MAKRIS, D.P. and KEFALAS, P. (2002b) Correlation of pigment and flavonol content with antioxidant properties in selected aged regional wines from Greece, Journal of Food Composition and Analysis, 15, BENA-TZOUROU, E. and TSOUTSOURAS, E. (1992) The colour of wines made from Xinomavro grapes (Vitis vinifera L.), Proceedings, 1st Hellenic Congress of Oenology, Athens, (in Greek). DOURTOGLOU, V.G., YANNOVITS, N.G., TYCHOPOULOS, V.G. and MAMVAKIAS, M.M. (1994) Effect of storage under CO 2 atmosphere on the volatile, amino acid, and pigment constituents in red grape (Vitis vinifera L. var. Agiorgitiko), Journal of Agricultural and Food Chemistry, 42, DOURTOGLOU, V.G., MAKRIS, D.P., BOIS-DOUNAS, F. and ZONAS, C. (1999) Trans-resveratrol concentration in wines produced in Greece, Journal of Food Composition and Analysis, 12, GOLDBERG, D.M., YAN, J., NG, E., DIAMANTIS, E.P., KARUMANCHIRI, A., SOLEAS, G. and WATER- HOUSE, A.L. (1995) A global survey of trans-resveratrol concentrations in commercial wines, American Journal of Enology and Viticulture, 46, GUENDEZ, R., KALLITHRAKA, S., MAKRIS, D.P. and KEFALAS, P. (2004) A survey on the analytical polyphenolic composition of seeds from grape varieties (Vitis vinifera sp.) cultivated in Greece: implications for the exploitation as a source of value-added phytochemicals, Phytochemical Analysis (in press). HARVALIA, A. and BENA-TZOUROU, I.(1982) Étude de quelques facteurs influençant la couleur des vins rouges Helleniques, Connaissance de la Vigne et du Vin, 16, KALLITHRAKA, S., ARVANITOYANNIS, I., EL-ZAJOULI, A. and KEFALAS, P.(2001a) The application of an improved method for trans-resveratrol to determine the origin of Greek red wines, Food Chemistry, 75, KALLITHRAKA, S., ARVANITOYANNIS, I., KEFALAS, P., EL-ZAJOULI, A., SOUFLEROS, E. and Psarra, E. (2001b) Instrumental and sensory analysis of Greek wines; implementation of principal component analysis (PCA) for classification according to geographical origin, Food Chemistry, 73, KALLITHRAKA, S., MOHDALY, A.A.-A., MAKRIS, D.P. and KEFALAS, P. (2004) Determination of major anthocyanin pigments in Hellenic native grape varieties (Vitis vinifera sp.): association with antiradical efficiency, Journal of Food Composition and Analysis (in press). KARAGIANNIS, S., ECONOMOU, A. and LANARIDIS, P. (2000) Phenolic and volatile composition of wines made from Vitis vinifera cv. Muscat Lefko grapes from the island of Samos, Journal of Agricultural and Food Chemistry, 48, KOURAKOU-DRAGONA, S. and SOTIROPOULOU, S.(1985) The qualitative potential of the Hellenic vineyard in white wine-grape varieties, Hellenica Oenologica Chronica, 4, (in Greek). LANARIDIS, P. and BENA-TZOUROU, E. (1997) Étude des variations des anthocyanes pendant la maturation des raisins de cinq cépage rouges, cultivé en Grèce, Journal International des Sciences de la Vigne et du Vin, 31, MAKRIS, D.P., PSARRA, E., KALLITHRAKA, S. and KEFALAS, P. (2003) The effect of polyphenolic composition as related to antioxidant capacity in white wines, Food Research International, 36, PSARRA, E., MAKRIS, D.P., KALLITHRAKA, S. and KEFALAS, P. (2002) Evaluation of the antiradical and reducing properties of selected Greek white wines: correlation with polyphenolic composition, Journal of the Science of Food and Agriculture, 82, SAKKIADI, A.-V., HAROUTOUNIAN, S.A. and STAVRAKAKIS, M.N. (2001) Direct HPLC assay of five biologically interesting phenolic antioxidants in varietal Greek red wines, Lebensmittel-Wissenschaft und-technologie, 34,