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González Hernández, G.; Hardisson de la Torre, A.; Arias León, J. J. Colour and total phenols content in traditionally made red wine from the Tacoronte-Acentejo D.O.C. area (Canary Islands) Ciencia y Tecnología Alimentaria, vol. 3, núm. 4, julio, 2002, pp. 217-222 Sociedad Mexicana de Nutrición y Tecnología de Alimentos Reynosa, México

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COLOUR AND TOTAL PHENOLS CONTENT IN TRADITIONALLY MADE RED WINE FROM THE TACORONTE-ACENTEJO D.O.C. AREA (CANARY ISLANDS)

COLOR Y CONTENIDO DE POLIFENOLES EN EL VINO TRADICIONAL EN RAMA DEL ÁREA DE DENOMINACIÓN DE ORIGEN TACORONTE-ACENTEJO (ISLAS CANARIAS)

COR E CONTIDO DE POLIFENOIS NO VIÑO TRADICIONAL EN RAMA DA ÁREA DE DENOMINACIÓN DE ORIXE TACORONTE-ACENTEJO (ILLAS CANARIAS)

González Hernández, G. 1*; Hardisson de la Torre, A.2; Arias León, J. J.1

1Department of Analytical Chemistry, Nutrition and Food Science, University of La Laguna, 38071 Santa Cruz de Tenerife, Spain. 2Department of Obstetrics and Gynaecology, Paediatrics, Preventive Medicine and Public Health, Toxicology and Medical Legislation, University of La Laguna, Spain.

*Author to whom correspondence should be addressed. Phone +34 922 318047, Fax +34 922 318003, E-mail: [email protected]

Recibido: 25 de Octubre, 2001; recibida versión revisada: 18 de Febrero, 2002; aceptado: 25 de Marzo, 2002 Received: 25 October 2001; revised version received: 18 February 2002; accepted: 25 March 2002 Abstract The present study determines wine colour and total polyphenol content in traditionally produced red wines (without final filtering and stabilisation) from the Tacoronte-Acentejo Designation of Origin Regulated area in Canary Islands (Spain). Different mathematical models were assayed in order to establish the linear relationship between certain physicochemical measurements. Therefore multiple correlation of colour against permanganate index, sulphur dioxide, and pH, and correlation of colour parameters with each other were studied. Thus, it can be used as a routine control for the qualification of the wine in order to know the ageing process. It was noticed that hue is the colour parameter best defined by the three variables examined. In regard to permanganate index, our results showed that 68% of must samples contain an equivalent amount of permanganate between 3.94 to 11.2 meq/L (milli- equivalents per litre), with mean content in wines of 33.3 meq/L. There is not difference in the permanganate index between young and aged wine. © 2002 Altaga. All rights reserved.

Key words: phenol, colour, must, wine.

Resumen Se estudia el color y el contenido de polifenoles en vinos en rama tradicionales procedentes de la Denominación de Origen Tacoronte-Acentejo de Canarias (España). Se aplican distintos modelos lineales para establecer la relación matemática que existe entre los parámetros que definen el color y el índice de permanganato, dióxido de azufre y pH; además de las correlaciones de los parámetros del color entre sí. Los resultados pueden ser utilizados como análisis de control rutinario para calificar el vino como joven o viejo, y conocer la evolución del envejecimiento. Se pudo observar que es la tonalidad del color el parámetro que mejor queda definido por las tres variables examinadas. Con respecto al índice de permanganato, el 68% de las muestras de mosto presentan una cantidad que oscila entre 3,94 y 11,2 meq/L (miliequivalentes por litro), con un contenido medio en los vinos de 33,3 meq/L, sin que exista diferencia entre vinos jóvenes y envejecidos. © 2002 Altaga. Todos los derechos reservados.

Palabras clave: Fenol, color, mosto, vino.

Resumo Estudiouse o cor e o contido en polifenois nos viños en rama tradicionais procedentes da Denominación de Orixe Tacoronte- Acentejo de Canarias (España). Aplicáronse distintos modelos lineais para establecer a relación matemática que existe entre os parámetros que definen o cor e o índice de permanganato, dióxido de xofre e pH; ademais das correlacións dos parámetros do cor entre si. Os resultados poden ser utilizados como análise de control rutineiro para cualificar o viño como xoven ou vello, e coñecer a evolución do envellecemento. Púidose observar que é a tonalidade da cor o parámetro que mellor queda definido polas tres variables examinadas. Con respecto o índice de permanganato, o 68% das mostras de mosto presentan unha cantidade que varia entre 3,94 e 11,2 meq/L (miliequivalentes por litro), con un contido medio nos viños de 33,3 meq/L, sen que exista diferencia entre viños xóvenes e envellecidos. © 2002 Altaga. Tódolos dereitos reservados.

INTRODUCTION In food and beverages in general, particularly in wine, colour is an essential physical property in quality Viticulture in the Canary Islands has three main evaluation. Objective methods of determination for features that distinguish it from that of the rest of the world. chromatic evaluation are necessary (Carrubba et al., 1985; For one, Phylloxera is not present in this area, which means Heredia et al., 1986). Phenol components, specifically that the plant reproduces directly from the vine shoot, anthocyans, are the main cause of the typical violates red which is physiologically advantageous and allows the colour of red grapes, as well as of juices and wines conservation of a large number of indigenous varieties in obtained from them. Anthocyans act as true acid-base their purest form (López Arias et al., 1993). Also, the indicators and their colour changes in the presence of soil is of volcanic origin and is exceptionally rich in sulphur dioxide and metals (Primo Yúfera, 1979). The minerals. Moreover, temperatures are very mild (20ºC a red colour is a result of the amount of anthocyans, directly, 25ºC) because of the influence of alisios winds, i.e. the or by interaction with proteins, polysaccharides or other prevailing NE trade winds, and the Canary Islands’ phenols (Robichaud & Noble, 1990). oceanic current. Both phenomena modify temperatures The phenols content of wine depends on the grape throughout the year, making them milder than would be variety, growing site, cultivation system, climate, soil type, expected at this latitude (Marzol, 1990 & 2000; Rodríguez harvesting time, production process and ageing, Rodríguez, 1973). fundamentally (Brossaud et al., 1999; Mayén et al., 1995; Traditionally made wines in the Canary Islands, Shahidi & Naczk, 1995). Nowadays, researchers which do not involve filtering and stabilisation comprise determine usually the individual compounds (Malovaná an important fraction of the total production in this region et al., 2001; Pazourek et al., 2000; Rodríguez-Delgado et (86%) (López Arias et al., 1993). Since little is known al., 2000). In this work total phenols content is studied, about the total phenols content and colour of this type of because of the whole family of this compounds, more than wine, a study was conducted on some of the most individual ones, are responsible of the sensorial representative wines. The area chosen was the Tacoronte- characteristics above mentioned. The total phenol content Acentejo area, whose wines have been long deservedly reported in the literature, expressed in oxidizable matter renowned and popular. This is the most important area of (O.M.), is 20 meq/L to 40 meq/L in young red wine and the archipelago in terms of volume of production and it is up 50 meq/L in aged one. The amount is higher in also one of the oldest of the wine-growing regions. With winemaking with stems and increase parallel to ageing a total of 2,422 hectares planted Tacoronte-Acentejo is (Ribereau-Gayon & Peynaud, 1962). In the Canary region, the Canaries’ largest and densest wine-growing area. The fermentation takes place with all stems present, or with annual total wine output in the Canaries stands at 25.3 partial de-stemming. Nevertheless, Amerine and Ough million litres, of which a mere 3.5 million litres are (1976) suggested that those values were slightly high produced using state-of-the-art technologies (López Arias already at that time, and indicated that trends were the et al., 1993). The remaining 21.8 million litres are elaboration of wines smoother. Nowadays that is proved. produced and sold in bulk in the myriad of small traditional Seventy-five red wines from Tenerife were studied wine-producing sites or wineries scattered throughout the to know the evolution of total content of phenols and various wine-growing regions (González, 1998). The colour in regarding to ageing. On the other hand, this paper geographical area studied lies on the coast on the northern is continuing of the physical-chemical analysis of the side of Tenerife from 200 to 600-m above sea level. studied wines. Sulphur dioxide (SO2) and pH were Phenols influence the sensorial characteristics of determined using the reference methods of the European wine (palatability, astringency and hardness); hygiene Community (EEC, 1990) (González Hernández, 1994; problems (vitamin P effect and bactericidal action) and González et al., 1999). the transformations undergone by wine (treatments and ageing). Moreover, since they originate in the solid parts of the cluster, skin and seeds, they account for all the MATERIAL AND METHODS differences between white and red wines (Ribereau-Gayon et al., 1980). Samples Recently, there is a considerable interest in the food The present study was undertaken with samples of industry and in preventive medicine in the development artisan red wine from the Tacoronte-Acentejo of “natural antioxidants” from plant material (Kanner et Denomination Area of Tenerife. The musts used to make al., 1994) such as flavonoids (Rodríguez Lión et al., 1998; red wine come from a mixture of red and white Vitis Vinson & Hontz, 1995). Their effects as captors of free vinifera grape varieties, mixed in a ratio of 85% to 15%, radicals (Kovac et al., 1992), their influence on respectively. The red grape varieties used were listán negro arteriosclerosis, and their anti-inflammatory and (60%), negramoll (20%), other indigenous varieties (5%), antiallergenic properties (Escribano-Bailón et al., 1992; and the listán blanco white variety (15%). This is the Kovac et al., 1992) have been recognised. Due to their approximate composition of the traditionally musts of this action on free radicals, the potential anticarcinogenic region (López Arias et al., 1993). properties of flavonoids are being studied (Hertog et al., Once the grapes have been pressed, they then 1993). The bulk of these compounds in the diet, at least undergo a process of mashing-fermentation in large, in Mediterranean countries, come from grapes and wine shallow vats. The prolonged aeration of the musts (Escribano-Bailón et al., 1992). accelerates the start of the fermentation process through 218 ALTAGA ©2002 González Hernández et al.: Colour and total phenols content in traditionally made red wine ... the rapid growth of the yeast. After 48 – 72 h, the solid Table 1.- Descriptive statistics of levels of permanganate index (meq/L material is pressed and the liquid is passed into chestnut O.M.) of red wine from the Tacoronte-Acentejo area of Tenerife. a Seven samples of must were missed out. tree barrels with a capacity of 400-600 L, where fermentation finishes. The wine is then kept in these same Must Young Aged All barrels to acquire its typical “cru”. One of the main features wine wine wines of this kind of wine is its high alcohol content (González N 33a 40 35 75 Hernández et al., 1997). Mean value 7.58 33.3 33.3 33.3 Forty samples of must from 40 representative S.D. 3.64 9.67 11.4 10.5 wineries in the area were collected during the harvesting Minimum 0.65 17.3 16.0 16.0 time. Afterwards 40 samples of young red wine coming Maximum 15.9 61.7 74.5 74.5 from these musts were collected in January, February, V.C. % 48.0 29.1 34.4 31.4 March and April, and 35 samples of the same wines were collected in June and July, after an average of 106-days Statistical analysis ageing (five samples missing). In order to preserve stability The software package Statgraphics Plus 4.0 (INST, during manipulation, toluene was added to the samples. CA) was used for the statistical analysis. Linear and non- linear mathematical models were assayed to establish the Analytical Methods relationship between certain physicochemical The amount of phenol substances (Permanganate measurements. Index, IMn) was determined through evaluation with

KMnO4 according to the following procedure (Ribereau- Gayon et al., 1980): 50 ml of 0.015% indigo carmine in RESULTS AND DISCUSSION 0.60 N sulphuric acid and 2 ml of wine or 1 ml must were placed in a measuring glass. The solution was then Table 1 gives a statistical description of IMn for the evaluated with KMnO 10-2 N. The same evaluation 4 samples of musts and red wines studied. In musts, contents procedure was employed with 50 ml of the same sulphuric range between 0.650 and 15.9 meq/L. This wide range is solution of indigo carmine, to which was added 2 ml of a thought to be due to the different environmental conditions tartaric solution of 5 g/l, partially neutralised and with of each winery, i.e., most samples present a detectable 10% alcohol. The difference in MnO - volume is the 4 amount of matters which are susceptible of cold amount expended by the phenol compounds. The analysis permanganate oxidation, notwithstanding the fact that they ran for duplicate. were collected immediately after grape crushing. Even Absorbance and transmittance measurements were though a mere 5% of total phenols come from the juice taken using Perkin-Elmer 5505 and Perkin-Elmer Hitachi (Alonso et al., 1986). Content can be explained by a rapid 200 spectrophotometers, equipped with quartz cells of 0.1, dissolution from solid parts due to the rather slow crushing 0.2, 0.5 and 1 cm thickness, which were adequate to make process, which leads to a period of intense contact between dilution unnecessary. Absorbances were measured at 420, the juice and solid parts before sample collection (Alonso 520 and 620 nm; colouring intensity I and hue N are given et al., 1986; Otero et al., 1986). 60% of must samples are by the expressions (EEC, 1990): observed to have values ranging between 4 and 11 meq/L O.M. I = A + A + A 420 520 620 It should be noted that in approximately 40% of N = A / A 420 520 the samples studied sulphur dioxide had been added, a compound that has a synergy effect with o- In order to obtain more precise information for a dihydroxyphenols (Cela et al., 1982; Peris-Tortajada et better definition of the colour of red wines of the studied al., 1989). zone, we used “three-stimuli”, or three-stimulate co- In the case of wines total phenol content was found ordinates X,Y,Z based on the system of the C.I.E. to be on average 33.3 meq/L O.M., ranging from 16.0 to (Commission Internationale de l’Eclairage). x,y- 74.5 meq/L. The results indicate a homogeneous chromaticity co-ordinates of the representative point of distribution, with a variation coefficient of 31.4%. The wine on the C.I.E. three-chromatic diagram, as well as figures for the studied wines in general are deduced to be the relative luminance RL, were calculated from the rather low and they are classified as light wines by following expressions (OIV, 1990): Ribereau-Gayon et al. (1980). One must also bear in mind the evolution of consumers’ taste towards milder wines X = 0.42 ´ T + 0.35 ´ T + 0.21 ´ T 625 550 445 (Muñoz Alcón & Mariné Font, 1978) and, consequently, Y = 0.20 ´ T + 0.63 ´ T + 0.17 ´ T 625 550 495 the evolution of winemaking techniques towards shorter Z = 0.24 ´ T + 0.94 ´ T 495 445 maceration periods. In any case, these values roughly x = X/X+Y+Z coincide with those reported in the literature for Spanish y = Y/X+Y+Z wines from different parts (Gil & Gómez-Cordovés, 1985; RL = Y expressed as a percentage Muñoz Alcón & Mariné Font, 1978). In accordance with Rodríguez et al. (1987) the Where T is transmittance at the indicated wines studied by us fall into the category of common sweet wavelengths. wines, with contents slightly below the average of 40.4 meq/L indicated by Amerine and Ough (1976). 219 Cienc. Tecnol. Aliment. Vol. 3, No 4, pp. 217-222, 2002 ISSN 1135-8122 ©2002 ALTAGA

In regard to the colour, Table 2 shows the results excessive air contact, leading to considerable oxidation of colour defining parameters for the 75 samples of red and, consequently, dark reddish hues improper of young wine studied. Analysis of results and comparison of young wines are obtained. and aged wines show a decrease of 0.035 units in x- In any case, the results obtained by us are of the chromatic value, whereas the y value remains virtually same order of magnitude as those reported by Gil and the same. Gómez-Cordovés (1985) for hue and by Heredia Mira Figure 1 shows the representation of chromaticity and Guzmán Chozas (1990) for colouring intensity and values on the CIE three-chromatic diagram (Lozano, luminance. However, other authors (Carrubba et al., 1985; 1979). It can be seen that the young wines are seen to Navarro et al., 1988) obtain significantly different levels have a number of colour points close to the most saturated for the monastrell and tempranillo varieties, probably due red zone, i.e., with a purest hue. Other points lie in the to the fact that colouring depends largely on grape variety. pure reddish orange zone, shifting to the clearer red zone In order to confirm that there were indeed two due to ageing and, lastly, are situated in the orange-pink groups of samples, young and aged wines, the statistical zone. Numerically, this means that wine ageing involves significance of the results obtained was analysed. Table 2 a decrease in colour intensity, with lower x-chromaticity shows that the difference was 99 % significant (a < 0.01) values. The presence of a group of samples with an x- for colouring intensity, 98% (a < 0.02) for x-chromaticity chromaticity value of below 0.5 and which are closer to being colourless than to the characteristic red colour of red wine can also be detected. This is probably due to the 0.4 ORANGE ILLUMINATING heavy addition of SO2 in these samples (González et al., 1999). ORANGE PINK REDISH ORANGE Luminance values (Y %) increase with ageing. In y - the examined samples, 3-month ageing in wood barrels chromaticity leads to as much as a 3.40 unit’s average increase. Colour 0.3 intensity (I) for the wines from these vine ranges from PINK 1.56 to 9.89, with a mean value of 4.01; ageing causes a RED decrease of approximately one unit. In regard to hue (N) PURPLISH PURPLISH RED a tendency towards an increase can be observed. In the PINK RED three months of ageing, the value increases from 0.873 to PURPLE 0.938 (for young and aged wines, respectively). 0.2 The most salient aspect is the high value of N 0.4 0.5 0.6 0.7 (Table 2), in spite of the fact that they are young wines, x-chromaticity usually drank within one year following production and, in most cases, within 6 months, when the mean hue value Figure 1. Section of the CIE (International Clarification (young wine) is already 0.873. In our opinion, such high Commission) chromatic diagram showing the approximate areas values are due to the widespread use of wooden barrels corresponding to each specific colour area (according to Lozano, with a capacity for approximately 600 L. These permit 1979); 5young,

Table 2.-Descriptive statistics of the results obtained for chromaticity, colour intensity, hue and luminance, distributed according to young and aged wines, as well as statistics for total results. * a values of significance tests of the differences between groups when colour parameter means are compared.

Young wine Aged wine All Young wine Aged wine All N 40 35 75 40 35 75 x-chromaticity y-chromaticity (0.0120)* (0.1021) Mean val. 0.596 0.561 0.580 0.318 0.323 0.321 Minimum 0.462 0.437 0.437 0.299 0.305 0.299 Maximum 0.676 0.649 0.676 0.348 0.360 0.360 V.C. % 9.91 10.9 10.7 3.67 4.13 3.94 Colour intensity Hue (0.0044) (0.0271) Mean val. 4.48 3.46 4.01 0.873 0.938 0.904 Minimum 2.08 1.56 1.56 0.685 0.770 0.685 Maximum 9.89 5.98 9.89 1.19 1.27 1.27 V.C. % 39.8 30.8 39.1 14.8 12.7 14.2 Relative luminance (0.0263) Mean val. 8.08 11.5 9.67 Minimum 0.541 1.94 0.541 Maximum 23.9 31.3 31.3 V.C. % 67.9 64.9 68.9

220 ALTAGA ©2002 González Hernández et al.: Colour and total phenols content in traditionally made red wine ... value and 97% for hue and luminance. It was non- Table 4.- Confidence intervals at 95% and significance level for the significant (a > 0.1) for the y-chromaticity value. aforementioned linear relationship of red wine colour from the Tacoronte- A study was undertaken of the correlation in order Acentejo area of Tenerife. a,b,c,d = Respective coefficients of the corresponding equation. D = Confidence interval (95%). a = to establish the linear relationship between certain Significance level. physicochemical measurements, which influence in the colour of the wine. So multiple correlation of a b c d permanganate index, sulphur dioxide and pH with the D ±0.6921 ±0.00304 ±0.00031 ±0.1946 colour was studied. In Table 3 can be seen that a 0.0591 0.0000 0.0002 0.0000 chromaticity (x,y) and colour intensity (I) are the parameters which achieve the best regression coefficient when colour is correlated with IMn and SO2. However, assayed to establish relationship of the colour parameters when the influence of pH is also studied, hue (N) is the with each other. The correlation coefficients are better colour parameter best defined by the three variables than those for the linear combination are. examined. The corresponding equation is as follows (U = In conclusion, the permanganate index obtained is a + bX + cY + dZ): comparable to that of wines from other regions. With regard to colour, ageing for approximately 100 days leads

N = -0.6649 - 0.00858 ´ IMn + 0.00064 ´ [SO2]+ to an increase in the average level of luminance and hue, 0.5029 ´ pH whereas x-chromaticity and colour intensity both decrease. Hence, the marked evolution towards ageing clearly points Figure 2 shows the graphic representation and to the need to consume this type of wines within the first Table 4 gives the confidence intervals and the significance year. levels for the respective coefficients of this linear regression. Also, several non-linear mathematical models were REFERENCES

Alonso, E.; Estrella, M. I.; Revilla, E. 1986. Los compuestos 1.3 polifenólicos en elaboración y envejecimiento del vino. 1.2 Alimentación Equipos y Tecnología 5, 163-168. Amerine, M. A.; Ough, C. S. 1976. Análisis de vinos y mostos, 1.1 pp 89-99. Acribia, Zaragoza, Spain.

1 Brossaud, F.; Cheynier, V.; Asselin, C.; Moutounet, M. 1999. Flavonoid compositional differences of grapes among 0.9 site test plantings of Cabernet franc. American journal Observed of enology and viticulture 50, 277-284. 0.8 Carrubba, E.; Torina, G.; Alagna, C. 1985. Indagine analitica 0.7 su vini siciliani monovarietali; caracterittiche cromatiche di vini rossi. Vignevini 6, 27-34. 0.7 0.8 0.9 1 1.1 1.2 1.3 Cela, R.; Natera, R.; Pérez-Bustamante, J. A. 1982. Predicted values Determinación de índices de polifenoles totales en mostos y vinos blancos. Anales de bromatología Figure 2. Regression between predicted and observed values when hue is correlated against IMn (meq/L), total SO level (mg/L) and pH, c.c. = XXXIV, 207-217. 2 EEC. 1990. Regulation 2676/90, 17 September, establishing 0.818 (SO2 content from González et al., 1999, and pH from González Hernández, 1994). the Community Analysis Methods to apply in the Wine

Table 3.- Multiple regression analysis of parameters related with red wine colour from the Tacoronte-Acentejo

area of Tenerife. SO2 content data from González et al., 1999, and pH data from González Hernández, 1994.

Dependent Independent variables U = a+bX+cY+dZ variable U c.c. X meq/L Y mg/L Z x-chrom. 0.747 y-chrom. 0.693 I IMn Total SO2 ¾¾ 0.735 N 0.640 Y% 0.672 x-chrom. 0.741 y-chrom. 0.725 I IMn Total SO2 pH 0.727 N 0.818 Y% 0.660

Sector, pp 122-131, and p 168. Official Diary of Mayén, M.; Mérida, J.; Medina, M. 1995. Flavanoid and non- European Communities, Brussels. flavanoid compounds during fermentation and post- Escribano-Bailón, T.; Gutiérrez-Fernández, Y.; Rivas-Gonzalo, fermentation standing of musts from cabernet sauvignon J. C.; Santos-buelga, C. 1992. Characterization of and tempranillo grapes. American journal of enology procyanidins of Vitis vinifera variety tinta del pais grape and viticulture 46, 255-261. seeds. Journal of agriculture and food chemistry 40, Muñoz Alcón, M. H.; Mariné Font, A. 1978. Determinación de 1794-1799. polifenoles en vinos. Anales de bromatología XXX, Gil, C.; Gómez-Cordovés, C. 1985. El contenido en polifenoles 107-122. totales, catequinas, o-difenoles y el color, de vinos, Navarro, G.; Zuñel, C.; Méndez, C.; Navarro, S. 1988. como característica varietal. Anales de bromatología Vinificaciones comparadas, en tinto tradicional y por XXXVII, 153-159. maceración carbónica, de Vitis vinifera variedad González, G. 1998. Estado actual de la vitivinicultura canaria. monastrell. II. Evolución del color. Anales de Algunos aspectos higiénico-sanitarios. Higia 14, 11- bromatología XL, l75-l80. 14. Office International de la Vigne et du Vin, O.I.V. 1990. Recueil González, G.; Hardisson de la Torre, A.; Arias León, J. J. 1999. des méthodes internationales d’analyse des vins et des Sulfur dioxide in traditionally-made red wine of the moûts, pp 29-39. Édition officielle. Property publishing, Tacoronte-Acentejo D.O.C. region, Canary Islands. Paris. Journal of Food Quality 22, 41-49. Otero, J. C.; Barroso, C. G.; López, L.; Cela, R.; Pérez- González Hernández, G. 1994. Caracterización fisicoquímica Bustamante, J. A. 1986. Estudio del índice de y sensorial de los mostos y vinos tintos de la parte polifenoles totales en el pardeamiento del vino fino de oriental de la denominación de origen Tacoronte- Jerez. Proceedings of the 8th Meeting on Viticulture Acentejo de Tenerife. Ph.D. Thesis, University of La and Oenology of Tierra de Barros, Badajoz, 123-130. Laguna, Spain. Pazourek, J.; González, G.; Revilla, A. L.; Havel, J. 2000. González Hernández, G.; Hardisson de la Torre, A.; Arias León, Separation of polyphenols in Canary Islands wine by J. J. 1997. Densidad, grado alcohólico y azúcares capillary zone electrophoresis without preconcentration. reductores del mosto y vino tinto tradicional de la Journal of Chromatography A 874, 111-119. comarca de denominación de origen Tacoronte-Acentejo Peris-Tortajada, M.; Pérez Cerrada, M.; Maquieira, A. 1989. (Islas Canarias). Alimentaria 284, 97-105. Automated determination of total polyphenols by means Heredia, F. J.; Camean, A. M.; Guzmán, M. 1986. Utilidad de of the Folin-Ciocalteu reagent. Química analítica. 8, los parámetros cromáticos en la evaluación de la calidad 211-222. de los vinos tintos. Revista de agroquímica y tecnología Primo Yúfera, E. 1979. Química agrícola. Vol. III: Alimentos, de alimentos 26, 477-481. 1st Issue, pp 315-334. Alhambra, Madrid. Heredia Mira, F. J.; Guzmán Chozas, M. 1990. Parámetros Ribereau-Gayon, J.; Peynaud, E. 1962. Análisis de vinos, pp cromáticos en vinos tintos españoles. Anales de 323-339. Aguilar, Madrid. bromatología XLII, 279-286. Ribereau-Gayon, J.; Peynaud, E.; Sudraud, P.; Ribereau-Gayon, Hertog, M. G. L.; Hollman, P. C. H.; Van de Putte, B. 1993. P. 1980. Ciencias y técnicas del vino. Vol. I: Análisis y Content of potentially anticarcinogenic flovonoids of control de los vinos, pp 441-479. Hemisferio Sur, tea infusions, wines, and fruit juices. Journal of Buenos Aires. agriculture and food chemistry 41, 1242-1246. Robichaud, J. L.; Noble, A. C. 1990. Astringency and bitterness Kanner, J.; Frankel, E.; Granit, R.; German, B.; Kinsella, J. E. of selected phenolics in wine. Journal of the science of 1994. Natural antioxidants in grapes and wines. Journal food and agriculture 53, 343-353. of agriculture and food chemistry 42, 64-69. Rodríguez, S.; Gímenez Plaza, J.; Cano Pavón, J. M. 1987. Kovac, V.; Alonso, E.; Bourzeix, M.; Revilla, E. 1992. Effect Evaluación del contenido de compuestos polifenólicos of several enological practices on the content of en vinos de Málaga. Alimentaria 183, 113-116. catechins and proanthocyanidins of red wines. Journal Rodríguez-Delgado, M. A.; Pérez, M. L.; Corbella, R.; of agriculture and food chemistry 40, 1953-1957. González, G.; García Montelongo, F. J. 2000. López Arias, M.; Armas Benítez, R.; Criado Ortega, M. 1993. Optimization of the separation of phenolic compounds Vinos de Canarias, pp 17-28. Official ed. of the by micellar electrokinetic capillary chromatography. Agriculture and Fishing Council of the Canary Islands Journal of Chromatography A 871, 427-438. Government, Santa Cruz de Tenerife, Spain. Rodríguez Lión, M. L.; Fernández del Pozo de Salamanca, M. Lozano, R. D. 1979. Diferencias de color. Investigación y B.; Zaragoza García, F. 1998. Principios activos de Ciencia. 39, 8-14. origen natural: flavonoides. Industria Farmacéutica 5, Malovaná, S.; García Montelongo, F. J.; Pérez, J. P.; Rodríguez- 87-92. Delgado, M. A. 2001. Optimisation of sample Rodríguez Rodríguez, J. 1973. La vid y los vinos de Canarias, preparation for the determination of trans-resveratrol p 39. Goya Artes Gráficas printing, Santa Cruz de and other polyphenolic compounds in wines by high Tenerife, Spain. performance liquid chromatography. Analytica chimica Shahidi, F.; Naczk, M. 1995. Phenolic compounds of beverages. acta 428, 245-253. In: Food phenolics: Sources, chemistry, effects, Marzol, M. V. 1990. Los factores atmosféricos y geográficos applications, pp 136-148. Technomic Publishing Co., que definen el clima del archipiélago canario. In: Pennsylvania. Climatología y medio ambiente, pp 151-176. University Vinson, J.A.; Hontz, B.A. 1995. Phenol antioxidant index: of Barcelona, Barcelona, Spain. comparative antioxidant effectiveness of red and white Marzol, M. V. 2000. El clima. In: Gran atlas de Canarias, pp wines. Journal of agriculture and food chemistry 43, 87-106. Editorial Interinsular Canaria, Canary Islands, 401-403. Spain.

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