Phenolic compounds and antioxidant activity of Macedonian red wines

The quantitative composition of phenolic compounds and antioxidant activity of Vranec, Merlot and Cabernet Sauvignon wines produced in 2006, 2007 and 2008 were determined and compared. The phenolic profile was established using high-performance liquid chromatography coupled with diode array detector and on line mass spectrometry (HPLC-DAD–ESI-MS and MS/MS) technique. A total of 65 phenolic compounds were determined in the wines including 14 anthocyanins, 18 pyranoanthocyanins, 16 flavonols, 8 hydroxycinnamic acids and their derivatives, 4 stilbenes, gallic acid and 4 flavan-3-ols. Hydroxyphenyl-pyranoanthocyanin content is reported for the first time in Macedonian red wines, ranging between 1.09 and 10.4 mg/L. 10-Carboxy-pyranomalvidin-3-glucoside and 10-p-hydroxyphenyl-pyranomalvidin-3-glucoside were the main compounds from vitisin-like and hydroxyphenyl-like pyranoanthocyanins, respectively. Vranec wines produced in 2008 presented highest concentration of anthocyanins (508 mg/L), vitisins (53.1 mg/L), hydroxyphenyl-pyranoanthocyanins (7.35 mg/L), flavonols (120 mg/L), hydroxycinnamic acid derivatives (352 mg/L), flavan-3-ols (98.9 mg/L), stilbenes (43.9 mg/L) and antioxidant activity (12.5 mM/L TE). Cabernet Sauvignon and Merlot had highest flavonols (152 and 119 mg/L) and flavan-3-ols concentration (150 and 111 mg/L) in 2006 and 2007, respectively, indicating the important role of variety, climate, storage conditions and winemaking techniques in wine phenolic composition. Factor analysis showed classification of wines according to the variety and content of the phenolic families and color characteristics

HPLC-MS and Spectrophotometric Assay of the Phenolic Content of Macedonian Red and White Grape Varieties

Grape polyphenols are characterized by a large range of structures diversely distributed in every part of the berry. The knowledge of the phenolic composition of grapes and its evolution during ripening is thus of crucial importance in relation to food quality. Among the phenolic compounds, the anthocyanins are responsible for the red color of the grapes, which are located in the skins, while flavanols and catechins intervene in their taste (astringency) and bitterness. In this study, the contents of total phenolics, total flavan-3-ols and total anthocyanins were determined in the pulp, skins and seeds of two red, Vranec and Merlot, and two white grape varieties, Smederevka and Chardonnay applying standardized spectrophotometric methods. Extraction of phenolic compounds was performed with acetone/water (80/20, v/v). The obtained results showed that the concentration of total phenols and flavan-3-ols was highest in the skins and seeds of Vranec grapes, while the pulp contained low amounts of these compounds. Chardonnay seeds contained higher amounts of phenolics and flavan-3-ols compared to Smederevka grapes. HPLC-MS analysis was performed in order to identify the phenolic components present in the grape, applying mobile phase consisting of 1 % (v/v) acetic acid in water (solvent A) and 1 % (v/v) acetic acid in methanol (solvent B). The presence of 15 anthocyanins (monoglucosides, acetylgucosides and coumaroylglucosides), 7 flavonols, 5 phenolic acids and derivatives and 3 flavan-3-ols was confirmed in the skins of red grapes

MALDI-TOF and HPLC-DAD-ESI/MS identification of phenolic compounds in Macedonian wines and grapes

Phenolic compounds are one of the major quality parameters in the grape and thus in the resulting wine. They contribute to sensory characteristics of wines, particularly color and astringency, and possess a wide range of biochemical and pharmaceutical effects, including antioxidant, antimutagenic, antimicrobial and anticarcinogenic effects. These constituents can be divided into two groups: non-flavonoids (hydroxybenzoic and hydroxycinnamic acids and stilbens) and flavonoids (anthocyanins, favonols and flavan-3-ols). MALDI-TOF and HPLC-DAD-ESI/MS methods were developed for simultaneous identification of phenolic acids, flavonols, anthocyanins, flavan-3-ols and stilbenes in Macedonian wines and grapes. A rapid MALDI-TOF method was developed for wine and grape fingerprinting without preparation of the samples for identification of anthocyanins introducing a new matrix, fullerene C70. Different MALDI matrices were tested: -cyano-4-hydroxycinnamic acid (CHCA); 2,5-dihydroxy benzoic acid (2,5-DHB); sinapic acid (SA); fullerene (C70) and measurements of some samples without matrix were done. It was found that fullerene can be used for identification of anthocyanins in wines and grapes and the sandwich method with this matrix was applied for all sample measurements. A simple HPLC-MS method was applied for simultaneous identification of phenolic compounds present in wine and grape samples. Analyses were performed on a C18 column with gradient elution using a binary mobile phase consisting of 1 % acetic acid in water and 1 % acetic acid in methanol. Identification of the components was based on retention times, UV-Vis and mass spectra by comparison with a few commercial standards. The optimized HPLC method was used for phenolics analysis in grapes and wines from Vranec, Merlot, Chardonnay and Smederevka varieties (harvest 2007). The obtained results confirm the great utility of ESI-MS coupled with HPLC for simultaneous analysis of non-flavonoid and flavonoid compounds in wine and grape samples, since coelution is not a problem in so far as they have different molecular masses

Phenolic Composition, Colour and Antioxidant Activity of Vranec, Merlot and Cabernet Sauvignon Wines from R. Macedonia

Wine quality largely depends on the phenolic compounds, which contribute to the wine colour, bitterness and astringency. Furthermore, phenolic compounds demonstrate the antioxidant potential of wines, which is mainly due to the flavonoids. In this study, phenolic composition, colour and antioxidant activity of Vitis Vinifera red wines Vranec, Merlot and Cabernet Sauvignon from three vintages, 2006, 2007 and 2008, produced in the Republic of Macedonia, have been evaluated. Separation of the individual antioxidant compounds, including monomeric anthocyanins, pyranoanthocyanins, flavonols, hydroxycinnamic acid derivatives and stilbenes has been performed using HPLC-DAD-ESI-MS/MS technique [1]. 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay has been applied for the determination of the antioxidant activity of the wines and the wine colour was recorded using the CIELab uniform colour space. The major constituents belonging to the five different families found in the wines from all varieties were malvidin-3-glucoside, quercetin-3-glucuronide, trans-caftaric acid, resveratrol-3-glucoside and carboxy-pyrano-malvidin-3-glucoside (vitisin A). Comparing the wines from 2008 vintage, Vranec contained the highest amount of anthocyanins, pyranoanthocyanins, flavonols, hydroxycinnamic acid derivatives and stilbenes, followed by Merlot and Cabernet Sauvignon. A correlation of the antioxidant activity to each of the five groups of phenolic compounds was observed, confirming that the wine antioxidant potential is due to a complex mixture of phenolics