[Show abstract][Hide abstract] ABSTRACT: Chamber drying under controlled temperature and humidity conditions of the red grape varieties Merlot and Tempranillo grown in Andalusia (Spain), and the fortification and maceration of the musts in the presence of skin from both types of grapes, to obtain sweet red wines, has been studied. Changes in colour and in monomeric and polymeric phenols during the vinification process were examined. Chamber drying increased the sugar content to about 31.4 °Brix within 48 h in Merlot grapes and 72 h in Tempranillo grapes. This drying process also causes skin rupture, facilitating the access of phenolic compounds to the pulp. The resulting musts exhibited slight browning and increased red hues, due to a high concentration of anthocyanins; maceration in the presence of grape skins for 24 h provided the best results. The end-product contained highly acceptable tannin, colour and phenolic compounds for marketing as a high quality sweet red wine, in comparison with other commercial sweet red wines.
[Show abstract][Hide abstract] ABSTRACT: This paper reports on a study of the profiles of different phenolic compounds (anthocyanins, flavonols, hydroxycinnamic acids and stilbenes) of five minor red grape varieties from the Spanish region of Castilla-La Mancha (Bobal, Moravia Agria, Moravia Dulce, Rojal and Tortosí) and a traditional variety from this growing region (Cencibel) as reference. Grape skin extracts of each variety were analysed by High Performance Liquid Chromatography coupled to Diode Array Detector (HPLC–DAD). The content of grape skins in anthocyanins (21.1–453 mg kg−1), flavonols (26.9–288 mg kg−1) and hydroxycinnamic acids (6.80–18.2 mg kg−1) showed differences according to mainly varietal origin, although other important factors have to be taken into account such as the degree of ripeness, berry size or vintage year. In all the studied varieties, the major anthocyanin was malvidin 3-glucoside (>40%) with the exception of Rojal variety, which major one was peonidin 3-glucoside together with cyanidin 3-glucoside. Moravia Dulce and Rojal varieties contained more than 46% of quercetin 3-glucuronide; the rest of them contained less than 27%. No relation was found between profiles of hydroxycinnamic acids in the studied samples and their variety or year of vintage. All the studied grapes presented high concentrations of stilbenes that could be interesting due to the health benefits.
European Food Research and Technology 01/2012; 234(2). · 1.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This paper was aimed at optimizing the extraction conditions for the maximum yield of anthocyanins from Jaboticaba (Myricia Jaboticaba Berg.) skins. Tristimulus colorimetry was applied to evaluate quantitatively and qualitatively the process. A mixed 2 and 3 full factorial design was used (21 · 33). The factors and levels studied were type of solvent: ethanol or methanol; solvent/water mixture: 100% v/v, 90% v/v, 80% v/v; type of acid: clorhidric acid, citric acid or acetic acid and pH: 2, 3 or 4. The estimated effect and ANOVA parameters were calculated. The yield of anthocyanins, quantified following an spectrophotometric method based on the absorbance at 535 nm was 92.92 ± mg/kg of skin. The yield of anthocyanins showed a high and significant correlation with chroma () (p < 0.05; r = 0.84) and lightness (L*) (p < 0.05; r = −0.85) and it was significantly (p < 0.001) affected by the type of acid used and the solvent/water% (p < 0.05).
Food Research International 10/2005; · 3.05 Impact Factor
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