Identification and changes of flavonoids in Merlot and Cabernet Sauvignon wines. J Food Sci
ABSTRACT Twenty components of an ethyl acetate extract from Merlot and Cabernet Sauvignon wines were isolated by recycle preparative HPLC. A combination of paper chromatography, fluorescence behavior, gas chromatography, reaction with molybdate, reaction with vanillin/HCI, ultraviolet spectrometry and mass spectrometry was used to gain information about the identities of the isolated compounds. Seven of the isolated compounds were catechins, procyanidins or degradation products thereof. Three flavonol glycosides were isolated and one was characterized as an isorhamnetin-3-glycoside. Four compounds were isolated with identical molecular weights and an uncharacteristic blue reaction with vanillin/HCl. These components were interconvertable and thought to be cis-trans isomers of flavenes. The changes in these components during aging of Merlot and Cabernet Sauvignon wines are discussed.
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- "In order to characterize the products of degradation of ANC owing to industrial treatment of juices, further experiments with NaHSO 3 (Somers & Evans, 1977; Wulf & Nagel, 1980; Glories, 1984; Azar et al., 1987) were attempted. NaHSO 3 allowed the degree of degradation of the pigments and of the quantity of polymers to be estimated by comparison of OD 520 before and after the action of an aqueous solution of NaHSO 3 (50% v/v) on the different juices FPJ, RJ and SJ. "
ABSTRACT: Summary The degradation of anthocyanic pigments of fresh and industrial juices from blood oranges were studied during storage periods of a few days at −18 °C and 12 months at 4 °C in nitrogen. The change of anthocyanin pigments was followed by HPLC at 520 nm while the coloured polymeric pigments were fractionated by chromatography and characterized by their transformation indices and their reactivity with NaHSO3. The results show that the process of polymerization is accompanied by production of chemical indicators of sugar and ascorbic acid degradation (furfural and hydroxymethylfurfural). It seems that the resulting polymeric compounds have structures different from those of the compounds formed during wine processing. Reactions between anthocyanic pigments and the intermediates of degradation of sugar and ascorbic acid in an acidic environment are the main causes of formation of these polymers.International Journal of Food Science & Technology 12/2001; 35(3):275 - 283. DOI:10.1046/j.1365-2621.2000.00330.x · 1.35 Impact Factor
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- "grapes, mainly in the skin (Wulf and Nagel, 1980; Cheynier and Rigaud, 1986) in the monoglycoside form, with the sugar residue linked to the hydroxyl group mainly in position C-3 of the O-containing ring. "
ABSTRACT: The recovery of high added-value products from waste plant material has been an important issue with economic relevance for the pharmaceutical and food industries. The recovery of antioxidants from wine industry by-products is of great importance in the nutraceutical field. The aim of this study was to identify the main flavonol glycosides, present in winemaking by-products from two white grape varieties: Arinto and Moscatel using liquid chromatography with diode array and electrochemical detection. Liquid chromatography with electrospray and atmospheric pressure chemical ionization, in negative and positive modes, were also used to characterize the structures of the compounds detected by means of MS 2 and MS 3 . In the by-products analysed quercetin-3-glucoside and quercetin-3-glucuronide were identified as well as kaempferol-3-glucoside. By-products from Arinto variety showed higher levels of quercetin glycosides and kaempferol-3-glucoside than the by-products of Moscatel variety.
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ABSTRACT: Three white table wines were treated with additions of purified anthocyanins at 0, 250, and 500 mg/L and 0, 500, and 1000 mg GAE/L of grape-seed tannin in all possible combinations. The results of analyses for polymeric phenols were very consistent with the different wines and show that anthocyanins quickly complex with polymeric phenolic tannins to retain them in solution. The lack of such complexing explains why wines made from white grapes by red vinification methods are deficient in tannins and astringency. These anthocyanin- tannin complexes that form quickly in red wine differ from those produced by aging in remaining relatively adsorbable by Sephadex LH-20. These results have important implications for red wine astringency and other quality and processing characteristics.