Two commercially available maceration enzymes and two enological tannins were tested in Monastrell wines to determine their suitability for improving the chromatic characteristics, colour stability and sensory properties of the resulting wines. The greatest differences for all the wines, when comparing with the control wine, were observed at the beginning of the winemaking process, any differences diminishing in the finished wines. One of the enzymetreated wines was used showed hardly any difference from the control wine, whereas the other enzyme-treated wine showed an improvement in their chromatic and sensory characteristics. The use of two different enological tannins did not provide any improvement in the chromatic and sensory characteristics of the wines, imparting a higher yellow colour and resulting in lower scores in the colour and aroma sensory characteristics, accompanied by a higher astringency, dryness and bitter sensory sensations.

Proanthocyanidins are important for wine quality since they participate in astringency, bitterness and color. Given the localization of proanthocyanidins in the berry (skin and seeds), different methods have been developed that help to modulate the release of these phenolic compounds. In this study, the effect of two low prefermentative temperature techniques (cold soak and must freezing with dry ice) and the use of macerating enzymes has been studied during the vinification of three different varietal wines (Monastrell, Syrah and Cabernet Sauvignon) to assess their influence on wine proanthocyanidin concentration and composition. Syrah wines showed the lowest proanthocyanidin content, together with the lowest mDP and the highest percentage of galloylation in its proanthocyanidins. Monastrell and Cabernet Sauvignon wines showed similar proanthocyanidin concentration. The application of the low temperature prefermentative maceration (cold soak) was the most effective treatment, increasing the proanthocyanidin concentration in Monastrell and Cabernet Sauvignon wines although neither of the treatments had any effect on Syrah wines. As regards the effect of the different treatments on the proanthocyanidin composition, the results seem to indicate that the observed increases were mainly due to an increase in seed proanthocyanidins, even in the case of cold soak treatments, which occur in the absence of ethanol, suggesting that ethanol is not so crucial in the extraction of seed proanthocyanidins.

BACKGROUND: Grape skin cell walls form a barrier against the diffusion of colour. The colour of red wines is mainly due to anthocyanins, although their concentration in wine is not always correlated with the anthocyanin content of grape skins. The cell wall composition changes during fruit ripening, so it was thought that a study of the ripening behaviour of four premium varieties might provide information on how the composition changes during ripening and explain the technological differences.

Edible flowers are commonly used in human nutrition and their consumption has increased in recent years. The aim of this study was to ascertain the nutritional composition and the content and profile of phenolic compounds of three edible flowers, monks cress (Tropaeolum majus), marigold (Tagetes erecta) and paracress (Spilanthes oleracea), and to determine the relationship between the presence of phenolic compounds and the antioxidant capacity. Proximate composition, total dietary fibre (TDF) and minerals were analysed according to official methods: total phenolic compounds (TPC) were determined with Folin-Ciocalteu’s reagent, whereas antioxidant capacity was evaluated using Trolox Equivalent Antioxidant Capacity (TEAC) and Oxygen Radical Absorbance Capacity (ORAC) assays. In addition, phenolic compounds were characterised by HPLC-DAD-MSn. In relation to the nutritional value, the edible flowers had a composition similar to that of other plant foods, with a high water and TDF content, low protein content and very low proportion of total fat—showing significant differences among samples. The levels of TPC compounds and the antioxidant capacity were significantly higher in T. erecta, followed by S. oleracea and T. majus. Thirty-nine different phenolic compounds were tentatively identified, with flavonols being the major compounds detected in all samples, followed by anthocyanins and hydroxycynnamic acid derivatives. In T. erecta small proportions of gallotannin and ellagic acid were also identified.

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The effect of three enological techniques (low temperature prefermentative maceration, must freezing with dry ice, and the use of a maceration enzyme) on the extraction of anthocyanins and proanthocyanidins from must to wine during fermentative maceration was studied to determine the extent to which these compounds are extracted and to assess the changes on their qualitative composition due to enological technique applied. The results showed that the dry ice treatment led to wines with high color intensity and high anthocyanin content, the maximum rate of extraction being observed the first 6 days of fermentative maceration. Regarding the effect of the different techniques on the quantitative and qualitative composition of proanthocyanidins, only the dry ice treatment seemed to favor the extraction of high molecular weight skin proanthocyanidins. The low temperature prefermentative maceration treatment led to the highest concentration of proanthocyanidins at the moment of pressing; however, this treatment, contrary to expectations, led to wines with the highest content of seed-derived proanthocyanidins. The use of the maceration enzyme also increased the concentration of proanthocyanidins during all of the fermentative process, as compared to a control wine, although the increase was not only due to skin proanthocyanidins but also seed proanthocyanidins. We have demonstrated in this study that maceration enzymes also facilitate seed phenolic extraction.

Background and Aims:The evolution of seed tannins in three grape varieties grown in the same vineyard was followed from preveraison to harvest, to determine their pattern of accumulation. Also, to elucidate whether the use of 70% acetone as extracting solvent overestimate what will occur during fermentation, seed tannins were extracted throughout the ripening period with a method that involved a 3 days extraction with aqueous 12.5% ethanol and the results compared with the acetone extraction method. Methods and Results: For both methods, the extracted tannins were analysed following acid-catalysis in the presence of excess of phloroglucinol. Seed tannins reached a maximum around veraison and decreased towards maturity, the mean degree of polymerization (mDP) varying only slightly during the studied period. When tannins were extracted with 12.5% ethanol, their concentration was much higher during the first part of the maturation than using acetone but was significantly lower at harvest. Conclusions: The decrease in extractable seed tannins during ripening was observed with both solvents. The differences observed in the concentration of tannins with both solvents could be due to the histochemical changes occurring in seeds during maturation. Significance of the Study: The differences observed in tannin concentration with the two different methods may indicate that when pulp maturity is reached before seeds are ripe, the fermenting solution will extract more tannins than the acetone method. These results point to the importance of extraction methodology when monitoring seed maturity for the prediction of seed tannins in wine.