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Anthocyanins are important compounds for red grape and red wine quality, and can be influenced by supply of nutrients such as nitrogen, phosphorus, potassium, zinc, and iron. The present work aims to gain a better understanding of the effect of iron supply on anthocyanins concentration in grape berries. To this end, own-rooted four-year-old Cabernet Sauvignon grapevines (Vitis vinifera) were fertigated every three days with 0, 23, 46, 92, and 184 μM iron (Fe) from ferric ethylenediamine di (o-hydroxyphenylacetic) acid (Fe-EDDHA) in a complete nutrient solution. Fe deficiency or excess generally led to higher concentrations of titratable acidity and skin/berry ratio, and to lower reducing sugar content, sugar/acid ratio, pH, berry weight, and concentration of anthocyanins. Most of the individual anthocyanins detected in this study, except cyanidin-3-O-glucoside, delphinidin-3-O-glucoside, and cyanidin-3-O-(6-O-coumaryl)-glucoside, in moderate Fe treatment (46 μM) grapes were significantly higher than those of other treatments. Genes encoding chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), leucoanthocyanidin dioxygenase (LDOX), and anthocyanin O-methyltransferase (AOMT) exhibited higher transcript levels in berries from plants cultivated with 46 μM Fe compared to the ones cultivated with other Fe concentrations. We suggest that grape sugar content, anthocyanins content, and transcriptions of genes involved in anthocyanin biosynthesis were correlated with Fe supply concentrations.

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The phenolic compounds in the grape skins of Cabernet Sauvignon (CS), Merlot (ML), Syrah (SY) and Marselan (MS) from Shacheng, in China, were compared using HPLC-MS/MS. The results showed that the types and levels of phenolic compounds varied greatly with cultivars. Malvidin derivatives were the main anthocyanins. CS and ML showed a higher content of malvidin-3-O-(6-O-acetyl)-glucoside than malvidin-3-O-(trans-6-O-coumaryl)-glucoside, while SY and MS differed from CS and ML. ML had higher delphinidin and cyanidin derivatives, SY had higher peonidin derivatives, while malvidin and petunidin were higher in MS. The total content of flavonols, flavan-3-ols, phenolic acids and stilbenes in grape skins showed no difference among CS, ML and MS. Isorhamnetin-3-O-glucoside (CS, ML, MY), quercetin-3-O-glucoside (SY), procyanidin trimer (SY, MS), procyanidin dimer (CS, ML), syringetin-3-O-glucoside, trans-cinnamic acid and resveratrol were the most abundant non-anthocyanin phenolic compounds. Cluster analysis showed that CS and ML, and SY and MS had similar phenolic profiles. INTRODUCTIONPhenolic compounds in red grape skins are one of the most important parameters in determining red wine character and quality, and directly influence consumers' overall acceptance (Li et al., 2011). They contribute to the mouthfeel, colour and stability of red wines; some of them also exhibit potent biological activities (Gómez-Alonso et al., 2007). Phenolic compounds, mostly originating from grape berries, are transferred into wine during the winemaking process (Salas et al., 2003). The main phenolic compounds in red grapes and red wine are anthocyanins and non-anthocyanins, which include flavonols, flavan-3-ols, phenolic acids (including hydroxycinnamic acids and hydroxybenzoic acids) and stilbenes (Monagas et al., 2005;Li et al., 2011;Zhang et al., 2015). Anthocyanins, which are directly responsible for red grape and red wine colour (Mateus et al., 2002;Revilla et al., 2009), are composed of the monoglucosides of five anthocyanidins, namely delphinidin, cyanidin, petunidin, peonidin and malvidin, along with the corresponding acetyl, p-coumaroyl and caffeoyl derivatives (Liang et al., 2008;Raúl et al., 2009). Flavonols, which influence red wine coloration by co-pigmentation (Boulton, 2001), consist of the glycosides of myricetin, quercetin, kaempferol, isorhamnetin, syringetin and laricitrin (Raúl et al., 2009). The flavan-3-ols found in the skin and seed are mainly catechin, epicatechin, gallocatechin, epigallocatechin and their corresponding polymers. Flavan-3-ols are mainly responsible for the astringency, bitterness and structure of wines (Monagas et al., 2005), and they also play an important role in the stabilization of the red colour in wines (Sun et al., 2007). Stilbenes (mainly resveratrol) exhibit significant antioxidant properties in the prevention of arteriosclerosis and coronary heart disease (Sun et al., 2002).The amount of phenolic compounds in grapes is influenced by the grape variety, along with viticultural and environme...

The aim of this paper was to investigate how maturity affects the aroma characteristics of Cabernet Sauvignon wine. A series of four Vitis vinifera cv. Cabernet Sauvignon wines were produced from grapes of different harvest dates. The berries of sequential harvest treatments showed an increase in total soluble solids and anthocyanin and a decrease in titratable acidity. Berry shriveling was observed as berry weight decreased. In the wines, anthocyanin, dry extract, alcoholic strength, and pH were enhanced with the sequential harvest, whereas polyphenol and tannin were decreased. The concentrations of volatile compounds in sequential harvests were found to be at higher levels. Isopentanol, phenylethyl alcohol, ethyl acetate, ethyl lactate, benzaldehyde, citronellol, and linalool significantly increased when harvest was delayed by one or two weeks. Through a principal component analysis, the volatile compounds and phenols characterizing each harvest date were clearly differentiated. These results suggest that sequential harvest may be an optional strategy for winemakers to produce high-quality wine.

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