Etude de la composition lipidique du raisin, Vitis vinifera L.: Evolution au cours de la maturation et localisation dans la baie

Lipid composition of grapevine berries, Vitis vinifera L.:Changes during maturation and localization in the berryQuantitative determinations in four grapevine varieties, Vitis vinifera L., gave evidence that the level of fatty acids in mature be rries was around 0.045 %, for t he main part unsaturated acids. Linoleic, pa lmit ic, linolenic and oleic acids were the most abundant, followed by stearic and behenic acids . No free fatty acids were found. Phospholipids formed the largest fraction prior to neutral and glycolipids. Glycolipids showed a high level of linolenic acid, while in phospho- and neutral lipids linoleic acid was highest. In the three fractions, polyunsaturated acids made up more th an half of total fatty acids. No differences were found between grape varieties. During grape maturation, changes in fatty acid levels were low, except for linolenic acid, which decreased consistently, this decline was concerned with neutral and glycolipids. Consequently, the potential of herbaceous flavour decreased progressively during berry maturation. Fatty acids were 1.5-3 times lower in pulp than in skin; thus, the skin can contribute to a large enrichment of fatty acids in juice, polyunsaturated derivatives, especially linolenic acid, being highest. In consequence, the presence of a !a rge part of grape herbaceous flavour potential in the skin was confirmed. Fatty acid patterns were s imilar in pulp and in skin, with more than half consisting of polyunsaturated compounds. There were a lso identical patterns for other lipids such as phospholipids, which were t he most abundant, followed by neutral and glycolipids

La macération pelliculaire dans la vinification en blanc - Incidence sur la composante volatile des vins

Skin contact in white wine processing- Effects on the volatile constituents of winesWines were made from three different white vine cultivars, Chenin, Chardonnay, Bourboulenc by standard white wine processing, with and without skin contact, and their volatile constituents were analysed using gas chromatography standard procedures. 61 substances were identified and quantified in quadruplicate. One-way analyses of variance for each component were performed in which skin contact wine was compared to the control wine for each vine cultivar. Skin contact was shown to increase significantly most volatile components except volatile acids. In attempt to classify the wines investigated, principal component analysis was conducted using the amounts of compounds differing significantly in variance analysis

Etude des caroténoїdes du raisin à maturité

High performance liquid chromatography was used to separate the carotenoidcompounds in grapevine be rries. By comparison with standards prepared by thin-layer-chromatography, β-carotene, lutein, 5,6-epoxy lutein, violaxanthin and neoxanthin were identified. Quantitative determination in 13 varie ties of Vitis vinifera L. gave evidence that, in mature berries , thecarotenoid contents can vary between 0.8 and 2.5 mg/kg of fresh we ight, according to variety. ß-carotene and lutein were present in larger quantities than the other carotenoids . The relative contents of each pigment were different from those of other fruits and resembled to those of leaves. Moreover, carotenoids were determined during 2 years in 2 varieties, Carignane and Sirah, grown in 8 different geographic sites