Impact of (+)-catechin and gallic acid on sensory perception and volatility of isoamyl acetate, ethyl isobutyrate, ethyl butyrate and ethyl octanoate was investigated in model solutions, by means of triangle tests, detection threshold determination and HS-GC-MS analyses. Catechin significantly altered the sensory perception of most esters (ethyl isobutyrate, ethyl butyrate and ethyl octanoate) while gallic acid displayed no impact. Ethyl butyrate and ethyl octanoate odour thresholds doubled or tripled in the presence of catechin, underlining a retention impact of phenolic compounds in liquid matrix.
View Article and Find Full Text PDFGrape and wine phenolics are structurally diverse, from simple molecules to oligomers and polymers usually designated as tannins. They have an important impact on the organoleptic properties of wines, that's why their analysis and quantification are of primordial importance. The extraction of phenolics from grapes and from wines is the first step involved in the analysis.
View Article and Find Full Text PDFThe gastric tract may be the first site where food is exposed to postprandial oxidative stress and antioxidant activity by plant micronutrients. After food intake, dietary iron, dioxygen, and emulsified lipids come into close contact and lipid oxidation may take place. This study investigated lipid oxidation and its inhibition by dietary polyphenols in gastric-like conditions.
View Article and Find Full Text PDFCabernet-Sauvignon and Merlot skin and seed extracts from Bordeaux grapes were investigated to determine both grape variety and vintage effect on phenolic composition. The total content of polyphenols and tannins in Merlot seeds was higher than that of Cabernet-Sauvignon allowing to discriminate the varieties. HPLC analyses underlined significant differences in the absolute concentration of proanthocyanidins amongst the two varieties and in their composition: mean degree of polymerisation (mDP) and percentage of galloylation of seed extracts were good indicators of grape variety.
View Article and Find Full Text PDFThe proanthocyandin composition of skins and seeds of Bordeaux Merlot (M) and Cabernet Sauvignon (CS) grapes was evaluated by HPLC-UV-fluorescence for four consecutive vintages (2006 to 2009). The results indicated a strong vintage effect on the tannin profile of each variety. However, and in spite of the vintage effect, some tannin characteristics such as mDP, %G and %P allow discrimination of both Bordeaux varieties.
View Article and Find Full Text PDFThe antioxidant activity of eight synthetic 4-methylcoumarins was systematically studied. The antioxidant capacity was measured using: (i) a competition kinetic test, to measure the relative capacity to quench peroxyl radical; (ii) the in vitro oxidative modification of human low-density lipoprotein, initiated by AAPH or catalyzed by copper. In both models, the ortho-OH substitutes were found to be better antioxidant than the meta one.
View Article and Find Full Text PDFMetmyoglobin (MbFe(III)), a major form of dietary iron, is an efficient inducer of lipid and protein oxidation. Indeed, MbFe(III) is able to cleave hydrogen peroxide and lipid hydroperoxides with subsequent formation of ferrylmyoglobin (MbFe(IV)=O) and lipid oxyl and peroxyl radicals. In the first part of this work, the mechanism of the reaction between MbFe(III) and H(2)O(2) is revisited with an emphasis on the influence of bovine serum albumin (BSA).
View Article and Find Full Text PDFThe gastric tract may be the first site exposed to diet-related oxidative stress. After food intake, dietary iron such as (met)myoglobin, the pigment of meat, oxygen, and polyunsaturated lipids come into close contact. The main goal of this work is the in vitro investigation of lipid oxidation taking place in the gastric compartment and its inhibition by dietary polyphenols.
View Article and Find Full Text PDFThe aim of the present study was to validate the joint sensory impact of target compounds on the typicality degree of wine. Target compounds were selected from previous gas chromatography-olfactometry analysis. The preliminary experiment consisted in selecting odorants thought to have a positive effect on typical Chardonnay wines.
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