 IVES 9 IVES Conference Series 9 Analysis of voltammetric fingerprints of different white grape musts reveals genotype-related oxidation patterns

Analysis of voltammetric fingerprints of different white grape musts reveals genotype-related oxidation patterns

Abstract

Must oxidation is a complex process involving multiple enzymatic transformations, including the oxidation of phenolics containing an ortho-diphenol function. The latter process has a primary influence on wine aroma characteristics and stability, due to the central role of ortho-diphenols in the non-enzymatic oxidative reactions taking place during winemaking and in finished wine. Although oxidation of must is traditionally avoided, in recent years its contribution to wine quality has been revisited, and in some cases improvements to wine aroma have been observed with the application of controlled must oxidation. Nowadays there is a great interest in the wine industry towards the identification of specific markers or patterns to characterize and classify the response of grape must to oxidation. In this study, the response of several grape genotypes to application of controlled doses of oxygen was investigated over three consecutive vintages. Healthy grapes were harvested at maturity form a single experimental vineyard and crushed in controlled conditions. The must obtained was submitted to three consecutive oxygen saturations (approx. 8 mg/L of oxygen). Oxygen consumption kinetics were measured using a chemioluminescence multisensor apparatus. Upon consumption of each saturation, samples were submitted to spectrophotometric analyses to assess oxidation-induced changes to relevant parameters such as absorbance at 280 nm, 320 nm and 420 nm. Voltammetric analyses were also carried out using a Nomasense Polyscan potentiostat with screen printed electrodes to assess the evolution of the entire must oxidizable fraction, including ortho-diphenols. Depending on the vintage, between four and eight genotypes were analyzed, with each oxidation experiment carried out in four replicates. Oxygen consumption rates varied considerably among samples and vintages. Genotypes could be divided in slow (0.07-0.17 mg/L/min) and fast (0.35-0.43 mg/L/min) oxygen consuming, and this was not clearly associate with Folin-Ciocalteu index. Minor changes were observed at the end of each oxidation cycle for UV-Vis parameters such as Abs 280 and 320, while Abs 420 generally increased, in particular during the 2015 trial. Electrochemical analysis revealed major changes in the content and profile of oxidizable compounds, which decreased with each oxidation cycle. The patterns of such changes, namely the regions of the voltammogram mostly affected by oxidation, were found to be genotype-dependent, with vintage only having a minor influence. Specific oxidation patterns could be associated with either slow or fast oxygen consuming musts. These data indicate that the response of grape must to oxidation is linked to specific compositional characteristics (phenolic profiles, enzymes etc) which can be more effectively investigated and controlled by electrochemical methods rather than conventional spectrophotometric approaches.

Publication date: May 17, 2024

Issue: Macrowine 2016

Type: Poster

Authors

Maurizio Ugliano*, Jean Baptiste Dieval, Nelly Champeau, Stephane Vidal, Stephanie Begrand

*University of Verona

Contact the author

Citation

Comparison of fortified, sfursat and passito winemaking techniques for the enhancement of the oenological potential of the black grape cultivar Moscato nero d’Acqui (Vitis vinifera L.)

One of the key factors of the economical development of viticulture and wine industry in specific limited areas is the exploitation of ancient, local grape varieties. Therefore, in recent years the growing interest to rediscover minor varieties, previously cultivated, has promoted many studies. With this regard, the focus of this study was the Vitis vinifera L. cultivar Moscato nero d’Acqui, nowadays found only in old vineyards in the Acqui zone (North-West Italy). In particular, the aims of this work were: i) to investigate secondary metabolites profile of the grapes, and ii) to evaluate the attitude to the production of special wines.

Multivariate strategies for red wines classification using stilbenes and flavonols content

Bioactive polyphenols from grapes and wines, like stilbenes and flavonols (SaF), are often determined to nutritional evaluation, but also for many other purposes. The objective of this study was to quantify SaF in red wines from “Campanha Gaúcha”, a large and young viticultural region from South Brazil. Moreover, through statistical analysis, evaluate the influence of these compounds according to varieties, production process, harvest years and micro-regions of cultivation. A total of 58 samples of red wines were analyzed by high-performance liquid chromatography coupled to diode array detector (HPLC-DAD) for determination of trans-resveratrol (R), quercetin (Q), myricetin (M), kaempferol (K), trans-e-viniferin (V) and their precursor, cinnamic acid (C).

Removal of Fumonisin B1 and B2 from red wine using polymeric substances

The Ability of PVPP (Polyvinylpolypyrrolidone), PVP-DEGMA-TAIC (copolimerization of N-vinyl-2-pyrrolidinone with ethylene glycol dimethacrylate and triallyl isocyanurate) and PAEGDMA
(poly(acrylamide-co-ethylene glycol dimethacrylate)) polymers was tested as removal agents for Fumonisin B1 (FB1) and Fumonisin B2 (FB2) from model solutions and red wine. The polymers removal capacity was checked at three different resident times (2, 8 and 24 hours of contact time between the polymer and the sample), showing no differences in the percentage of FB1 and FB2 removal. Then, different polymer concentrations (1, 5 and 10 mg mL-1) were tested in model solution with and without phenolics (i.e. gallic acid and 4-methylcatechol).

Molecular cloning and characterization of UDP-glucose: furaneol glucosyltransferase gene from Japanese

2,5-Dimethyl-4-hydroxy-3(2H)-furanone (furaneol) is an important aroma compound in fruits, such as pineapple and strawberry, and is reported to contribute to the strawberry-like note in some wines. Several grapevine species are used in winemaking, and furaneol is one of the characteristic aroma compounds in wines made from American grape (Vitis labrusca) and its hybrid grape, similar to methyl anthranilate. Muscat Bailey A is a hybrid grape variety [V. labrusca (Bailey) x V. vinifera (Muscat Hamburg)], and its wine is one of the most popular in Japan. The inclusion of Muscat Bailey A in the ‘International List of Vine and Varieties and their Synonyms’ managed by the ‘International Organisation of Vine and Wine (OIV)’ in 2013 has further fueled its popularity among winemakers and researchers worldwide.

Sensory impacts of the obturator used for the Chasselas: study over the time

Many parameters affect the organoleptic characteristics of wine: internal parameters like the chemical composition or polyphenol content and external as for example storage conditions or the type of obturator. The aim of this study was to characterize sensorally the impacts of several type of obturator on a white wine: Chasselas. To determine the organoleptic characteristics of this wine, a quantitative descriptive analysis could be used. But rapid sensory methods were preferred in this project. Indeed these methods are an appropriate alternative to conventional descriptive methods for quickly assessing sensory product discrimination.