Enoforum 2021
IVES 9 IVES Conference Series 9 Enoforum Web 9 Enoforum Web Conference 2021 9 Cellar session 9 Relation between phenolic content, antioxidant capacity, oxygen consumption rate of diverse tannins

Relation between phenolic content, antioxidant capacity, oxygen consumption rate of diverse tannins

Abstract

The work was aimed at comparing some analytical methods used to characterize oenological tannins and the measure of oxygen consumption rate (OCR), in order to provide oenologists with a rapid method to test the antioxidant capacity of tannin based products and a tool to choose the best suited product for each purpose. Seven tannins with different botanical origin were studied by determining the polyphenolic content (Folin-Ciocalteau assay, GAE%; Total Polyphenols Index, TPI%; Phloroglucinolysis, CT%), antiradical activity (DPPH), reducing capacity (FRAP), redox properties (Linear Sweep Voltammetry, LSV). The OCR was measured with a noninvasive luminescence-based technology in an oxygen saturated model wine solution, containing transition metals and metabisulphite to better simulate the oxidative conditions. The results showed a high variability in polyphenolic content due to the botanical origin of tannins. The OCR determined over 21 days was described by quadratic equations, with coefficients varying with the dose and botanical origin of tannins and with SO2 concentration. The tannins ranked differently for antioxidant capacity, depending on the kind of test. The OCR was correlated with the LSV and FRAP indexes. The Factor Analysis of data distinguished three causes of variability between tannins (3 Factors) and the analytical parameters describing them: 1) the richness in polyphenols (First Factor, explaining the 34.02% of the total data variability), described by GAE%, TPI%, DPPH; 2) the tannin typology (Second Factor, 27.4%), described by LSV and CT%; 3) the oxygen consumption rate (Third Factor, 30.00%), described by OCR, LSV, FRAP.

DOI:

Publication date: April 23, 2021

Issue: Enoforum 2021

Type: Article

Authors

Silvia Mottaa, Massimo Guaitaa, Claudio Cassinob, Antonella Bossoa

a Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria – Centro di Ricerca Viticoltura ed Enologia, via P. Micca 35, 14100 Asti, Italy
b Dipartimento di Scienze e Innovazione Tecnologica, Università degli Studi del Piemonte Orientale, Viale T. Michel 11, 15121 Alessandria, Italy

Contact the author

Tags

Enoforum 2021 | IVES Conference Series

Citation

Related articles…

The impact of acetaldehyde on phenolic evolution of a free-SO2 red wine

Some wine producers, in good years, can produce free-SO2 red wines and decide to add the minimum amount of sulphur dioxide only at bottling. To manage this addition

The effect of pedoclimatic conditions on the yeast assimilable nitrogen concentration on white cv. Doral in Switzerland

Aims: Agroscope investigated the efficiency of nitrogen fertilization via foliar urea application at veraison with the aim of raising the YAN (yeast assimilable nitrogen) content in the musts. The observations were conducted on the white grapevine cultivar Doral (Chasselas x Chardonnay) in several pedoclimatic conditions of the Leman wine region, Switzerland, in the years 2012 and 2013. Knowing that the YAN in must plays a key role in wine quality, the aim was finding the main parameters affecting the final YAN level in order to better control them.

Climate change and viticulture in Nordic Countries and the Helsinki area

The first vineyards in Northern Europe were in Denmark in the 15th century, in the southern parts of Sweden and Finland in the 18th century at 55–60 degrees latitude. The grapes grown there have not been made into wine, but the grapes have been eaten at festive tables. The resurgence of viticulture has started with global warming, and currently the total area of viticulture in the Nordic countries, including Norway, is estimated to be 400–500 hectares, most of which is in Denmark. Southern Finland, like all southern parts of Northern Europe, belongs to the cool-cold winegrowing area.

OPTIMIZING THE IDENTIFICATION OF NEW THIOLS AT TRACE LEVEL IN AGED RED WINES USING NEW OAK WOOD FUNCTIONALISATION STRATEGY

During bottle aging, many thiol compounds are involved in the expression of bouquet of great aged red wines according to the quality of the closure.1,2 Identifying thiol compounds in red wines is a challenging task due several drawbacks including, the complexity of the matrix, the low concentration of these impact compounds and the amount of wine needed.3,4
This work aims to develop a new strategy based on the functionalisation of oak wood organic extracts with H₂S, to produce new thiols, in order to mimic what can happen in red wine during bottle aging. Following this approach and through sensory analysis experiments, we demonstrated that the vanilla-like aroma of fresh oak wood was transformed into intense “meaty” nuances similar to those found in old but non oxidized red wines.

Influence of a spontaneous cover crop on the vineyard and soil erosion under Mediterranean climate

Sixty five % of the agricultural area of the Basque Country located in the DO Ca Rioja corresponds to vineyards. More than 40% of it has an average slope greater than 10%, which makes it sensitive to erosive processes. Furthermore, it is foreseeable that extreme weather events (storms, hail, extreme heat and cold, etc.) will be favored due to climate change. Cover cropping can mitigate this risk, and therefore the objective of this work is to evaluate the impact that a vegetable cover has on the agronomic behavior of the vineyard, the quality of the grape and soil erosion. For this, a trial has been carried out with a Graciano variety vineyard with a slope between 10% -20% during the years 2020 and 2021. Conventional tillage management in the area has been compared (4-6 passes per year of tillage machinery) versus spontaneous vegetation cover management in the vineyard. This implies not tilling and allowing the grass of the land to colonize the range between the lines of vines, controlling their height through 1-3 mowing passes per year, always trying to affect the surface of the land as little as possible. The vegetative growth, yield and quality of the grape and wine was measured. Furthermore, erosion has been measured using Gerlasch boxes. The yield was lower in the second year of the trial in the cover crop treatment, but erosion was significantly reduced.