Study of the “Charentes terroir” for wine production of Merlot and Sauvignon: method, installation of the experimental device, first results

The aim of the study was to study the volatile substances and ellagitannins released to wine by barrels of Quercus pyrenaica (Spanish Oak) in comparison with barrels of Quercus petraea (French Oak) and Quercus alba (American Oak) as well as to determine their sensory impact.

Table grape production requires adequate nitrogen (N) supply to sustain vine performance and obtain high yields. However, excess agricultural N fertilization is a major source of groundwater contamination and air pollution. Therefore, there is a strong need for empirically based precision N fertilization schemes in vineyards, for optimizing grape yield and quality while minimizing their environmental impact.
Our aim was to unequivocally quantify table grape N requirements, elucidate the drivers of daily N uptake, and quantify the relationship between fertigation N levels and vine growth, fruit yield, composition, and quality. For this, forty ‘Early Sweet’ (early-maturing, white) and ‘Crimson seedless’ (late-maturing, red) vines were grown in 500L drainage-lysimeters for 2 fruiting seasons, while subjected to five continuous N fertigation treatments ranging from 10 to 200 ppm.

Global climate change is exerting a notable influence on viticulture sector and grape composition. The increase in temperature and the changes in rainfall pattern are causing a gap between phenolic and technological grape maturities [1]. As a result, the composition of grapes at harvest time and, consequently, that of wines are being affected, especially with regards to phenolic composition. Hence, wine quality is decreasing due to changes in the organoleptic properties, such as color and astringency, making necessary to implement new adaptive technologies in wineries to modulate these properties in order to improve wine quality.

Gum arabic is composed of a polysaccharide rich in galactose and arabinose along with a small protein fraction [1, 2], which gives its stabilizing power with respect to the coloring substances or tartaric precipitation of bottled wine. It is a gummy exudation from Acacia trees; the products used in enology have two possible botanical origins, i.e. Acacia seyal and Acacia senegal, with different chemical-physical features and consequently different technological effects on wines. The aim of this work is to evaluate the feasibility of discrimination of commercial gums Arabic between their two different sources, on the basis of the absorption of the Fourier Transform Infrared (FT-IR) spectra of their aqueous solutions, in order to propose an extremely rapid and cost-saving method for quality control laboratories.

An intelligent packaging might, among others, provide information and allow monitoring of the quality of the packed product or its surrounding environment. A recent project on micro-flow wine bottles closed with aluminium screw cap and tightness liner, highlighted the importance of monitoring the internal overpressure continuously, in real-time and at least for 72 hours, since the internal pressure on the tightness liner and the micro-flow are related. Real-time and continuous measurements are not the standard methods of measurement of the overpressure, yet. The most used equipment for the determination of the pressure in wine bottle is the aphrometer, a destructive device that supplies a single value of pressure.