Horst Nowosad

From the press to the bottle

How much nitrogen does a good wine need? There is now a definite answer for the Sauvignon Blanc grape: during pressing, vinification and, of course, bottling. In the food industry, nitrogen is used in the storage of fresh products, for protection purposes during production and for packaging. The use of nitrogen as a means of preventing unwanted oxidation is tried and tested and ensures value-preserving wine production.

The Sauvignon Blanc grape is not at all a fan of oxidation. This is known and leads to the loss of aroma and to unpleasant discolouration in yellow and brown tones. This grape variety was therefore removed in order to examine the benefits of consistent inertisation vis-à-vis only partial nitrogen atmospheres or atmospheres that do not contain any nitrogen at all. In an environmentally friendly manner, the natural gas nitrogen can be easily generated and, if necessary, generated on-site from the ambient air using a nitrogen generator.

The use of inert gas presses, such as the Scharfenberger Europress Ti52, is relatively new in wine press technology. It is most beneficial with grapes sensitive to oxidation.

Standard & inert gas presses

Prof Dr Dominik Durner from Weincampus Neustadt at the Dienstleistungszentrum Ländlicher Raum Rheinpfalz led the controlled trial in which three batches of grapes were processed with standard and inert gas presses (Scharfenberger). A portion of the must was then turned into wine through reductive procedures, i.e. still in the absence of oxygen.

Another portion of the must was processed normally which involved contact with atmospheric oxygen. A partial quantity of this portion was in turn treated with ascorbic acid. This is a conventional method of extracting oxygen from the wine.

The comparison of consistent inert production and standard production revealed clear benefits for all three wines: A higher content of aromatic substances, which could clearly be shown in relation to consistent inert processing of the grape until reaching the bottle.

Assessment of the aroma & flavour

When using the inert gas press, there is not only a higher content of aromatic substances, but also a higher phenolic content. This increase in phenols makes it even more important that the must and subsequent wine continue to be processed in the absence of oxygen. If the phenols do not oxidise, the Sauvignon Blanc remains clear and no high chromaticity occurs such as that which wine producers call the yellow and brown discolouration untypical of the grape.

However, it is not just the colour that benefits, the flavour wins as well with nitrogen: If it is pressed inertly, the must contains more glutathione, an antioxidant that benefits yeast vitality during fermentation. Glutathione furthermore protects valuable aromas and results in improved storage stability for the bottled wines. All of the wines from the trial were presented to qualified wine tasters at a blind tasting six weeks after bottling. These wine tasters rated the aroma and flavour using a standardised questionnaire.

This revealed that the wine which had been completely produced in a nitrogen atmosphere was perceived as especially aromatic (high degree of minerality, lemon aromas, green pepper and exotic fruits). The wine, which was only pressed inertly but matured in a normal atmosphere, lost these characteristics due to contact with 02.

The tasters rated the inertly pressed and the inertly vinified wines as typical of the Sauvignon Blanc grape. The latter was mainly expressed when tasting was repeated after one and a half years. The distinctive character of the Sauvignon Blancs that were not consistently, inertly vinified was rated significantly lower in this regard.

Consistent nitrogen treatment makes it possible to create particularly fresh, clear and qualitatively improved white wines. This is hereby proven for the Sauvignon Blanc grape sensitive to oxidation.

INMATEC has decades of experience with nitrogen for the food and drink industry and offers freedom from tanks, bundles, bottles and supply shortages thanks to direct nitrogen generation.

INMATEC & Scharfenberger Machines
INMATEC & Scharfenberger Machines

Image caption 1: INMATEC nitrogen generators with touch control panel Image caption 2: Scharfenberger inert gas press Europress Ti52

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