Terroir Hesse – Soil determines wine style

Chemical and sensory changes occurring in red wine during ageing in oak barrique are due to the slow and gradual entrance of oxygen along with a release of ellagic tannin from the wood. Though oxygen can enter the cask through the bunghole, it is not clear the role of permeation through the wood staves as well as the amount of oxygen entering by permeation. The distribution of the released ellagic tannins in the wine ageing is also unknown. The oxygen passing through the bunghole may have a different wine ageing effect compared to the oxygen permeating through the wooden staves owing to the uneven ellagic tannin concentration throughout the wine.

AIM AND METHODS: Grape withering is one of the key steps in the production of the most renowned red wines of the Valpolicella area, namely Amarone and Recioto. This practice, which was already used since Roman times, entails important modifications in grape composition and in the chemical and sensorial characteristics of the corresponding wines, especially in terms of aromatic profile. The aim of this research is evaluating the aromatic evolution during grape withering of the three main varieties used in Valpolicella wines: Corvina, Corvinone and Rondinella.Samples of the three varieties were analyzed at harvest and at different stages of withering, namely10%, 20% and 30% of weight loss. Free and glycosidically bound compounds were extracted and analyzed using Gas Chromatography- Mass Spectrometry (GC-MS). RESULTS: For all the samples the data were normalized to eliminate the effect of concentration due to grape dehydration. Terpene content and evolution varied considerably in relationship to grape variety. Corvinone was richer in cyclic terpenes (including phellandrene, limonene, and cymene) and they decreased during withering.

For many years, enological research has developed commercial formulates of yeast derivatives as stabilizing agents and technological adjuvants in winemaking. These products are obtained from yeast by autolytic, plasmolytic, or hydrolytic processes that liberate many macromolecules from the yeast cell, principally polysaccharides and oligosaccharides and most specifically mannoproteins that are well known for their ability to improve tartaric stability and to reduce the occurrence of protein hazes (Ángeles Pozo-Bayón et al., 2009; Charpentier & Feuillat, 1992; Morata et al., 2018; Palomero et al., 2009).

In the context of the three global crises of global warming, loss of biodiversity and environmental pollution, current agricultural practices need to be reconsidered [1]. Viticulture in particular can contribute to this by optimising plant protection [2].

Context and purpose of the study. Ráthay is an Austrian red quality wine variety with increased resistance to fungi.