Which heat test really represents the haze risk of a white Sauvignon wine ?

3-Mercaptohexanol (3MH) is a volatile thiol occurring in several white and red wines, where it can contribute to fruity attributes. Its content is typically high in wines from certain grape varieties, in particular Sauvignon blanc, where it is considered a varietal marker. The strong nucleophilic character of thiols makes 3MH rather unstable during wine storage, due to the presence of several strong electrophilic species. Among these electrophilics, those arising from the oxidation of flavan3-ols such as catechin and epi-catechin have been indicated as critical for 3MH stability. Accordingly, there is a generalized interest towards the ability of vinification practices to reduce 3MH loss during aging through the management of wine flavan-3-ols content.

Aim: Evaluating the effects of high amount of air injection during red wine fermentation process, on phenolic extraction dynamics, oxygen dissolution, phenolic compounds evolution, and oxidation of red wines.MethodsRed grapes musts were fermented in 100.000 L stainless steel tank, equipped with Parsec SRL “Air mixing” gas injection systems. For this experiment, treatments with two injection regimes, high and low intensity, and high and low daily frequency, were used. Oxygen analyzer was introduced into the tank to evaluate the gas concentration evolution along the fermentation.

Historical phenology records have indicated that advances in key developmental stages such as budburst, flowering and veraison are linked to increasing temperature caused by climate change. Using phenological models the timing of grapevine development in response to temperature can be characterized and projected in response to future climate scenarios.
We explore the development and use of grapevine phenological models and highlight several applications of models to characterize the timing of key stages of development of varieties, within and between regions, and the result of projections under different climate change scenarios.

Currently, grapevine is host to a large number of pathogenic agents, including 65 viruses, five viroids and eight phytoplasmas. Needless to say, these pathogens, especially viruses responsible for several ‘infectious degeneration’ or ‘decline’ cause great distress to wine makers and grape growers, let alone the large economic losses incurred by the wine industry. A recent addition to this wide repertoire of grapevine viruses is a new viral disease known as Red Blotch in viticulture parlance. Its causal organism, Grapevine red blotch associated virus (GRBaV), discovered in 2008 is a newly identified virus of grapevines and a putative member of a new genus within the family Geminiviridae.

We must state that two conditions above are only prevalent in the case when the processed grapes are full or over ripened, besides following the Tokaj wines preparation criterions (grape variety, soil, microclimate, vintage, etc.). These two conditions mentioned before were followed up only sensory based analysis up to now, altough the study of chemical idetified compounds which confirms these are obviuos.