Vitamins in grape must: let’s lift a corner of the veil

The aim of this work was to study the trapping capacity of four polyaniline polymers towards phenolic compounds in wine-like model solutions. METHODS: The model wine solution was composed of 12% (v/v) and 4 g/L of tartaric acid adjusted to pH = 3.6. A series of centrifuge tubes (15 mL) were filled with 10 mL of model solution enriched with 50 mg/L of five phenolic compounds (i.e., Gallic acid, caffeic acid, (+)-catechin, (-)-epicatechin, and rutin), and treated with different doses of PANI polymer (i.e., 0, 2, 4 and 8 g/L). After the addition of the polymer, the samples were stirred using a platform shaker at room temperature (20 ºC) for 2, 8, 16 and 24 h. All treatments included three replications.

The observation of Earth by satellites has demonstrated the feasibility of establishing differences between plant species, from their spectral features. The reflectance spectrum of vine plants follows this trend, being possible to identify vineyards in satellite images, among other species.

In the current climatic context, with milder winters leading to earlier budburst in most wine regions, vines are exposed to the risk of spring frosts for a longer period. Depending on the year, frost can lead to yield losses of between 20 and 100 %, jeopardizing the economic survival of wine estates. In addition, by destroying young shoots, spring frosts can impact the following season’s production, by reducing the number of canes available for pruning, for example. Late pruning is one method to combat spring frosts.

Not only vintner’s decisions in the vineyard, but also winemaker’s choices of technology approaches in the cellar play a significant role in the final wine style and quality. Whereas traditional technologies within chosen terroir are quite well explored and thus somehow predictable, there is no proper knowledge available on possible outcomes in case of implementing novel, alternative winemaking strategies. To reveal their effects on wine aroma compounds and sensory characteristics, two alternative strategies
(cryoextraction or addition of whole grape berries during last stages of fermentation) were compared to classical Vipava valley winemaking approach as normally used for an autochthonous variety Zelen. After separate vinification and bottling, all the experimental wines were subjected to semiquantitative metabolic profiling of volatile compounds (VOCs) by means of GC/MS and were then also sensorialy evaluated by pre-trained panel.

A part, at least, of red wines fruity expression may be explained by perceptive interactions involving particularly various substituted ethyl esters and acetates present at concentration far below their olfactory threshold, specifically thanks to synergistic effects. Wine sensory perception is directly linked to the stimulation of the taster at the level of olfactory epithelium by volatiles. These compounds are liberated from the matrix to the atmosphere, and will then be smelt. From a physico-chemical point of view, these volatiles ability to be released may be evaluated by their partition coefficients, which correspond to the volatile concentration ratio between the liquid and gas phase. Our goal is, through these coefficients determination, to assess if volatile matrix composition is able to impact the volatility of some compounds, and then explain sensory perception, i.eto evaluate what is called the pre-sensorial level impact.