Identification of green, aggressive and hard character of wines by a chemo-sensory directed methodology

In partnership with a Bordeaux property wanting to improve the quality of its second wine, the effects of two factors, American oak barrels and mannoproteins were studied. Their impact on the attractiveness and sweetness of wines were characterized during two successive vintages (2012 and 2013). Vinification took place with a homogeneous batch of Cabernet Sauvignon. The wine was then divided up into various groups of five barrels of French and American oak, new or reused. Analyses of volatile and non-volatile wood compounds were undertaken at four months and eight months of wood ageing, by LC-MS and GC-MS.

Limited information is available on grape wall-derived polymeric structure/composition and how this changes during fermentation. Commercial winemaking operations use enzymes that target the polysaccharide-rich polymers of the cell walls of grape tissues to clarify musts and extract pigments during the fermentations. In this study we have assessed changes in polysaccharide composition/ turnover throughout the winemaking process by applying recently developed cell wall profiling approaches to both wine and pomace polysaccharides. The methods included gas chromatography for monosaccharide composition (GC-MS), infra-red (IR) spectroscopy and comprehensive microarray polymer profiling
(CoMPP) using cell wall probes.

Adrenaline (epinephrine) belongs to catecholamine class. It is a neurotransmitter and both a hormone which is released by the sympathetic nervous system and adrenal medulla in response to a range of stresses in order to regulate blood pressure, cardiac stimulation, relaxation of smooth muscles and other physiological processes. Adrenaline exhibits an effective antioxidant capacity (1). However, adrenalin is capable to auto-oxidation and in this case it generates toxic reactive oxygen intermediates and adrenochrome. Under in vitro conditions, auto-oxidation of adrenaline occurs in an alkaline medium (2).

C-Glucosidic ellagitannins, which are the main polyphenolic compounds in oak heartwood, are extracted by wine during aging in oak barrels. Although such maturing of alcoholic beverages in oak barrels is a multi-centennial practice, very little is known on the impact of these ellagitannins on the organoleptic properties of red wine. The objectives of the present investigation were (i) to isolate oak ellagitannins and to hemisynthesize some made-in-wine flavano-ellagitannins, such as acutissimin A; (ii) to analyse their concentration ranges depending on the cultivar area and (iii) to evaluate their sensory impact on the basis of their human threshold concentrations and dose/response relationships in different types of solutions.

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.