Enological characterization of mold resistant varieties grown in the Trentino Alpine Region

In Chile there is a dry farming area known as a traditional wine region, where varieties brought by the Spanish conquerors still persist. These varieties, in general, are cultivated under traditional systems, with low use of technical and economic resources, and low profitability for their grapes and wines. In this region, as in other wine grape growing areas, climatic conditions have changed significantly in recent decades. In particular, the occurrence of spring frosts, when bud break has already begun, have generated significant losses for these growers.

Bentonite fining is commonly used in oenology to remove all or parts of white wine proteins, which are known to be involved in haze formation. This fining is effective, but has disadvantages: it is not selective, thus molecules responsible for aroma are also removed, it causes substantial volume losses, and finally it generates wastes. Over the last decades, the knowledge of wine proteins has increased: they have been identified, their structures are known, some of them have been crystallized.

The potassium (K) supply characteristics and clay mineralogies of a population of Western Cape soils were investigated to determine their potential effects on vine K uptake and wine quality. The total K contents of granite-, shale- and sandstone-derived soils varied, averaging 33.7, 26.1 and 4.5 cmol(+)/kg, respectively. Corresponding M NH4Cl exchangeable soil K levels were: 0.172, 0.042 and 0.035 cmol/kg.

Red grape pomace, a waste from wine production, can be valorised by extracting polyphenols, high-added value compounds used in cosmetics or oenology. For use at an industrial level, using green extraction techniques, pomace need to be stored before being processed. The aim of this study is to test various storage conditions in order to maintain high level of polyphenols over 180 days, while keeping storage cost economically interesting. In a first step, different storage conditions (ambient temperature or cooled (4°C) temperature, anaerobic (saturation with N2) or aerobic conditions, and addition of sulphur dioxide (SO2)) were compared on small samples (1 kg) packed in plastic pockets. The quality of storage was assessed by following the optical density of the pomace extract at 280 nm (DO 280 expressed as mg/l eq gallic acid), which is an indication of the amount of remaining extractable polyphenols.

AIM: Three Oenococcus oeni strains previously isolated from spontaneous malolactic fermentation were characterized for their surface properties. Planktonic and sessile cells were investigated for aroma compounds production and the expression of genes involved in citrate and malate metabolism (citE and mleA, respectively), glycoside-hydrolase (dsrO), fructansucrase (levO), rhamnosyl-transferase (wobB), glycosyltransferase (wobO).