Identifying New Zealand Sauvignon blanc terroirs

Nitrogen fertilization is an important practice to guarantee vineyards sustainability and performance over years, while ensuring berry quality. However, achieving a precise nitrogen fertilization to meet specific objectives of production is difficult. There is a lack of knowledge on the impact of nitrogen fertilizers (soil/foliar; organic/mineral) and different levels of fertilization on the interactions between carbon and nitrogen cycles within the vine. Crop models may be useful in that purpose because they can provide new insights of the effects of fertilization in carbon and nitrogen storage. The objective of this study is to build a model to simulate grapevine carbon and nitrogen content in vines to evaluate the impact of different fertilization strategies in vine growth and yield.

Phenolic compounds are important quality indicators in red wine. A large number of polyphenols play an important role in wine development, contributing to the colour and the sensory perception of the wines. Anthocyanins are the pigments responsible for the colour in young red wines while tannins are the principal contributors to the bitterness and the astringency of the wines. Wine polyphenols are considered more complex molecules than grape phenolics, due to the enormous number of chemical reactions which take place during the entire winemaking process and storage, forming more stable compounds.

Over the last decades, climate change and rising temperatures have impacted the wine industry. Wines from warm regions tend to have a higher pH and lower total acidity.

Pesticide residues in Austrian wines have so far been poorly documented. In 250 wines, 33 grape musts and 45 musts in fermentation, no limit values were exceeded, but in some cases high lev-els (>0.100 mg/l) of single residues were found, meaning that a reduction of these levels before bottling could make sense. In the course of this study, a white and a red wine were spiked with a mix of 23 pesticide residues from the group of fungicides (including botryticides), herbicides and insecticides. The influence of the following treatments on residue concentrations and volatile profiles were investigated: two activated charcoal products, a bentonite clay, two commer-cial mixed fining agents made of bentonite and charcoal, two yeast cell wall products, and a plant fiber-based novel filter additive. The results of this study show that all the agents tested reduced both residues and aromavolatile compounds in wine, with activated charcoal having the strongest effect and bentonite the weakest. The mixed agents and yeast wall products showed less aroma losses than charcoal products, but also lower residue reduction. Plant fibers showed good reduction of pesticides with moderate aroma damage, but these results need to be con-firmed under practical conditions.

Varietal Riesling aroma relies strongly on the formation and liberation of bound aroma compounds. Floral monoterpenes, green C6-alcohols, fruity C13-norisoprenoids and spicy volatile phenols are predominantly bound to disaccharides, which are produced and stored in the grape berry during berry maturation.