Terroir e DOC: riflessi produttivi e commercial

Barrel fermentation and barrel-ageing of wine are commonly utilised practices in premium wine production. The wine aroma compounds related to barrel contact are varied and can enhance a range of wine aromas and flavours, such as ‘struck flint’, ‘caramel’, ‘red berry’, ‘toasty’ and ‘nutty’, as well as conventional oaky characters such as ‘vanilla’, ‘spice’, ‘smoky’ and ‘coconut’. A survey of commercially produced premium Shiraz, Cabernet Sauvignon, Pinot Noir and Chardonnay wines was conducted, assessing the prevalence of compounds that have been proposed as barrel-ageing markers¹ including oak lactones, volatile phenols, furanones, aldehydes, thiazoles2,3, phenylmethanethiol⁴ and 2-furylmethanethiol.⁵

To obtain a quality wine, it is necessary to collect grapes in an optimal state of maturation, so the control of the ripening process is fundamental for the viticulturist.

Late season dehydration, bunch stem necrosis, sugar accumulation disorder and sunburn are various types of berry shrivel occurring in vineyards. The incidence of these types of shrivel, and the degree to which it occur are influenced by various factors in the vineyard. These factors include the presence of pests and diseases in the vineyard, genetic traits expressed in certain cultivars, as
well as climatic and environmental factors. The occurrence of berry shrivel in the vineyard could negatively impact the quality and quantity of the fruit produced.

Tannins are very important for grape and wine quality, since they participate in several organoleptic wine characteristics such as astringency perception, bitterness, and the colour stability. The compositions in tannins in grapes and wines differs between seeds and skins. Tannin seeds contain a higher concentration of tannins than skin and has been associated with a coarse and more tannic notes in wines, by contrast, tannin skin are related to a greater softness in the wines.

Tannins are a heterogenous class of polymeric phenolics found in grapes, oak barrels and wine. In red wine tannins are primarily responsible for astringency, though they also have an important role in reacting with and stabilizing pigments. There are numerous sub-classes of tannins found in wine but they all share structural heterogeneity within each sub-class, with varied polymer composition, configuration and length.

Numerous methodologies exist for the quantification of tannins, however, protein precipitation using bovine serum albumin has proved itself useful due to its strong correlation to the sensory perception of astringency and the basic instruments required for the method. Though the method can yield valuable insights into tannin composition, it cannot be automated easily and necessitates well-trained personnel.