Wine making

Extraction Defined

Posted by on April 19, 2013
Wine making / No Comments

‘Extraction’, is a term that has reportedly been used by Robert M. Parker Jr. 901 times in about 30,000 tasting notes, but what exactly does it mean, and what does it mean when a wine is overly-extracted?

Rémi Edange, assistant manager at Domaine de Chevalier, explained the dangers of over-extraction to Decanter Magazine in 2009 stating that:

‘When you have thick, hard skins like this, you do not want to pump over or pigeage too much because you could force out some hard tannins.’

Devising a maceration schedule is a lot more complicated than one might imagine. As Jonathan Multus explained to us last week at Château Teyssier: ‘After pin pointing the exact moment to harvest, the second critical point is having the ability to taste the juice and control the validity of the wine through creating a regime of wine making operations’. Maceration and pump over decisions will be dictated by the degree of physiological ripeness in the grape, measurements will be conducted, such as pH, total acidity, sugar, tannin and phenolic quantification, however none of these equate to a definite answer with regards to how vigorously, at what temperature and for what duration maceration or pump overs should be carried out, simply because there are too many variables involved. Increasing temperature will enhance the release of polyphenols as will increasing the addition of Sulphur dioxide. Consequently, the wine maker will also need to use their experience and expertise, as well as chemical analysis to make calculated decisions.

After crushing, involving the release of the juice, the yeast present on the skin will mix with the juice, and fermentation commences, this produces alcohol, which aids extraction of polyphenols (held in the skin- containing tannins and anthocyanins). Carbon dioxide is also produced, creating bubbles which become entrapped within the solid matter, forcing it to the surface, producing the ‘cap’ (chapeau in French). Cap management must then be carried out for two primary reasons; acetic bacteria present will turn the wine into vinegar should the cap not become submerged, and the floating cap of skins needs to be in contact with the liquid, in order for the flavour and colour to be released. The mixing of the cap process can be performed in a number of ways; human foot, manually punching-down using a pole (being careful not to slip into the tank and become asphyxiated by the carbon dioxide), the submerged cap process, mechanical pumping-over systems, délestage or rack and return (the clue is in the name), and various other methods. All techniques must be carefully controlled in order to not ‘over extract’. Figure 1: illustrates a cross section interpretation of a grape. Good tannins are located in the skins, juice and pulp, whereas bad tannins are found in the seeds and stalks, these bad tannins impart a bitter taste and harsh sensation. Hence, the real skill lies in managing the operations to achieve a balanced wine. Leading research oenologist Emile Peynaud explains that “Diverse flavours from acids, sugars, salts and phenolic substances … that blend into a form, a more or less harmonious volume which makes up structure. [These essential flavours] constitute the bricks and mortar of a wine, its framework, also sometimes described as its bone structure.”

The need to achieve sufficient extraction is also paramount, with certain wine critics highly praising the presence of intense fruit and body within the wine. Therefore wine makers might choose to adopt techniques that maximise extraction. The Oxford Wine Companion defines extraction as: “The sum of the non-volatile solids of a wine: the sugars, non-volatile acids, minerals, phenolics, glycerol, glycols and traces of other substances such as proteins, pectins and gums.” Essentially everything in the wine minus the liquid, which can be perceived as the wines personality.

In conclusion, a wine that gets classified as being ‘over extracted’, at worse will be displaying bitter and harsh tannins, and at best will be too in your face, having lost its harmony and finesse.

Fig 1: source