Acidity is one of the most important elements in wine. It gives wines their freshness. If a wine is too low in acid, it tastes flat and dull; if too high it tastes too tart and sour. The main acids in wine are tartaric and malic (from the grape juice) or lactic (converted from malic acid in most reds and many whites through a process called the malolactic fermentation).
Both tartaric and malic acids are nonvolatile. This means that they do not evaporate or boil off when the wine is heated. This compares with volatile acidity (VA), which represents acetic acid (vinegar). Acetic acid does boil off when heated. A VA of 0.03-0.06% is produced during fermentation as a byproduct of microbial metabolism and is considered a normal level. While higher levels are generally considered a spoilage product, some winemakers seek a low or barely detectible level to add to the perceived complexity of a wine.
Acid is detected most strongly at the sides of the tongue where it causes a sharp tingling sensation -try a swig of that fancy vinegar languishing in the cupboard that you never got around to using.
Tartaric and malic acids are produced by the grape as it develops. In warm climates, these acids are lost through the biochemical process of respiration. Grapes grown in warmer climates therefore have lower acidity than grapes grown in cooler climates - e.g. cool Chablis versus warm Napa Valley. The relative amounts of tartaric and malic acids also vary depending on the grape variety and on where the grapes are grown. For example, in Burgundy, the Chardonnay has a lower concentration of malic acid than the Chardonnay grown in the Napa Valley of California.
Note that sugar production is the complete opposite of acid production. The warmer the climate the higher the sugar content of the grapes. Sugar content of grape juice is expressed in percent (%) or ° Brix (e.g., 24 % sugar is equal to 24 ° Brix).
Dry table wines typically have 5-7 grammes of acidity per litre. This compares with over 10 grammes in the case of sweet wines as the acidity provides a counterpoint to the sweetness.
pH also plays an important role. If you recall your chemistry lessons, this is a measure of the acidity or basicity of an aqueous solution. Or in more technical terms the decimal logarithm of the reciprocal of the hydrogen ion activity, aH+, in a solution (thank you Wikipedia). Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline. Pure water has a pH very close to 7. Wine pH is generally in the range of 3-4; about 3.0 to 3.4 is desirable for white wines, while about 3.3 to 3.6 is best for reds. (Compare with 2.0 for lemon juice and 14.0 for liquid drain cleaner), pH units are logarithmic so that a pH of 3.0 is ten times more acidic than a pH of 4.0.
Tricks of the trade: winemakers can add a mix of calcium carbonate and calcium tartrate-malate to de-acidify wines in cooler climate regions where the grape acid levels have not fallen sufficiently; conversely in warmer areas where the acid levels have fallen too far they can be increased through the addition of tartaric acid in powder form.
Wine offer #5: a selection of fresh mineral laden whites with plentiful acidity to counter the Tokyo summer.
With the sultry Tokyo summer just around the corner this week we bring you a selection of fresh mineral laden whites with plentiful acidity to help quench your thirst.
White Bordeaux 2011, France: Jean-Michel Cazes, of Lynch-Bages, Ormes de Pez and other top estates, makes this classic Graves blend of Sauvignon Blanc and Semillon. Ripe passion fruit and tropical overtones with a hint of marzipan from a limited amount of exposure to new oak. On the palate it is really pithy and zippy, with a mass of orangy fruit and mouth-watering grapefruit acidity. Rich, juicy and well-balanced, this wine with its modest 12.5% alcohol is an absolute winner for summer drinking.
Marlborough Sauvignon Blanc 2011, Churton, New Zealand - Down on the floor of the Wairau valley there was so much Sauvignon Blanc made in 2011 that the locals dubbed it the 'Savelanche' vintage. But up on the ridge bwetween the Omaka and Waihopai valleys, where Churton have their vineyards the yields were kept under tight control. This is made from 10 different vineyard blocks, each fermented separately. The wines are aged for a minimum of 9 months on lees. This allows for slow settling and for the wines to slowly absorb the complex polysaccharides released through yeast autolysis. Relatively high total acidity of 7.3 grammes per litre coupled with a low pH level of 3.00 make for a taut refreshing Sauvignon Blanc that goes well with food.
Chablis du Colombier 2012, Vincent Mothe, Burgundy France - Dedication to producing wines that reflect the true terroir of Chablis has been a family tradition in the Mothe family for five generations. Located in Fontenay, the estate is comprised of forty-three hectares of vines mostly in the village of Chablis with other smallholdings in the Premier cru vineyards of Bougros and Fourchaumes. All wines are fermented entirely in stainless steel to capture the unique characteristics of great Chablis - crisp, well balanced and mineral rich.
Rheingau Riesling Kabinett 2010, Georg Muller, Germany - A far cry from the dismal sugar water with which Germany is oft associated, this wine has a bright lemon colour and fresh, fruity nose of apple, citrus and peach. This is a soft, elegant wine, nicely rounded with the typical underlying and refreshing acidity of the Riesling grape. It is fruity, delicate and harmonious. Serve at 10-12°C.
Sancerre Les Chasseignes 2012, Claude Riffault, Loire Valley, France - Domaine Claude Riffault is one of the shining stars of the Sancerre appellation. Sancerre, predominantly known for the production of world-class Sauvignon Blanc, is located in the eastern Loire Valley. Geographically and geologically, it is closer to Chablis (in Burgundy) than most of the rest of the Loire Valley. Made up primarily of broken limestone and fl int (called "silex") soils, this region produces white wines of amazing purity and cut, often with smoky aromas. This wine is 100% Sauvignon Blanc from limestone soils on hillsides. Hand harvested and fermented in stainless steel tanks to maintain the fruit and freshness of the wine. Produced from 30-40 year old vines.
Mix your own 3 bottle packs for 10,000, 6 bottle packs 18,000
No space to store your wine? Don't worry, 12 bottle cases come with three months free warehousing in our temperature controlled facilities in Shinagawa. Bottles can then be delivered from the warehouse for collection at wine bar Parabola.