Acids form one of the four key components of wine, along with Alcohol, Tannins and Sugars (Sweetness). The nirvana for a winemaker is getting all these components in balance, the result, is usually a great wine!
I should start by saying that technically speaking, all wines are acidic, by which I mean they have a natural pH between 2.5 and 4.5 (a pH of 7 is neutral), but some grapes are naturally more acidic than others, and all lose acidity as they ripen.
Wines from cooler climates will often have naturally higher acidity as a result of less ripe fruit, whereas wines from very warm climates will often have less acidity as the fruit will ripen fully and quickly in the warmth and sunshine, reducing acidity but increasing sweetness. That said, natural acidity can be retained in warmer climates with higher altitude planting (increasing the wide diurnal range between night and day temperatures).
You may have heard people talk about a wine having “good acidity”, but what does it mean and why is it so important to wine?
Acid is hugely important to wine – without acids, colour would be dull, flavours muted, the ageing potential greatly reduced and the risk of harmful bacteria impacting the wine increased. Higher acid wines also make great food matches, the acidity cutting through the fattiness of the dishes.
A wine with high acidity will often be felt by a prickling sensation on the sides of the tongue (like when you suck a lemon sherbet!) and leads to a mouth-watering sensation. Naturally high acid grapes include Sauvignon Blanc, Riesling and Chenin Blanc, but it’s by no means the domain solely of white grapes, red grapes can also be high in acid: think Pinot Noir, Nebbiolo (ie Barolo) and one of the main ‘Rioja’ varieties: Tempranillo. Grapes that have a tendency to lower acidity include Gewürztraminer – although it should be noted, grapes grown in cooler climates can still maintain decent acidity, I tend to plump for the Alsace or New Zealand when drinking Gewürztraminer.
Coincidentally, ‘acidity’ impacts on the perception of ‘body’: so while a wine with good levels of acidity will feel lifted, fresh and vibrant in the mouth and provide balance to the wine, too much acid and the wine will just taste thin, tart and generally unpleasant. A ‘low acid’ wine on the other hand will feel flabby, muted and dull. It’s also worth noting that sweetness masks acidity so a sweet wine such as Sauternes will have very high acidity, which is balanced by sugars, creating a fresh yet sweet wine.
I will leave you with one final thought – You may come across the term ‘malolactic fermentation’ (‘MLF’ or ‘Malo’) from time to time, this is a secondary fermentation when malic acid is converted to lactic acid, which in layman’s terms means tart acid (like that from an apple) is converted to a softer, milkier acid (like that found….perhaps unsurprisingly in milk!). So a wine which undergoes malolactic fermentation will generally have a softer less sharp mouthfeel – In the case of white wines, while many Chardonnay’s will undergo MLF, most Sauvignon Blanc and Riesling wont, in order to retain the primary fresh fruity character of these grapes.
So there in a nutshell is ‘Acidity’. I hope you found the piece interesting and will be back tomorrow for the next instalment: ‘B is for Biodynamics’.