A brief explanation of some of the terms you might hear mentioned on TV wine shows or read in weekend wine columns.
Acidity gives wine its tartness and makes it taste sharp and crisp. You can easily detect acidity in a wine, it makes your mouth feel watery. A wine without enough acidity feels flat. As a wine ages, the acidity level drops, which is why simple cheap wines that are more than a year old can feel flabby and dull.
Acidity becomes lower as the grape ripens on the vine, so it is important the grape is picked when that vine has the right sugar and acidity balance. Grapes have different levels of natural acidity, and this is further altered by the climate they are grown in. High acidity reduces the perception of sweetness which is why cool climate whites often feel bone dry and thirst quenching.
Almost all wines are blended. Even a Sauvignon Blanc from one New Zealand winery is the product of blending a lot of tanks together. But blending different grapes together is a different thing and particular for some wines like Bordeaux, Rioja or Rhone reds. When this is traditional, it is usually that the blend of grapes creates a style better than a single grape. Each grape is used by the winemaker to fill in the gaps that the other ones in the blend cannot achieve; such as colour, texture or flavour dimension. This is usually done after fermentation but before ageing.
A form of rot. It occurs on grapes typically in damp humid conditions. Affected grapes will taste musty when made into wine. Therefore is it usual that the vineyard will try to treat vines to avoid it or would aim to select out bunches during harvest that are affected, a costly process. There is a special type of rot that is beneficial for wine “noble rot” – see below.
Carbon dioxide is a natural by-product of fermentation. If not released it will be captured and dissolved into the wine, making a sparkling wine. Such as bottle fermented Champagne method wines. It can also be used in small quantities at bottling to add a little zip into the wines. Typically that is used in aromatic whites and can be felt by a light prickle on the tongue.
Used when making red wine to take the colour and flavour from the red grape skins during fermentation. The techniques vary according to the type of grape. With thin skinned, delicate grapes, like Pinot Noir is typical to use manual “punch down” which involves a large rod pushing down the grapes from the top of the tank to mix in with the wine. For more tannic grapes like Cabernet Sauvignon more vigorous methods are used like “pump overs” which involves taking off juice at the bottom of the vat and pumping it over the wine. Whichever technique is used the winemaker has to take care to only extract the best part of the tannins in the skins and pips or bitterness will come through. And as the alcohol gets higher, during the progress of fermentation, extraction of those elements are more likely.
This is what happens to grape juice to turn it into wine. The ancient method relied on natural yeasts that exist in the environment to convert the sugars into alcohol. Some modern wines are still made that way. But there are also artificially made yeasts that are most commonly used today. Neither is the better method, but they produce different results. Some argue flavours of natural yeasts are more complex.
Beaujolais wines rely on this particular type of fermentation to get their soft and fruity styles of wine. It is when in the absence of air the whole grapes start to ferment inside themselves using the yeasts within their grape cells, eventually bursting and fermenting naturally. For the style of the resulting wine see carbonic maceration.
Lees Stirring/contact (“sur lie”)
Lees are dead yeast cells that settle after fermentation. They look brown and sludgy. Ignoring the fact that they are ugly, they do contain a wonder of nutrients and are a natural protector against oxygen, which can spoil wine. Winemakers can choose to remove the lees is they want a lean bodied style wine. If they use the lees, especially stirring it over time, this increases the body and adds a sense of biscuit richness to the wine.
There are several different acids within a grape. Malic acid is the type that tastes like a green apple and can be sharp if present in too high a quantity.
You’ll hear many a wine geek saying “I get a hint of malo in this wine”. It is a method of winemaking that can gives whites a creamy, slightly yoghurt-y note that softens out the palate. The process is a second type of fermentation that happens later in the wine’s life. Friendly bacteria convert one type of acid in the wine from “malic” (apple) to “lactic” (milky) flavoured. This is especially useful in wines with high acidity like Chablis. It doesn’t work well for aromatic grapes like Sauvignon where it would dull the aromatics.
This is a method used in red wine making where microscopic bubbles of oxygen are pumped into a wine while it is in early stages of ageing. That air then allows a tiny bit of oxidation that impacts the tannins to soften them a bit. It is very helpful for wines that naturally have high tannins.
This is a special type of rot that favours particular climatic conditions. Microscopic fungi pierce the grape, allowing the water in the grape to shrivel so the grapes raisin and concentrates its sweetness. When made into wine the high sugar grapes have an almond oil richness and produce some of the best dessert wines in the world.
There are two main types of oak used widely in winemaking; French and American. French oak has tighter grains that deliver more spicy flavours such as cloves, black pepper, cocoa and cinnamon. American oak has a sweeter profile and therefore gives flavours such as coconut, vanilla or chocolate.
In some European countries they use Slavonian oak, typically in large casks which give less flavour to the wine.
If new oak is used, it will give the wine a lot of flavour and tannin, so often winemakers will choose different ages of barrel, some with many years of previous use. That then makes sure the oak flavours don’t overpower the wine.
There are lots of artificial oak ageing methods available. Big staves of oak can be put in tanks, oak chips that are placed in while the wine ferments, or even oak powder. Chips can taste a bit more like Nesquik chocolate powder, with an obvious sweetness.
When you get an apple and it starts to go brown, that is oxidation. The same would happen to wine if it is left open to air and eventually it turns to vinegar. Leave a glass of wine for a few days and the aroma and flavour will go from fruit to sour and balsamic. That is when the wine has fully oxidised and the impact is negative.
As a wine ages in bottle or barrel oxidation will take place. The tiny gaps within the grain of oak will let in air, slowly. This has a “good” oxidative impact that starts to break down tannins to become gentler, and to change the flavours of fruit bringing out more “tertiary” characters which are the complex third type of flavours in wine; leather, tobacco for reds and more honey’d caramelised notes in whites. In a bottle this happens much more slowly because the wine is sealed and less exposed to oxygen.
Natural chemical compounds found in wine; usually in grapes stems, skins, pulp and pips. Part of this group of compounds are tannins. Phenols can give more texture, body or colour to a wine. Red wines have longer contact with their skins and so typically are more phenolic than whites. But some white grapes have thicker skins and thereby have more phenolic content than other white grapes; these grapes can have more weight and texture e.g. Muscat or Pinot Grigio.
Compounds that give a herbaceous character to the wine, in reds like Merlot this can be green bell pepper or with whites like Sauvignon the grassy notes.
Reduction is the opposite of oxidation. It is what happens when there is not enough oxygen allowed to reach the wine. Then compounds called sulphides lock in giving the wine a burnt matchstick aroma, or worse rotten eggs. A mild bit of reduction makes the wine feel “shy” because it closes down aromas and flavours. A clever trick is to put a copper coin into the glass of wine which reverses the reaction in these cases. Or swirling the glass around a lot to let oxygen in.
Winemakers should keep a close eye on their wine to avoid this. They do bottle wine with a bit of sulphur dioxide gas, especially with screw caps to avoid oxygen getting in. If too much is used the wine easily becomes “reduced”.
The amount of sugar in a wine, you sense this on the tip of the tongue. Dry wines typically have less than 3 grams a litre left in the wine. In some wines it is part of the natural grape sugar that wasn’t converted into alcohol. A wine maker can choose to stop fermentation before all the sugar is used leaving that sweetness in the style. A wine can have sugar added at the end, sometimes this is natural grape juice or it can be a factory made grape concentrate; typically in cheaper wines.
Tannin is the textural drying feel you get on your teeth, especially when tasting big reds; like tea leaves. It comes from the skin and pips of grapes, and also from the oak it can be aged in. There is “good” and “bad” tannin. If the winemaker is skilled he can extract the tannin whilst making reds to take off the tannins that will add structure and texture in a good way. But if he works the grapes too hard the bitter part of the pips will come through. Equally and unripe grape will have bitter tannin because they need to be fully mature for the pip to go from green to brown. Different grapes have varying types of tannin, Pinot Noir can be low and thin, whilst Nebbiolo or Sangiovese are high, and thick textured.
Some grapes varieties are high in terpene character. This can give an exotic floral note to the wine that becomes more kerosene with age. Grapes that typically display this are Gewurztraminer, Muscat or Riesling.
Certain grape varieties are high in these compounds which give a pungent aromatic character. A good example is Sauvignon Blanc which is known for its black currant or gooseberry.
Naturally vigorous vines want to put all their energy into producing lots of leaves and shoots rather than into the grapes. Therefore the skill of the viticulturalist is to tame those vines to minimise vegetation. If he doesn’t then the grapes won’t fully maximise their potential.
This is the type of acidity that gives wine a slight vinegary aroma. It is present in low doses in most wines but if it gets too high it is a dominant feature that makes the wine feel unclean. It is caused by a type of bacteria that converts some of the wine into acetic acid (vinegar), a clean winery can avoid the presence of that bacteria