What constitutes wine? Part 1 – Sweetness and acidity

To talk confidently about wine we need to define its structural components. So what constitutes wine? Here we discuss two aspects: sweetness and acidity

We all know some of the best conversations start in front of a glass of wine. But is it possible to successfully talk about wine? By that I mean, describe a wine and and confidently discuss its qualities and characteristics. Perhaps the first step is to ask what constitutes wine? 

However, such questions reveal wine’s slippery nature. Our tastes and the pleasure allotted by wine are deeply intertwined with subjectivity. Still, I do think it’s possible to talk about wine. We just need the right tools – these are:

1. To define the characteristics of wine: what constitutes wine?
2. To agree on a common vocabulary 

Let’s first grasp the dimensions that characterizes the most intriguing beverage on earth (if you are reading this blog you agree with me on what that is!). On a very broad level there are two main things that define wine:

• A set of structural components (sweetness, acidity, alcohol, tannins, body) that makes up a wine’s “architecture”
• The flavours that adorn the wine’s underlying structure

Components of wine and vocabulary

In this and my upcoming article of the knowledge section of Wine and Other Stories,  I will go through the structural components, examining their origin and effect on wine. I will answer the question: what constitutes wine? In another article, I will focus on wine flavours.

A note about vocabulary. Learning to properly “read” a wine can appear a daunting and almost intimidating endeavour. Especially when you read an expert description like the one that follows:

Significant and weighty body and saucy but racy acidity stabilises the wine nicely with the architecturally solid and ripe tannins

I wouldn’t encourage such a buzzwordy description. The ultimate aim of wine tasting notes is to communicate the magic summoned by a wine. Not to impress people. Nevertheless, every discipline requires its own language. So it’s important to agree on a common set of words, whose meaning is shared (at least it should be) among wine lovers. By describing what constitutes wine, I will try to give you a common vocabulary to talk about wine and its characteristics. My terminology is inspired by the WSET Syllabus (since I studied wine with them), but I will try to offer other alternative words or expressions where possible. 

Sweetness

Among the structural components defining what constitutes wine, sweetness is probably the easiest to recognise. We all experience sweetness in our life (I, probably more than I should. I have an incurable sweet tooth).  But why do wines contain varying levels of sweetness?

During fermentation a number of interesting things happen, the main one being that yeasts convert sugars found in the grapes into alcohol. A wine is said to be dry if the winemaker allows the yeasts to convert all of the sugar into alcohol. Most wines are dry. Unsurprisingly, sweet wines still have sugar in them. Below are the different techniques used to produce sweet wines (see Everything you need to know about Sweet Wines for more details on the subject):

• Stopping fermentation before all the sugar is converted into alcohol; the result will be a wine containing “residual sugar”. Port wines are made this way
• Starting with a grape must which is so sweet that the yeasts struggle to convert all of it and eventually give up – this can be achieved in a number of different ways: passito wines (Amarone della Valpolicella), botrytized wines (Sauternes, Tokaji), passerillage/late harvest wines (Spätlese and Auslese wines), ice wines
• Adding a sweet component to the wine (however this does not normally occur in fine winemaking)

Dry and bone-dry

In the wine world dry generally means that there is no detectable sugar – this is not the same as saying there is no sugar at all. Small doses of sugar can still be present to boost a wine’s palatableness. For example, several mass-produced New World chardonnays contain some sugar to make them more mellow and pleasant. Usually, dry wines can have up to 10g/L of residual sugar (the equivalent of 0.2–0.3% of sugar).

You might have heard a wine described as being bone dry. This expression is used where the wine tastes “drier than dry”. Normally this translates into a residual sugar of just a few grams per litre as opposed to 10g/L as above. Anyway for practical reasons, “dry” and “bone dry” are more or less the same.

Sugary stuff: sweet, off-dry, medium-dry, medium-sweet

Generally, a wine is referred to as sweet when sugar is its prominent feature. In technical terms, wine featuring more than 80-90g/L of sugar would be considered sweet. There are wines falling between the two extremes (dry and sweet) and these have a specific terminology.

In off-dry wines there is a barely noticeable touch of sugar. Often gewurztraminer and some German rieslings fall into this category. The words medium-dry and medium-sweet are used to describe wines where the sugar presence is distinctive, but not enough to be the major feature – or, to put it in a different way, wines which are sweet but not sweet enough to be paired with a dessert.

It’s curious to note that there is no universally accepted rules dictating how to apply the shared terminology for sweetness in wines. A famous exception is Champagne where the terms extra brut, brut, sec, semi-sec, etc. are tightly regulated and must be applied only if the sparkling features certain levels of sugar.

Interaction with other structural components

Sweetness (like any other structural wine component) affects other wine constituents. Acidity and sweetness mask each other. As a consequence, when the acidity in a wine is soaring, a bit of sugar can help balance out its structure – and it won’t be noticed by most drinkers. This happens in some German Riesling, Loire Vouvray and Brut Champagne. Sweetness can also affect body. A high quantity of sugar will enhance the body of a wine, resulting in a more weighty and enriched viscosity on the palate.

Acidity

If you asked a neophyte what constitutes wine, acidity would hardly be among the first answers. Acidity is probably the most undervalued and overlooked structural component of a wine.

When high, acidity boosts liveliness, freshness and crispness. It makes your mouth water and quenches at the same time giving a sense of focus and precision to the flavours. A wine that displays a high acidity can be defined as lively, fresh, bright, firm, zippy, crispy, racy, and angular.

On the other hand, a lack of acidity makes the wine taste flabby, shapeless and dull. In sweet wines, low acidity results in cloying and overly sugary drinks. A wine that is low in acidity can be described as soft, round, fat, stale, flabby, heavy (the last three have negative connotations).

The importance of acidity

Acidity is particularly important when pairing wine with food. Virtually all food-friendly wines have high acidity. The latter makes you want to have a bite of food, and a sip of wine again and again, supporting both elements of the pairing.

Acidity has another important impact: it allows the wine to live longer. Acting as a natural preservative (like tannins), acidity helps balance fruit aromas and preserves structure even when the fruitiness begins to fade with age.

Different types of acids

Wine contains different acids. The three main types of acids in wine are: tartaric (dominant in terms of composition), malic (this tart acid is also found in green apples) and lactic (converted from malic acid in a process called malolactic fermentation). Other acids (citric and others) are present, but in very limited quantities. All of these acids are present in liquid form and are completely odourless and aromaless. 

There is another kind of acidity which is important in determining the nature of wine: volatile acidity (VA). This is mainly caused by the presence of acetic acid. VA is formed during or after fermentation; it has a gaseous state and, unlike the aforementioned liquid acids, has a specific aroma. If VA is present in a small amount, it can contribute to the aromatic profile of a wine. When VA is too high, it adds unpleasant flavours of vinegar and nail polish remover and is considered a fault in the wine.

What affects acidity?

The extent of acidity in a wine is a combination of three main factors: climate, grape variety and winemaking decisions. As I explained here, wines from cool regions tend to display higher acidity. In warm and hot wine regions the acidity of the grapes may be so low that winemakers artificially add acids during or after fermentation (when permitted by local laws). 

Some grape varieties inherently have a high acidity – cabernet sauvignon, nebbiolo, riesling, sauvignon blanc. Others tend to have a low acidity. For example, gewurztraminer, viognier, dolcetto, grenache.

As grapes ripen, the levels of sugar and tannins in the berries increase, while the acidity falls. The key to attaining a balanced wine is to pick the berries at the right time, where the ripeness of all three (sugar, acidity, polyphenols) is optimal. Of course, compromises have to be made. The winemaker can influence the resulting acidity of the wine by picking berries at different times in the ripening process. By picking early,  the acidity of the wine will be higher. If the winemaker decides to pick later, the wine will feature a lower acidity, but have higher levels of sugar and tannins.

Merlot is a perfect example to show how harvest time can be crucial. When vinified according to the “international style” (mostly in warm New World regions), merlot is picked quite late in the season. The resulting wines display ripe or overripe black fruit, high level of alcohol and a soft acidity.

But there is another style of Merlot, mostly present in the Right Bank of Bordeaux. Here the grapes are picked much earlier. The wines produced are crunchy with succulent red fruit, more balanced in alcohol and with a higher acidity. Same grape, very different wines!

Detecting acidity in wine

How do we perceive acidity as a taste in the mouth? The answer is simple from a conceptual standpoint, but there are some caveats to be aware of.  Acidity makes your mouth water – that’s the most important effect to bear in mind when thinking about this taste. Acidity can be described as sourness, zestiness or a sensation that gives your taste buds simultaneous tingles and freshness. This sensation is usually more evident on the side of your tongue (even though the classical “tongue map”, where specific areas of the tongue are more sensitive to certain tastes, has been dismissed by the scientific community).

Alcohol and acidity can sometimes be confused (I’ve done this myself many times…) because they both cause a similar “burning” sensation. The way to tell one from another is the mouth-watering effect: if the latter is there, you are tasting a highly acidic wine.

A final note regarding acidity is about its quality. Not all high acidity is the same – this component is not one-dimensional. This aspect has not been much discussed, and our vocabulary is vague and imprecise in this regard. But I personally think it’s important to distinguish two dimensions of acidity:

• a harsh acidity: the tasting equivalent of a metal spoon scratching on a porcelain surface – an awful high-pitched sound; In this case, you will find adjectives (mostly implying a negative connotation) such as harsh, hard, tart, jagged
• a crystalline round high acidity: a pleasant and melodic violin solo – equally high-pitched but harmonious and limpid. A more pleasant terminology will address this type of acidity: crisp, zippy, racy, piercing, mouthwatering, steely, firm.

Final thoughts and what to expect next

I hope this article has made sweetness and acidity in wine less obscure to you. In my next article, I will continue my discussion on what constitutes wine, addressing the other three major components: alcohol, tannins and body. 

Now it’s time to practice what you’ve learnt so far! Next time you savour wine, try to ask yourself a few questions: is your wine dry? What about its acidity? Is it high or low? And how does it feel in the mouth? Between one sip and another, let me know in the comment section your thoughts, or contact me directly if you have any questions.