Last year I embarked on the Wine and Spirit Education Trust (WSET) Diploma, generously supported in my studies by my employer, Majestic Wine. Only ten employees are able to join the ranks of Diploma students every year, so to determine who makes the grade, we sit an entrance exam. The question I had answered was along the lines of ‘Wine is made from grapes, but seldom tastes of grapes. Explain this using examples.’ Not quite verbatim, but words to that effect.
It’s an interesting question, because of all the fruit-based alcohols, wine almost never resembles the fruit it comes from; only muscat ever comes close to having a grapey aroma, and often only then because in fortified form it has not undergone full fermentation. I scribbled out close to three pages of explanation over the allotted hour, and a month later I was delighted to find I had made the cut. (93 out of 100, it turns out, was the highest score anyone from Majestic has achieved on their entry exam)
I had an advantage over some of my fellow students with the same question, because most wine shop staff focus their education, unsurprisingly, on wine. I was a bartender before I was a wine merchant (or in Majestic’s case, a retail warehouse sales manager who is well trained in the properties of his stock), and one involved in the competition circuit to boot. I’d had more than a passing interest in flavour for quite some time, and I pretty much did a giddy dance when I saw the question.
Lots of factors affect the taste of wine. Some are in the vineyard, some are on the vine. Many are in the winery, and many are in the bottle, long after it has departed. Think of wine as a living thing, shaped by its environment and upbringing, as all living things are.
Without reproducing my answer in full, there are a few key factors in understanding why wine is not simply fermented grape juice. (although yes, technically, it is exactly fermented grape juice)
The chief cause is the process of fermentation itself, and how this reacts with natural esters in the grapes. Yeast converts sugar into alcohol and carbon dioxide. Alcohol has no flavour of its own, but it likes to bind itself to whatever esters are present and in this way it acts as a flavour enhancer. It’s one of the reasons a higher alcohol Gin will taste more robust than one at a lower strength. Grapes contain a lot of different esters and enzymes that are found in other plant material, and these differ depending on the grape variety. Riesling, for example, contains a terpene called trimethyl-dihydro-naphthalene which can result in an aroma likened – positively – to petrol, though sometimes referred to as paraffin or beeswax, as some people don’t react well to the idea of petrol in their wine. If you see a tasting note with TDN, this is what it’s referring to.
Climate plays a role, too. Cooler climates tend towards higher acidity and in particular, malic acid. Malic acid is the same as found in granny smith apples, and you’ll notice a distinct green apple character in AOC Chablis, for instance. In warmer climates, the fruit ripens more, and you’ll notice (along with higher alcohols) riper fruit characteristics. Chardonnay in Chablis may well show green apple and citrus fruit, along with white flower, but its counterpart in Sonoma will show stone fruit and maybe even tropical fruit. Same grape, possibly genetically the same clone, different flavour profile due to the growing conditions.
The type of yeast, too, can have an effect. Some ‘aromatic’ yeasts can add a tropical fruit character to the wine, and this is particularly noticeable in the (generally) inexpensive white wines they are used to make. Bargain bucket Loire wines can have a strangely artificial tropical aroma which is the result of these yeasts. Similarly, wines which have undergone carbonic maceration often display a bubblegum and confected fruit aroma. Personally, I dislike the aroma and it put me off Beaujolais for a long time, until I discovered some which did not use the method. I still groan when I catch a whiff of it in a cheap Languedoc Carignan or similar, I realise it makes fruity wines with lower tannin, but they’re not for me.
Coming back to acid, some white wines, and virtually all red wines, will undergo a further change called malolactic fermentation. By this process, harsher malic acid is converted into softer lactic acid. This adds a creamy character and a buttery note wines and lowers the perceptible acidity, making them more mellow. Why do some chardonnays have a buttery character? It’s malolactic fermentation.
There can be other yeasts at play, too. Sherry is a great example – definitely no trace of grapey aromas in a Fino. You make a neutral dry wine and then fortify it just enough to feed flor yeasts, which grow on top and protect the wine below from oxygen. They add a flavour of their own to the wine, a bready (yes, yeasty) bite. Likewise, secondary fermentation in Champagne with yeast trapped in a sealed bottle, the process of yeast autolysis (dead yeast cells breaking down) adds a brioche or even marmite characteristic. If you keep a dirty winery, or are lazy, or in France you call it part of the terroir, the bacteria brettanomyces (or brett for short) may infect your barrels and add its own funky character to the wine. Earthy, some call it, farmyard, others. Spoiled, say some. While it doesn’t do anything harmful to the wine per se, it certainly shifts the focus from fruit to savoury.
And what, speaking of sherry, about oxygen? It can ruin the fresh fruity aroma of a Sauvignon Blanc in the long run, (though in the very immediate term it ‘releases’ the aromas and helps carry the flavours) but in the case of, say, an Oloroso sherry it plays a vital role. Oxidative aromas in a wine can present a nutty, caramel character in a wine. A little bit of oxygen in the aging of non-fortified wines can be a good thing too, if you want some of that in your wine.
Let’s not forget oak, either. Oak aging allows some oxidative aging, for sure; wood may be watertight, but it’s not completely airtight. Mostly, but not completely. Over time, the wood expands as the air around it warms up, and contracts as it cools down. Even in a temperature controlled cellar, you’ll have some interaction of the liquid within with the wood. Seasoned wood contains more than just wood, it contains organic compounds, even fungal compounds, from its time before it was shaped into a barrel. These interact with the wine. The charring (toasting) of the inside of the barrel adds flavours. The oak itself adds vanillin, and if it is oak from America it had a coconut character as well. The same thing happens when aging bourbon, or malt whisky.
And then there’s the bottle. Glass is inert, yes, but the wine within is not. Sealed under cork there will be tiny interaction with oxygen over time, changing the wine in subtle ways. Pinot Noir goes from bright red fruits to savoury mushroom over time, and for some this is the apex of its development. Sauvignon Blanc becomes less gooseberry and tropical, more vegetal and asparagus; some love it, some loathe it. Champagne often becomes more oxidised, honeyed and richer. Under a screwcap with too perfect a seal the wine will become reductive (when there is lack of oxygen) and you may find an aroma of rotten eggs – this, thankfully, will dissipate in time, or if you’re clever you can drop a copper penny in, and the copper instantly reacts with the compounds to restore the wine. The dreaded trichloroanisole (TCA), or cork-taint, will reduce the wine to the aroma and flavour of wet cardboard, which is nothing like grapes at all, and from which there is no recovery.
All this barely scratches the surface, but it’s utterly fascinating when you think of what goes into making a wine, and why they taste as they do. Think about it next time you pop the cork, or snap the cap.