A Breakdown from Translucent, to Green, to Yellow, to Brown
Freddie Mercury drank Saint Saphorin from Switzerland. Keira Knightley drinks Belluard’s “Les Alpes”. David Beckham drinks Meursault.
We all love white wine. Vinho Verde, Albariño, Palomino, Pinot Gris, Pinot Blanc... just a small handful of white grape varieties that are all named after their colour. There are around 700 white grape varieties used for the production of white wine in the world.
In other words, it is a vinous labyrinth.
Every grape variety has a different hue. Some are green, some are white, some are orange and some are pink. The colour pigmentation is restricted to its skin; the interior of every white grape berry is clear, so if you press your thumb and forefinger together and squeeze it, the skin will break and clear juice that looks like water will rush out. This means that darker-skinned varieties don’t necessarily give you a darker white wine. 99% of black grape varieties have white flesh too, so it is possible to make white wines from black grapes. Blanc de Noirs Champagne is the most well-known example of this, where white Champagne is often made from Pinot Noir and Pinot Meunier, black grape varieties.
Natural Taste: Aromatics vs. Non-Aromatics
All of those 700 white grapes taste different, naturally. Not just as wine, but also if you were to eat the berries.
From emerging scientific research, we know that nature gives us things called terpenes; monoterpenes, and sesquiterpenes. These contribute to the creation of a giant flavour alphabet. They give characteristics such as perfume-like smells, floral smells and pepper notes. They all have specific names, and they all result in different profiles. Linalool (a monoterpene) for example, contributes to the smell of things like lavender and basil, and you find it in grapes such as Gewürztraminer.
These are aromatic grape varieties. Some grapes simply have far less of them, such as Chardonnay, which will never taste floral. These are known as non-aromatic white grapes. It is common for winemakers of these varieties to play a little more with winemaking techniques such as extended ageing on the lees, or reductive techniques (more on this later), to add greater depth of flavour.
Science tells us that we cannot taste the soil type in the wine, but we disagree. This is both sensory and philosophical, but there are notions that soil type particularly can affect the texture in the mouth of certain wines. Certain soil types and grape varieties are vinous matches made in heaven, such as Chardonnay on limestone, or Riesling on slate.
Viticultural practices can also affect the taste; if you farm to produce a lot of fruit, or use a lot of irrigation, often the fruit will become more dilute and less flavoursome. Meanwhile, if yields are lower, this can result in really concentrated fruit flavour. The direction the vineyard is planted (its exposure) also determines the concentration of fruit flavour, as does the general climate; more sun, more sugar and thus fruitier flavours.
The decision of when to pick is often considered the most difficult decision in the entire year of producing wine. Not only does sugar accumulate in the berry over time (contributing to higher alcohol), but the skins also change colour. After véraison (the term for when green grapes turn either “white” or “black”), the berries will gradually become darker; in the case of white wine, more golden. This means if you harvest your Chardonnay earlier, it is likely it will be paler, whereas a darker harvest would likely result in more golden liquid.
Acid retention in grapes also varies immensely during the ripening season, so acid levels need to be checked. This can be done with a device or it can be done by simply tasting a berry every day. Timing is everything; in some cases just a few days’ delay can add an entire degree of alcohol.
What goes on in the Cellar?
There are various ways of turning white grapes into juice. Often, they are pressed directly with the popular whole bunch method, to receive a fresh and crisp white wine. The woody part of the bunch acts like juice funnels and the juice flows directly out, and the skins get separated. If the goal is to extract a little more flavour from the skins, the grapes may be foot stomped, or the juice may be left to macerate together with the juice from anywhere between a couple of hours to a few days. If left any longer, the white wine enters "skin maceration/orange wine" territory.
Stainless steel, plastic, fibreglass, cement, concrete, glass, oak, chestnut... There are dozens of options for your wine’s home. Steel, for example, does not allow the wine to have contact with oxygen, and so generally produces fruit-forward or stony wines, whereas the porosity of oak allows wine and oxygen to correspond. Old oak will impart no flavour on the wine, whereas new oak will give some flavour (or a lot). Different species of oak also give different flavours; American oak trees naturally taste sweeter, like coconut, whereas French oak trees are more subtle and quite literally “woody”.
Fermentation temperature can drastically alter the taste of the resulting white wine. Cooler ferments tend to preserve fruitier aromatics, and can also create esters like isoamyl acetate, which tastes like pear drop sweets.
Without yeasts, we would not have wine. These fungi turn grape juice into wine. The choice between deciding to rely on the wild yeasts in your vineyard and cellar to do the job, or to add cultured yeasts, will have anything from a very small to an enormous effect on the wine.
Cultured yeasts, that come in bags from laboratories, are reliable and “tick all the boxes” for winemaking. They ensure fast, dry fermentations, minimising any risk, and the winemaker can even add all sorts of yeasts that produce specific aromas.
However, they eliminate the element of mystery. As soon as a human being chooses a yeast strain, Mother Nature’s role in the fermentation is taken away from her. What’s more, it is argued that wild fermentations, that occur spontaneously without any yeast additions, produce the most complex wines, due to the interaction that occurs between several yeast strains. It is a conversation of sorts; a synergy. We feel it’s a little like imagining a bar packed full of hundreds of people of every ethnicity, all partying together, versus a bar with just one person, or ten people all selected specifically for a certain characteristic of theirs.
Click to hear natural yeasts happily fermenting some Riesling at Christoph Hoch's winery
Grape juice undergoes many natural chemical reactions before it becomes wine. When you think of acid, you might imagine a green apple. This is malic acid, and it is also present in all white wine at the start of a wine’s life. If left to its own devices, a tribe of bacteria in the wine will convert this acid into lactic acid (the same acid present in milk or cheese), which softens the wine.
Whether to stop this process or not is a stylistic decision made by the winemaker and can be done by the addition of SO2 or filtering.
Some wines may naturally have such low pH levels that the malolactic conversion may never occur, particularly with grape varieties such as Riesling or Albariño.
The taste of... Oxygen?
Yes, that very same oxygen that keeps us alive. O2 oxidises phenolic compounds in wine and “must” (must is grape juice, seeds, skins, etc). This is either desired or avoided by the winemaker, depending on the type of wine they wish to make. One of the side effects of oxidation is known as “browning”, which quite literally does what it says on the tin.
Brown Juice? Not Brown Wine
Much like it does to your bananas, oxygen turns juice brown. For a long time, winemakers would protect their juice from browning (also known as “the oxidation of the must”) as they didn’t want a brown wine for obvious reasons. However, it turns out that this browning can in fact go away; from a brown juice you can get a pale-yellow white wine. The chemical reactions taking place between enzymes and molecules form large molecules that contain the brown colour. These molecules eventually “fall out” of the wine - meaning literally to the bottom of the tank. What’s more; it is believed that the wine is now chemically more protected from oxidation occurring in the future.
Once the juice has turned into wine, the wine produces no more carbon dioxide (which the wine produces naturally during fermentation) and thus is not self-protecting itself from oxygen. This is when oxygen can play a real role in determining the flavour characteristics of the final wine.
Oxidation, when managed correctly, can lead to some great wines, such as sherries, the vin jaune wines of the Jura, the famed Lopez de Heredia Viña Tondonia Reserva Blanco, and the thrilling range of "Smiley" wines crafted by Ryan Mostert and Samantha Suddons.
It leads to a loss of the upfront, fruity characteristics, and instead introduces aromas of beeswax, nuts and honey can appear. Sometimes, a surface yeast called "flor" is encouraged, which adds a salty tang.
However, if not monitored, it can also become problematic; certain bacteria and fungi can multiply quickly in the presence of oxygen. This could eventually turn the wine into vinegar. So, by allowing the wine to have contact with oxygen, the winemaker walks the tightrope of what can create a brilliant wine, and what can ruin a wine.
"Reductive" White Winemaking
If you make a wine reductively, you are actively avoiding oxygen. There are many ways of doing this.
Sulphur dioxide is added to the majority of wine produced in the world. It exists in powder and liquid forms, and can be chemically created or mined. It prevents oxidation by binding to compounds and microorganisms in wine. As Abe Schoener of the Scholium Project says, “it puts these parts of the wine to sleep.”
There is a growing movement towards creating wines with very little levels of sulphur, or none at all. It is still possible to create reductive styles with no sulphur, by...
Like in whisky, the angels take their share. To get rid of unwanted oxygen in winemaking, it is really quite simple: keep the barrel full. This means that any “headspace” in the barrel (which equals oxygen) will be extinguished, which equals no oxygen. Typically this is done every couple of weeks, with “topping wine.” This topping wine represents such a minute volume of final wine that it is likely to be a blend of anything that did not initially fit into the barrels.
Using the Lees
When a wine is put away in a barrel to “sleep” over winter, it isn’t really sleeping. The liquid is in constant conversation with its surroundings, and this includes the “stuff” that gathers at the bottom of the barrel. This “stuff” is known as the lees, and is predominantly yeast cells.
If the aim is a fruity, light white wine, these lees will be removed almost right away, but if the goal is to develop complex lots of other flavours, they are left to interact with the wine.
When Lees is More, and when Lees is NOT More
These yeasts also affect the flavour of wine in the form of hints of croissants or freshly baked dough. If moved around or stirred in the barrel, they increase the concentration of mannoproteins, which can contribute to creaminess, texture, and richness. If not stirred, this creates more of a reductive environment; less of the softness and more of the direct fruit remains.
However, this is where we enter the tightrope walking scenario again. Lees, on their own, favour the production of sulphur compounds. These can create great wines and they can create undrinkable wines. Many of the world’s finest white wines play with this notion; if you poke your nose into a glass of fine white Burgundy and you suddenly think of lighting a match, this is the result of these sulphur compounds.
However, there are good and bad sulphur compounds, and the non-matchstick ones can be a disaster: think rotten eggs, garbage, old cabbage and even sewers. Once the really evil ones arrive on the scene, they’re incredibly difficult to get out.
Bottling & Setting the Snooze Button
Bottling and ageing decisions impact your wine. Some wines are made to be bottled early and enjoyed early. Others are put on snooze in the cellar or in the bottle for many years.
In the End, it's all about Balance
There are many tightropes to be crossed when making white wine and many decisions to be made to complete the puzzle of the wine in question. Ultimately, balance is crucial, and this starts in winter with pruning decisions, and ends with bottling or ageing. Then - when it comes to flavour - that’s where the fun lies for us human beings.