University of
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Nerd Stuff
This section is titled as such because I know my fellow wine nerds can understand a lot about a wine from the information on this list.
However, if you do not quite understand what some of these terms mean, and want to join the ranks of wine nerdom, then you’re in the right place.
This list is going to mostly be in chronological order from harvest to bottle, and will probably continue to grow, so scroll down to learn just what each term actually means. It will be a long section, so buckle up, and I hope you like flow charts.
Harvest
The timing of when to actually harvest the grapes is probably the most important decision a producer has to make, but that’s for a different section. There are two main ways to harvest the grapes:
- By hand.
- By machine.
Hand harvesting
This is when a producer gets a team together and physically goes out to the vineyard and clips each cluster to bring it back to the winery.
Pros: Each cluster can be inspected at the moment of harvest which can help remove grape clusters that may be rotten or damaged. It also means each cluster is more carefully harvested which preserves the grapes instead of bruise or break them before they get to the winery.
Cons: It can be VERY expensive to hire the labor required for harvest. The process is much slower as well, and timing matters to try and beat the heat of the sun which can affect acidity.
Machine harvesting
There are some ingenius machines out there that look like tall tractors, and they basically straddle a row of vines while driving up and down and knocking off the grapes into a container.
Pros: Cheaper in the long run, since a huge amount of acreage can be covered by one person. It is also much quicker and can be utilized with shorter notice if a storm pops up in the forecast.
Cons: There’s no way to inspect the clusters while they’re being harvested, making it more likely lower quality grapes will make it into the wine. The grapes get damaged during the process which can affect the flavors before they get to the winery.
Why does hand harvesting matter?
Seeing this on a label can tell you a few things about the wine and its producer. First off, it probably means it’s a smaller, artisanal producer since hand-harvesting becomes almost impossible at a large scale. A small winery is usually going to be able to producer higher quality wine since attention to detail and focus on fewer products is greater.
It also means that the producer was willing to invest the time and money in preserving the quality of the grapes that are to be used for the wine, and if this is the case, it means they probably applied that care to the rest of the operation as well.
Pre-fermentation
Once the grapes are harvested, they are quickly brought inside the winery where a few things can happen before the fermentation process begins.
Cooling
Lower temperatures will preserve the grapes aromatics and acidity, which is why harvest usually takes place at night or in the morning. To enhance that, the grapes are sometimes put into cold storage for a day or two before pressing.
Pressing
How the grapes are pressed is determined by the desired final product. The classic barrel looking press, like the one my grandfather used, is really only for making personal wine. Anything larger than that, even the smallest commercial producers, are going to use two main types of machines to press the grapes:
- Pneumatic press
- A crusher/destemmer
Pneumatic press
These can come in all different sizes, but they are basically going to look like giant propane tanks. The inside contains an inflatable balloon type thing that is going to press the grapes against the inside of the tank to release the juice into a container below.
The main point of these is to gently press out the juice with as little skin contact as possible since the juice is immediately pouring out of the tank away from the skins, stems, and seeds. The pressure of the balloon can be set very precisely, which means it will not break the seeds either, which would add too much tannin and other flavors. This means that the juice does not pick up flavors, colors, or tannin from the skins, stems, or seeds, which makes this a good option for white wine, rosé, or very light red wine.
Crusher/destemmer
This machine is going to be used to achieve basically the opposite of the pneumatic press and give the juice the ability to extract flavors from the skins and seeds. Although technically two separate tasks, crushing and destemming are often done at the same time, so this ends up being one big machine that is SUPER annoying to clean.
Full clusters are dumped into the top of the machine, where they go through a corkscrew-like portion of the machine, which aggressively beats and agitates the grape clusters to both separate the berries from the stems and to break open (crush) the skins to release the juice. The stems are removed and discarded, but the juice, skins, and seeds all fall out together as a thick mixture into a container below. From here, the producer can decide how long they want the juice to be in contact with the mixture.
Cold soaking
After the grapes are crushed with their seeds and skins, they can start to pick up flavor, color, and tannin depending on how much time is spent in the mixture. The reason this is a COLD soak, is to make sure the juice does not start fermenting. This is important because tannin is more easily extracted at higher temperatures. On top of that, the alcohol produced by the fermentation with further enhance the extraction of tannin. Therefore, by keeping the mixture cold, the juice can pull out more color and flavor without becoming too astringent. This is the same reason tea is best steeped at set times, otherwise it becomes too tannic.
Fermentation
This of course produces the good stuff. Alcohol. The process can be as basic as forgetting about some fruit in a trash can, to the super complicated, precise, and nerve-racking period in a winery. So here are a few factors that contribute to the final product.
Vessel
A number of vessels can be used for this process, but for more, check out the vessels 101 section.
Yeast
The star of the show, and could absolutely be its own section, but here’s the short version: Yeast are microscopic fungi that are responsible for converting grape juice into wine. More than that though, the fermentation process unleashes new aromatic compounds that were not detectable in the grapes beforehand. Each strain of yeast is going to impart different aromas and flavors during the process, but there are two main categories to understand:
Ambient yeast
This means that the producer chose to let the wine ferment naturally with the yeast found on the grape skins, and in the air of the winery. This produces a pure representation of the grape’s terroir which can be much more complex but is very unreliable and unpredictable, sometimes resulting in a failed fermentation altogether.
Cultured yeast
This is yeast that was designed in a lab to meet specific requirements for different wines. A producer can use this type of yeast to achieve a desired result with much better reliability and accuracy. Of course, it comes at the cost of losing some of the wines natural character and can sometimes be less complex than ambient yeast.
Cap management
During fermentation, the yeast will not only turn sugar into alcohol, but release CO2 and heat. If the wine is being fermented together with the skins and seeds, the CO2 will push all of that (called the “cap”) to the top of the tank. The problem, is that this is where most the flavor and color is, so in order to get the most out of the fermentation process, the juice needs to be constantly mixed back in with the skins and seeds. This is done in two ways:
Pump-overs
Here, a hose is connected to the bottom nozzle of the tank, hooked up to a pump, and then the opening of the hose is placed at the top of the tank. The process pulls wine from the bottom of the tank and pours it over the solid cap floating at the top. This is beneficial because it mixes all the juice with the cap to extract as much flavor as possible, but it also aerates the wine which can pick up undesirable, reductive notes.
Punch-downs
This method is used to physically push down the cap at the top, usually with some metal pole with a flat bottom. This is a more aggressive way to mix the cap back in with the juice because the pressure from pushing it down can squeeze the skins and seeds, releasing more tannin. Therefore, it is generally used for thin-skinned varieties that need more extraction like Pinot Noir or Grenache than it would be for something like Cabernet Sauvignon, where it might be very easy to over-extract the tannins. It can be done by hand (and makes for a great workout) on smaller vessels, or by machine in large commercial tanks.
Chaptalization
The addition of sugar to the grape juice to increase alcohol percentage. This is typically done if the vintage did not ripen the grapes naturally enough to produce the desired level of alcohol. It can be a common practice but is illegal in many sub-regions except in rare occasions where the producer can request the ability to chaptalize.
Acidification
Sort of the opposite of chaptalization. This is where a producer will add acidity to the wine, typically citric acid, if it’s determined that the grapes natural acidity is too low. This can also be illegal in certain areas, or it is acceptable to either chaptalize or acidify, but not both in the same year.
Aging
Vessels
See vessels 101
Malolactic fermentation
Although technically this is a fermentation, it is in the aging section because it takes place after the primary alcoholic fermentation. This is a choice of the wine maker and can be encouraged or stopped by temperature or filtering the wine. The three main effects of malolactic fermentation, (often referred to as MLF or MF) are:
- Reducing perceived acidity.
- Stabilization.
- Changes to flavor and texture.
You are probably familiar with this term from its use in Chardonnay, where it can turn a light, crisp wine into a richer, rounder wine with notes of butter and cream. What you may not know is that almost all red wines go through MLF, but the result is less obvious because it’s more for the texture than flavor.
MLF
This is a bacterial fermentation, as opposed to the alcoholic fermentation which is achieved through yeast (a fungus). If the winemaker chooses to let the wine go through MLF, it will affect the wine in the three ways mentioned above.
Reducing acidity
The fermentation converts malic acid (like the acidity in apples) to lactic acid (the acidity in milk) which decreases the perception of acidity in the wine and will move from crisp and tart like and apple, to soft and round like in milk. I say “perception” because the actual acidity remains, it just does not feel as tart.
Stabilization
The process of MLF stabilizes the wine by removing what would be nutrients for other bacteria to feed on can cause spoilage down the road.
Changes to flavor and texture
These actually depend on the variety itself, so results will vary wine to wine. But in general, the most common flavors associated with MLF are butter and cream. These can be very obvious in a Chardonnay, so it’s up to the winemaker to make sure it adds complexity instead of dominating the wine.
The texture will move from tart and linear, to a softer and rounder mouthfeel. This can transform a wine like Chardonnay into a completely different style, or just smooth out the overall texture of a wine like in reds.
Sur-Lie
You’ll often see this on a label, or that the wine was “aged on the lees” if a wine (typically white) has spent part of the aging process in contact with the yeast cells left over from fermentation. Usually, these are racked off (the wine is removed from the vessel with the solid yeast cells remaining at the bottom and discarded.) However, if a winemaker chooses to age the wine “sur-lie” this means that the yeast cells will not be removed and will continue to add flavor into the wine. These flavors are typically things like:
- Bread dough
- Cheese rind
- Beer
- Yeast (obviously)
- Toast
During the aging process, the yeast settles at the bottom of the vessel, so it needs to be mixed back in with the wine to maximize the affect. This process is called batonnage and involves someone in the winery stirring every barrel of wine for a few minutes a day.
Racking
This is a process to essentially clarify a wine as it spends time aging an maturing in the winery. As mentioned above, any solids or sediment start to slowly fall and collect at the bottom of a vessel.
So when a winery “racks” the wine, it is simply transferring the wine from one vessel to another while discarding the solids at the bottom. This can be done as many times as the producer feels is necessary to get the desired clarification.
Pre-bottling
These are actions that can technically be done at any time at the winery, but usually happen close to bottling.
Fining
This is a process where some type of protein is added to the wine to help clarify it further and remove things like solids and tannins. Most common proteins are:
- Egg whites
- Casein (derived from milk)
- Gelatin
- Clay
- Charcoal
- Fish bladder (small amounts)
Not all wines will go through this process though. The producer will typically skip this step if the goal is to produce a more natural product, to stay away from potential allergens, or the wine may simply not need it (too much can strip a wine of its character).
It can be used with precision though to clarify wines and reduce over-astringent tannins. It is a very common practice, and to be honest, I’ve never come across a wine that used fish bladder, so don’t worry.
Vegan wines?
You might think it’s ridiculous to see a wine say that it’s vegan on the label, but a quick glance at some of the proteins above should help make sense of that.
As mentioned, a lot of wines are not fined, so if that step is skipped, or they use a fining agent that is not derived from an animal (clay, charcoal, and some vegetable-based agents) then the wine is technically vegan.
This can be helpful for allergens as well, which are starting to appear more on labels.
How does it work?
Tannins bind to proteins in a tank the same way they do when you pair a Cabernet Sauvignon with a fatty rib-eye steak. The tannins and the proteins have opposite charges, which attracts and binds them. From there, they sink to the bottom of the tank and can be removed. The concept is the same in the pairing as the tannins bind to the protein of the steak and get washed away when you swallow, refreshing your palate for the next bite.
Filtering
Another process that is not only optional but can be controversial. In this case the wine is filtered through some type of machine to further clarify and reduce solids. This can be beneficial to make sure wines are not cloudy as a final product, but many argue that it takes too much away from the nature of the wine.
It’s important to note that good producers are going to be very careful with these steps and not only use the correct techniques but do so only if it enhances the wine.
Lab Data
This will be a quick run-down on some lab terms you may come across with a deeper look at each in extra credit.
Brix
Pronounced “bricks” not “Brie.” This is a measurement for the sugar levels in grapes before harvest. The number rises as the grapes ripen and develop more sugar, which lets the producer know when to harvest.
pH
You’re probably familiar with this, but as a refresher, this is a scale measuring how acidic/basic a liquid is. The scale is from 0 to 14 with 7 being basically water. Wine typically falls within the 3 to 4.
TA (Total Acidity)
Just when you thought you were getting the hang of this wine thing, you find out that there not just one or two types of acids in your wine, but many. Total acidity is probably more important to the winemaker than it is to you, but in case you’re interested, the most important acids are:
- Tartaric
- Acetic
- Citric
- Malic
- Lactic
Each of these are going to play different roles in the wine, and are explained in extra credit.
Alcohol
I mean, you know this, it’s why you’re here. But just to add some value to this line, the alcohol produced during fermentation is called ethyl alcohol.
RS (Residual Sugar)
This refers to the amount of sugar that remains in the wine after fermentation. Much more on this in the extra credit section, for the most part this will be an indication of whether or not the wine is sweet. It is measured in terms of grams per liter, so 3 grams of sugar in a liter would give the wine 0.3% RS. Typically, anything at 0.3% or less will not be detectible, and is therefore a dry wine.
Brix
As grapes ripen, they start to lose acidity and gain sugars. The key to a good wine is catching a grape at the perfect intersection of acidity and sugar. The brix measurements help with this by giving the producer quantifiable data to go along with their instinct.
It can also help determine the final alcohol percentage of a wine before it’s made referred to as “potential alcohol”. By multiplying the brix by around 0.6, you can estimate how strong the wine would be if you were to harvest at that moment. For instance, if you get a read of 20 brix, those grapes have an alcohol potential of around 12%.
Usually, the sweet spot for white wines is from 20-24 brix, and 22-26 for reds. Although this will vary from region to region.
RS
Even if a wine has been fermented to “dry” it can still hold a tiny amount of sugar, but the key is whether or not you will be able to taste it. At such low rates, like anything below 0.3%, you will not be able to detect any sugar, so the wine will be considered dry.
Grape juice is going to contain a few different types of sugars, some of which cannot be converted into alcohol by yeast, and will therefore remain in the finished product no matter what. However, this type is usually not perceived by your palate anyway, so it would not add to the sweetness.
TA
As I mentioned before, this number is far more important to the winemaker to make decisions at the winery than it is for you to understand the wine. But here is a brief explanation of each.
Tartaric
This is probably the most important since it contributes to the mouthfeel of the wine as is fairly strong.
Acetic
Too much of this can cause the wine fault VA, or volatile acidity which is where the wine starts to smell like nail polish remover. At low levels, it can add complexity and give a balsamic vinegar quality to the wine.
Citric
This is the same acid found in citrus like lemons and limes. It’s not as powerful as some of the other acids but can contribute to the wine’s tartness.
Malic
A strong acid that is the same found in apples. It plays a big part in the perceived acidity of a wine and can be tempered by MF.
Lactic
The result of MF. This is the acid found in milk and will contribute to a much softer and rounder mouthfeel.
Conclusion
Put together, the process should look something like this for standard wines. There are any exceptions, but this should give you a general idea.
