Wine Tannins Explained (Everything you need to know)

Hello and welcome to Leonorose Wine. In today's episode we are covering everything you need to know about tannins. Now whether you're a casual wine drinker or you're a sommelier that's been in the industry for decades, you've probably or definitely heard the word tannins. But do you know what they actually are? I mean we know they kind of make your mouth dry and some wines have more than others, but what are tannins on a scientific level? I want you to think back to that last glass of red wine you had. If it was something like Cabernet Sauvignon or Sangiovese, you probably noticed that kind of dry slightly chalky feeling that you get in the back of your mouth like on your gums. That's tannins. That feeling, that sensation, that is tannins at work. So when we talk about like what makes up a glass of wine, what is the composition of wine itself, we primarily normally think about aromas and flavors. But also we have the body, the structure of the wine itself, things like alcohol and acidity and sugar content. Tannins fit into that second group. They're part of the structure. I like to think about it as the architectural framework that these more delicate elements can then reside within. Okay really quick before we dive in, I just want to introduce myself. My name is Liana and I have a master's degree in sustainable viticulture and enology. Viticulture being the science of grape growing, vineyard management, and enology being winemaking. I basically study all the fun technical nerdy science stuff that helps us produce the wine that we love to drink. Be sure to subscribe to this channel and follow me on social at lianaroswine. From a scientific standpoint, tannins are polyphenolic compounds. They come from plants and within grapes they're part of the vine's natural defense system. They help protect the fruit from things like uv radiation, pests, and diseases. Now when we talk about tannins being polyphenols, I think it's helpful to know what that actually means on the chemical level. Polyphenols are a large family of plant compounds. Chemically they're built around phenol structures which are carbon-based rings with hydroxyl groups attached. Now poly means many, so polyphenol just means that there are many units of phenols put together. And as I said earlier, tannins are just one specific type of polyphenol. What makes them different from other polyphenols are their size and complexity. Tannins are larger molecules with multiple phenolic rings and that allows them to bind strongly to proteins. That protein binding is key. This is why tannins interact with your saliva and gives you that weird dry grippy feeling. It's actually the tannins interacting with the protein in your saliva. So basically we could say that all tannins are polyphenols, but not all polyphenols are tannins. In wine the two main sources of tannins are from the grapes themselves as well as any wood that's used during the winemaking process. Let's start with the grape tannins. So grape tannins can be found within the grapes themselves whether in the skin or the seeds and then also in the stems of the grape bunches. During fermentation and maceration these tannins are extracted into the wine as the juice stays in contact with the solid parts of the grape. But tannins can also come from wood. During winemaking and aging producers might use wood additions like wood chips or wood granules. They also traditionally use barrels. Wood is used in winemaking for a couple of reasons. I'll do a whole episode on this in the future, but generally we think of wood as being used one as adding tannins, two as maybe introducing some new aromas or flavors. This is not due to tannins, that's a separate separate function, but it's also a benefit of using wood. And then as well as that we have micro oxygenation that aids in the aging process and I'll go into that more later. So as the wine interacts with the wood over time, tannins are slowly extracted adding both some structure and texture to the wine. To make things even more interesting and not at all complicated, especially different types of tannins. And these different tannins create different sensory experiences when you drink wine. Under the broad umbrella of tannins we usually talk about three main groups. We have hydrolyzable tannins, condensed tannins, and complex tannins. These groups differ in their chemical structure, where they come from, and how they behave in wine. Which is why it's so important for us to understand these differences in terms of If we go one level deeper, hydrolyzable tannins are actually broken down into two subcategories and I gotta check how to say this. Gallotannins and elegantannins. These distinctions become especially important once we start talking about barrels, aging, and how tannins evolve over time. Okay, it's getting scientific in here. I feel like we all just need to take like one breath in, breath out. We got this? Okay, here we go. The most important group to start with is condensed tannins. These are the tannins that come from the grapes themselves, be it the skins, the seeds, or the stems. Sensory-wise, condensed tannins are what we usually think about when we're talking about a wine being grippy, drying, or astringent. They play a huge role in structure, mouthfeel, and aging potential. Hydrolyzable tannins are a little bit different. These tannins mostly come from wood, especially oak that's used in winemaking. Their chemical structure allows them to easily break down over time, which is where this name hydrolyzable comes from. As we said, hydrolyzable tannins can be broken down into two subtypes, the gallotannins and the elegantannins, which are common in oak. Elegantannins are especially important because they interact with the oxygen and other wine compounds, helping stabilize the color and also soften the texture as the wine ages. Then there are the complex tannins, and these actually form later during winemaking and aging when tannins react with other compounds in the wine, such as anthocyanins. These reactions change both the structure and the sensory profile of the tannins, making them feel rounder, smoother, and more integrated over time. So while all tannins contribute to a wine's texture and structure, their origin and their chemistry impact exactly how harsh or smooth they are, as well as how age-worthy the wine feels. All right, exhale. We did it. Now let's bring this all together. With all of these types of tannins and their origins, there's a lot of decisions for both winemakers and vineyard managers to think about. When we talk about terroir or a terroir, it is a combination of climate, soil, and landscape, as well as the human decisions that help shape a wine to be what it is, both in taste and feeling and in experience. So the goal isn't to force a wine into a specific style, but rather to decide how to best express what's naturally there. In the vineyard, one of the first considerations is grape variety. Different varieties naturally have different tannin levels and structures. For example, Pinot Noir has a relatively thin skin as compared to something like Cabernet Sauvignon. This is one of the reasons why something like Cabernet Sauvignon results in a much more tannic wine than the Pinot Noir. Environmental factors also play a major role. Climate in particular has a big influence on tannin production. Warmer climates tend to produce riper tannins, which feel softer and rounder, whereas colder climates produce less ripe tannins that are greener or more sharp and aggressive. Sun exposure is also a factor. We see that increased sunlight encourages thicker skin production as it's a natural protective response to the increase in UV radiation. Since tannins are generally concentrated in the skins, more sun exposure leads to a higher tannin potential in the resulting wine. Water availability is another important variable. Under conditions of low rainfall or moderate water stress, grape varieties tend to be smaller and contain less water. This increases the skin-to-pulp ratio, which can lead to wines with more concentrated tannins. And if not properly managed, this can result in tannins and a wine that feels intense or unbalanced. Finally, harvest plays a huge role in tannin character. Earlier harvest leads to, again, greener and more aggressive tannins that feel sharper and stringent, whereas grapes that ripen longer on the vine tend to mature and polymerize, leading to softer and more integrated tannins. Okay, now let's head back to the winery. Once the grapes arrive, the winemakers have a lot of decisions to make. One of the first choices that winemakers have is whether or not they want to keep the stems or remove them. Most of the time, the winemakers will choose to remove the stems from the grape clusters before fermentation. However, sometimes they leave them in and do something that is called whole cluster fermentation. Because, as we know, stems contain tannins, keeping them in contact with the must increases tannin extraction. But it's a decision that requires careful balance, as it can create a wine that has too much tannin extraction that is, in the end, undesirable. When grapes are de-stemmed, which is most of the time, tannins are extracted mainly from the skins and the seeds. One of the biggest factors in controlling tannin extraction is skin contact, which is basically how long the juice stays in contact with the skins and seeds of the grape. The longer that they are in contact, generally, the more tannin extraction occurs. Winemakers can also influence tannin extraction through temperature. Higher fermentation temperatures increase the rate of tannin extraction. There's also techniques that are used to mix the must during fermentation. These are punch downs, where you punch, literally punch down the must and mix in, reincorporate the drying skins that have floated to the top, and you push them down, mix them around, as you can see in the video. And then there's also pump overs, where you pump from the bottom of the must and dump it on top, and it circulates again. The idea here is that you are keeping the juice in contact with these skins and seeds. Now, sometimes, and again, it just depends, sometimes winemakers will add enzymes that actually help break down the cell walls and speed up extraction. Once the wine is finally done fermenting, we need to separate the solids from the liquid wine, and that's done through pressing. But the harder you squeeze to get the juice out, the more tannins you're going to pull. And oftentimes, if you over extract, you can create something that is very bitter and harsh, and you don't want to drink that. So yet another decision that winemakers need to choose. It's also important to note that winemaking additions and techniques are regulated differently across the world. What's permitted in somewhere like California may or may not be permitted in France or Italy, so it just, it depends where you are. We have our wine, finally, but what about the wood? One of the most important aspects of barrel aging actually isn't even the tannins themselves, but rather the small amount of oxygen that passes through the barrel into the wine. When tannins interact with oxygen, a process occurs called polymerization. Polymerization is when smaller tannin molecules link with one another to create larger complex tannin. This process helps to sharp, aggressive tannins into a more desirable, smoother, rounded tannin experience. Larger tannin molecules are less likely to bind to the protein in your saliva, which is what causes that grippy feeling. So by having larger polymerized tannins, that experience actually becomes less drying. That's why older wines often feel smoother and softer than young wines. This process doesn't stop when the wine leaves the barrel. Actually, this keeps happening once the wine is in the bottle. This is the whole idea around having your wine bottle aged, keeping them for 10, 20 years. And finally, I have to mention that tannins influence a wine's ability to be aged. Tannins protect with the color of the wine as well as provide microbial stability. So a higher tannin wine can theoretically age a lot longer than one that is low in tannins. So there you go, all the tannin science you could ever desire. You are definitely going to be the most popular person in that tasting room or at the dinner party because people definitely love when you talk about wine. Okay, with all that being said, what does that actually mean for the fun part, for drinking and tasting great wine? Well, first of all, tannin level is definitely a personal preference. Some people love wines with high tannins, others don't. Having a better understanding of what tannins are and how to describe them gives you a huge advantage when choosing wines at a local shop or talking to a sommelier. Tannin level is also key when it comes to wine and food pairings. Tannins, as we talked about, dry your mouth out. So eat something fatty, a steak, something rich with butter. It's great with salt. It can be very overpowering for more delicate foods, so I wouldn't recommend pairing it with something a little more subtle. If you're still watching, I'm gonna assume you're a bit of a wine nerd like me. So here's a little homework to take your tannin knowledge to the next level. Grab a cup of strongly brewed black tea and take a sip. Notice the drying in your gums, in your mouth, and add a little bit of milk to that. Taste it again. That experience, the softening, the roundness, that is the experience of tannins binding with proteins. Thank you so much for joining me today to talk about wine. If you'd like to keep learning about the science behind wine from vineyard to cellar, be sure to subscribe to this channel. I'll be sharing videos on everything from vine anatomy, fermentation, sensory science, aromatics. If there's something that you'd like me to talk about next, be sure to comment below and maybe your idea will be the next video. Thanks for watching and be sure to subscribe and follow for more wine science information. Cheers!