Tannins can be scary. When overpowering, they can leave you feeling like Wiley Coyote after a dose of Acme alum. But when they are right, tannins can be intrinsic to red wine. They add a lot of flavor, mouthfeel, and overall quality. This article delves into the intricate world of tannin profiles found in grape seeds, stems, and skins, and how these variations can elevate your winemaking process. By understanding the unique characteristics of each tannin source, you can become a master weaver, skillfully blending your production techniques to get the results you want.

Tannins are the enigmatic polyphenolic compounds found in various plant tissues, including grape seeds, stems, and skins. They contribute to color, astringency, and mouthfeel, and in beer production, they can even influence haze formation and overall flavor profile. Despite their importance, the tannin profiles of grape seeds, stems, and skins often remain shrouded in mystery for home beer and winemakers. This article aims to lift the veil and reveal the distinct characteristics of these tannin sources and their implications.

1. The Bold and Bitter: Tannin Profiles in Grape Seeds:

Grape seeds are packed with tannins, primarily in the form of condensed tannins or proanthocyanidins. These tannins boast high molecular weight and strong astringency, making them the bold and bitter stars of the tannin world. Factors such as grape variety, ripeness, and maceration techniques can influence the extraction of seed tannins. While seed tannins can be more bitter and astringent than those found in grape skins, leading to a harsher mouthfeel, when harnessed correctly, they can contribute to the structure and aging potential of your wine. They also can lengthen your flavor experience. That sensation in the back of your throat from a dry red comes from seed tannins. Without it, your wine might "short" as in the flavor does not linger. Seed tannins get a bad rap but, they play an important role in your tannin profile.

2. The Subtle and Smooth: Tannin Profiles in Grape Stems:

Stems typically contain lower concentrations of tannins compared to seeds and skins. Stem tannins are primarily hydrolyzable tannins, composed of gallic acid or ellagic acid esterified with a sugar molecule. These tannins are the subtle and smooth counterparts to the bold seed tannins, with their lower molecular weight and less astringent nature. However, excessive stem contact during maceration can lead to the extraction of undesirable green or herbaceous flavors. Tread lightly with stem inclusion to achieve a balanced tannin profile. Don't remove the small pieces because subtle amounts can really improve the complexity of the nose and taste. The larger stems are a different story. As you are punching down your must cap, remove them as they surface.

3. The Versatile and Vibrant: Tannin Profiles in Grape Skins:

Grape skins contain both condensed and hydrolyzable tannins. Skin tannins are generally less astringent and bitter than seed tannins, contributing to a smoother mouthfeel. That silkiness you get from a tannic red comes from skin tannins. Factors such as grape variety, maceration techniques, and fermentation temperature can influence the extraction of skin tannins.

4. Tips

If you are making wine from fresh grapes, you might want to consider the size of the seeds, the juice to skin ratio and the innate characteristic of the varietal to determine how long you wait to press after fermentation. With grapes like Pinot Noir, the seeds are small, and the skins are thin but, Pinot is a light bodied wine so the tannin level will need to be controlled. Cabernet Sauvignon is more substantial in all aspects so you might want to consider pushing the envelope. Just taste it often and be ready to press. As the alcohol levels go up, tannin extraction accelerates because alcohol is quite a formidable solvent. As for the stems, instead of picking them clean, leave some in. It doesn’t have to be a lot but, just enough to add those additional characteristics.

Using pectic enzyme, also known as pectinase, will also assist in extracting more skin tannins. By breaking down the pectin, the enzyme helps to release more juice from the fruit, which, in turn, allows for better contact between the grape skins and the juice. 

On a side note, bitter tannins are often mistakenly blamed on waiting too long to press however, too much bitterness often comes from breaking the seed hulls while pressing. As the alcohol breaks them down, they get more fragile so try to filter most of the seeds out before pressing. Most will sink to the bottom of your fermenter anyway. After you drain your free flow wine, scoop out the skins into the press. Then pour out your fermenter through a stainless steel strainer. Though that bottom layer contains a lot of dead yeast cells, if you are adding them to your press on the top, most will be filtered out by the skins. 

When working with kits or juice, there are a few easy fixes available to you. You could try powdered tannins. They are a tannin extract that offer precise control over the tannin content in your wine, allowing you to fine-tune the flavor profile, mouthfeel, and aging potential with ease. By carefully selecting the type and quantity of powdered tannins to match your desired attributes, you can enhance the overall quality and complexity of your homemade wine with ease. Additionally, powdered tannins can be used to correct imbalances or deficiencies in the natural tannin content of your grapes.

You could also use fresh skins and dried seeds. Fresh grape skins are stored in freezers to maintain freshness. You can get them cold shipped and just add them to your primary fermentation bucket. Seeds are also available in varying weights and can easily be added to your batch. Both together will add substantial complexity to your kit or fresh juice wines. So if you don’t have a winery and cannot work from fresh grapes, you have options that can really improve your results.

 

5. Patience and Preservation:

If you are going to push your tannin levels, patience is required. High tannins mean longer aging. Tannins are hesitantly social compounds. They like to group together but it is a slow dance. Over time, they form chains and the longer they get, the more peasant they become. When tannins are short, you can taste the bitterness because they are small enough to get into those little crevices on your tongue. Once they coalesce, they are too big to register. That is when you can really enjoy them. At that stage, you get all the positives without the bitterness and astringency.

Tannins also help contribute to the stability of your wine as it ages. A tannic wine has a lot more aging potential. Old world Barolo winemaking techniques left the wine on the skins for 3 months. Many had to be aged for at least 10 years before they could be sold and then cellared for even longer before they were drinkable. While a few niche wineries still practice this technique, most have moved on because long term storage is cost prohibitive. That said, if you have a bold red with higher tannins, adequate sulfite levels and some patience, you could have a masterpiece on your hands if you have the self control to not drink it for at least a few years. 

6. Conclusion:

Mastering the art of tannin weaving by understanding the distinct tannin profiles in grape seeds, stems, and skins is essential for optimizing your home beer and winemaking techniques. By skillfully managing the extraction and inclusion of these tannin sources, you can create beverages with the perfect sensory attributes and overall quality. Further research and experimentation in small-scale production settings can help refine your techniques. So, go forth and weave your tannin tapestry with confidence and creativity!