Would you mind explaining a little to me about tannins. I really don’t know when I use them and when I shouldn’t. Same with oxidation. I’m having a terrible time trying to control it. Any advice??
Tannins and Oxidation
- Thread starter DaveB
- Start date
Help Support Winemaking Talk - Winemaking Forum:
Ohio Bob
Senior Member
Tannins act as an antioxidant to scavenge oxygen molecules. Oxygen is necessary for fermentation, as yeast needs oxygen to grow in population and be healthy. Wine however is different, oxygen is detrimental.
In primary fermentation, grape skins become sacrificial tannins. It’s common to add oak chips or shavings to the fermenter to supply sacrificial tannins. This leaves the skins to provide color, tannins, and other compounds that benefit the wine.
After fermentation is complete, potassium metabisulfite provides the antioxidant protection. It binds with oxygen molecules so the oxygen is not detrimental. Kmeta only lasts 3 months or so, so continued racking, and/or sulphite addition is necessary for continued protection against oxidation. Kmeta is also anti microbial so additional protection is given.
Tannins are often added during bulk aging to add structure, mouthfeel, and other benefits besides being an antioxidant.
Read up on the tannins available in the Scott fermentation handbook.
https://scottlab.com/content/files/documents/handbooks/scott labs 2024 winemaking handbook.pdf
Wow that’s informative. I was having trouble understanding this definitely makes it clearer. I think it’s time for me to learn more about this. Thank you!!
Oxidation; it is hard to make good tasting wine without metabisulphite (free SO2 ). Do you have the ability to measure SO2 ? As a start I would try this crop year and look at doubling the metabisulphite treatments as one choice. Head space is related to oxidation, another choice is to spend effort eliminating most ullage. My target anytime I rack is to have about 1.5 inch, 3 to 3.5 cm. Oxygen can be involved with any transfer, as a result I try to be quiescent using long racking canes that touch the bottom of a vessel. Industry will nitrogen flush or vacuum bottling headspace so I also use vacuum to do corking at -15 inch Hg. Conclusion we can always do better so look at your whole process.
Tannins; tannins are natural polyphenols. Polyphenols are a natural family of chemicals. Some give the nice red color in aronia (a super fruit) and the purple color in red grapes. The class of polyphenol called tannin is a polymer of catechin of variable length. There is a different flavor depending on polymer length. Plants produce tannin as a mechanism to resist insects/ predation. The flavor depends, therefore Scott sells a variety of clean tannins from several different plants. I have crab apples, if I describe the flavor early season / August is bitter (hard tannin), when fruit is ripe / September flavor is astringent (also called soft tannin) and pleasing. After frost the fruit is flavorless. In wine tannins have a similar flavor progression, therefore we speak of young aggressive red wines. I practice tasting fruit and even the skins of apple cultivars. Grape skins have soft tannin, seeds have hard tannins.
Chestnut tannin is a commercial soft tannin which I find in the store. A soft tannin / astringent flavor will magnify the flavor of acidity, tannin can be used to increase freshness of a fruity flavor. Testing flavor it doesn’t require a lot. A few grains picked with a tooth pick can improve the flavor of a glass of wine.
I put tannin in all wines. Sometimes I may add 2% aronia in a clear juice. I may steep 5 to 10% crab apple with a white grape juice to add soft tannins. I may run a mulberry with a teaspoon per gallon of grape tannin and then go to a club meeting and ask “can you guess what variety this is?” Tannin is magic, as a start I suggest get what the local store sells (or the Scott labs tannin kit) and take a toothpick to see how the flavor of a white wine changes/ if you find it objectionable. … taste takes practice. Sugar will balance flavors if I (you) over do a must. Time also can fix a high tannin. Mulberry isn’t supposed to last five years but with a slug of grape tannin it does.
Tannins; tannins are natural polyphenols. Polyphenols are a natural family of chemicals. Some give the nice red color in aronia (a super fruit) and the purple color in red grapes. The class of polyphenol called tannin is a polymer of catechin of variable length. There is a different flavor depending on polymer length. Plants produce tannin as a mechanism to resist insects/ predation. The flavor depends, therefore Scott sells a variety of clean tannins from several different plants. I have crab apples, if I describe the flavor early season / August is bitter (hard tannin), when fruit is ripe / September flavor is astringent (also called soft tannin) and pleasing. After frost the fruit is flavorless. In wine tannins have a similar flavor progression, therefore we speak of young aggressive red wines. I practice tasting fruit and even the skins of apple cultivars. Grape skins have soft tannin, seeds have hard tannins.
Chestnut tannin is a commercial soft tannin which I find in the store. A soft tannin / astringent flavor will magnify the flavor of acidity, tannin can be used to increase freshness of a fruity flavor. Testing flavor it doesn’t require a lot. A few grains picked with a tooth pick can improve the flavor of a glass of wine.
I put tannin in all wines. Sometimes I may add 2% aronia in a clear juice. I may steep 5 to 10% crab apple with a white grape juice to add soft tannins. I may run a mulberry with a teaspoon per gallon of grape tannin and then go to a club meeting and ask “can you guess what variety this is?” Tannin is magic, as a start I suggest get what the local store sells (or the Scott labs tannin kit) and take a toothpick to see how the flavor of a white wine changes/ if you find it objectionable. … taste takes practice. Sugar will balance flavors if I (you) over do a must. Time also can fix a high tannin. Mulberry isn’t supposed to last five years but with a slug of grape tannin it does.
I agree with Bob & David.
I add toast oak shreds or chips to all red grape wine prior to fermentation. It doesn't add flavor, but does provide tannin and stabilizes the color.
For non-red grape wines, in the past I added generic tannin powder at fermentation time to improve body and add structure.
Last fall I added finishing tannins to all wines: Chambourcin, Chelois, Pinot Noir [juice buckets fermented with Chambourcin & Chelois pomace], Chardonnel, and Vidal. For the whites (Chardonnel, Vidal) I used a tannin specifically made for whites. For the reds I used 3 different tannins in different containers, to see what the differences are.
If you're getting oxidation, then we're looking at O2 exposure and/or lack of sulfite.
Fermenting in an open container is the right thing to do, as yeast needs O2 for reproduction, and the fermentation emits enough CO2 to prevent oxidation. Post-fermentation? O2 may be yeast's friend, but it's wine's enemy.
If a wine is still fermenting when I move it to secondary storage, I will leave a larger headspace for a week or two, to avoid boilover. After that, I want 1" to 3" of headspace in a carboy below the stopper. I find that 1" may be a mistake, as when the wine warms in the spring as my cellar warms, the wine expands and I've had wine squirt through the airlock.
K-meta is a necessity. Unless someone is allergic to sulfite, there's not a good reason to not use it if longevity is expected. Wines made without K-meta typically have a shorter shelf life, as sulfite is an antioxidant, germicidal, and general preservative.
The standard dosage is 1/4 tsp per 19-23 liters of wine. I add K-meta at each post-fermentation racking, every 3 months during bulk aging, and at bottling time.
I add toast oak shreds or chips to all red grape wine prior to fermentation. It doesn't add flavor, but does provide tannin and stabilizes the color.
For non-red grape wines, in the past I added generic tannin powder at fermentation time to improve body and add structure.
Last fall I added finishing tannins to all wines: Chambourcin, Chelois, Pinot Noir [juice buckets fermented with Chambourcin & Chelois pomace], Chardonnel, and Vidal. For the whites (Chardonnel, Vidal) I used a tannin specifically made for whites. For the reds I used 3 different tannins in different containers, to see what the differences are.
If you're getting oxidation, then we're looking at O2 exposure and/or lack of sulfite.
Fermenting in an open container is the right thing to do, as yeast needs O2 for reproduction, and the fermentation emits enough CO2 to prevent oxidation. Post-fermentation? O2 may be yeast's friend, but it's wine's enemy.
If a wine is still fermenting when I move it to secondary storage, I will leave a larger headspace for a week or two, to avoid boilover. After that, I want 1" to 3" of headspace in a carboy below the stopper. I find that 1" may be a mistake, as when the wine warms in the spring as my cellar warms, the wine expands and I've had wine squirt through the airlock.
K-meta is a necessity. Unless someone is allergic to sulfite, there's not a good reason to not use it if longevity is expected. Wines made without K-meta typically have a shorter shelf life, as sulfite is an antioxidant, germicidal, and general preservative.
The standard dosage is 1/4 tsp per 19-23 liters of wine. I add K-meta at each post-fermentation racking, every 3 months during bulk aging, and at bottling time.
Thank you so much for that information!! I’m going to have to review my whole process. I didn’t know a lot of this stuff. Good information!!
by reading WMT often, you will learn something daily. I do. Thanks to the "Little old wine makers" who moderate and contribute so much
My last couple of kits I have passed on the included wood chips during fermentation. Guessing this is a big mistake? During racking, the chips clogged my pump hose which really isn't that big of a deal to unclog.
IMO, yes.
Buy muslin hops bags -- put the chips in a bag. Or better yet, make a racking jig like I did, wrapping it in a fine mesh bag to keep the chunks out.
I'm going to make 6-7 kits in the next two months and I'll go back to including the wood chips during fermentation. It makes sense they are included for a reason. Great information from you guys on this site! Thanks again.
Scott
Scott
This post on kit contents describes all the pieces, including fermentation oak.
When making a kit, I use all the components except the K&C and the finishing pack (sorbate).
I stopped using K&C as I found the quantities included in kits strips aroma and introduces a small amount of bitterness. From discussions on the forum, it appears that lesser quantities of K&C clear the wine with out excessive side effects. But since I bulk age long enough, fining agents are rarely necessary.
Sorbate? It's included in all kits as a fail-safe, to prevent newbies from making 28-30 mini-volcanoes, e.g., if residual sugar is present, the likelihood of a referment is very low. I backsweeten few wines, so it's not necessary since all mine ferment dry. That's why Dionysus gave us hydrometers, right?
Lots of good answers about tannins.
Another perspective.....
Some fruits have more tannins than others. It is up to the winemaker to add tannins or just let the existing character of the fruit carry itself. Yes, it's easy to add tannins, as there are many types to shape the wine. It is also up to the winemaker how to PROMOTE the tannins in the fruit, or skillfully subdue them. All the above comes with experience, sorry to say experience takes time and lots of trial and error.
Besides trowing in a hand full of oak chips or cubes (almost mandatory for some wines) here are some more delicate ways to add tannins that can be explored.
1) Keeping fermenting temperatures to within certain ranges. Warmer temperatures promote tannins and color, cooler temperature concentrate aromas, fruity notes, and demote tannins.
2) Yeast selection. Some yeasts absorb and smooth out tannins like 71B. Others accentuate tannins like D80. Look to the yeast specifications for that information.
3) Choosing timing wisely. Tannins are mainly in the skins, seeds and pulp of fruits. The contact time of skins and fruits allow more tannins to be infused into the must.
I hope this helps.
Barry
