Glycerin in Winemaking

updated 07/16/2024

I first started using glycerin decades ago when making liqueurs from extracts — it was a less expensive way of making good liqueurs. In a blender put 1 bottle of extract (1 to 2 oz), liquor (typically vodka or brandy, depending on type of extract), sugar syrup, and 1 oz glycerin. Blend to mix, and I had 1 quart (or liter) liqueur.

I made liqueurs without glycerin, but all tasted thin. The flavor and aroma were there, but adding glycerin perked the liqueurs a lot, with more mouthfeel (sensation on the tongue), and in general smoother.

In the last five years, I’ve started adding glycerin to my wines at bottling time, for the same reasons as adding to the liqueurs.

1. Mouthfeel

Comments about “mouthfeel” abound, but finding a good definition took searching. The best I’ve found is “texture”, the way tannin imparts dryness, acid imparts bite and/or sharpness, and glycerin imparts a thickness of the wine, so it more coats the tongue, gums, and cheeks. Up to a point, glycerin makes the wine tackier and improves sensation.

2. Body

Body is how rich and full the wine tastes. A thin wine is lacking in taste, and probably aroma, which affects taste. It’s easy to confuse this with mouthfeel, but they are different.

3. Smoothness

Wine can be harsh in different ways: too much tannin or acid can make the wine unpleasant. Glycerin may soften the harshness, making an unpleasant wine good.

4. Sweetness

Glycerin may impart a perception of sweetness, although it contains no sugar, nothing fermentable.

Note: While I realize that 1 US gallon does not equal 4 liters, for the purposes of this post, they are close enough for practical purposes.

How Much To Add?

Update: When I originally wrote this post, my recommendation was 1/4 oz (7.4 ml) to 1 oz (29.6 ml) of glycerin per gallon. Since then I’ve discussed the topic with others and have experimented more. Following is my current recommendation:

My updated recommendation is 1/2 oz (14.8 ml) to 1-1/2 oz oz (44.3 ml), and my starting point is typically around 1 oz (29.6 ml). For selected wines, such are Port-style wines, I may add more glycerin.

The safe method:

1. Pour a glass of the base wine as a baseline.

2. Add 1/2 oz to a gallon, stir very well, and taste.

3. Based upon that, add more glycerin, stirring well, and re-taste. Repeat as needed.

4. If it seems like it needs just a bit more, STOP. It doesn’t.

Use that ratio for the remainder of the batch.

There is no science to this — it’s all to taste. Trust your taste buds. as I said above, when you think it needs just a bit more, stop. It doesn’t.

Keep in mind that it’s always easier to add more than to take some out.

An alternative is bench testing, e.g., pour several glasses of wine and add varying amounts of glycerin. Stir very well, taste, and choose the favorite. I do not recommend this method as tiny amounts of glycerin are required in each glass, and stirring well enough to ensure the glasses are blended introduces O2.

What do I do?

I’ve been doing this long enough that I trust my own judgment. I taste the wine and decide how much glycerin is required. I add that amount to the batch, stir well, and taste again. Probably 90% of the time, my initial decision is good. But I have a lot of experience doing this, and it guides me.

This can be done with 1 gallon, so if too much glycerin is added, there’s more wine to add to dilute it.

Making It Dissolve

Glycerin is thick and getting it to dissolve completely can be difficult. Years ago I had a batch where there were globs of glycerin in the bottom of the bottling bucket, so most bottles got just enough and a few got WAY too much.

Following is a list of methods that have worked.

1. After the wine is in the bucket, start stirring the wine and add the glycerin in a very thin stream while continuing to stir. Although hand stirring works, a drill-mounted stirring rod works better.

2. Add the glycerin to the bottling bucket after the siphon has started, using the siphoning wine to rinse the measuring cup. Stir during the siphoning. This works fairly well.

3. Dilute the glycerin with 5 times its volume in wine and pour into the wine while stirring. This seems to work best as the globs of glycerin can be broken up in the smaller container, then better distributed when adding to the main batch.

Summary

In 2019 I made a second run wine that was barrel aged for a year adding 6 oz medium toast oak cubes in 54 liters (14.25 gallons) wine. I reserved a bottle without glycerin but added it to the vast majority of the wine. Two years later I opened the reserved bottle — it was undrinkable, the oak taste too harsh and overpowering. The addition of glycerin completely changed the wine. Most changes are not this significant, but it can happen.

As previously mentioned, add by taste, and go lightly with additions. When satisfied, stop.

Remember that the enemy of Good is not Bad. The true enemy is Better. As in “This is really good, but I can make it better!” 🙂