Bitter Wine? Here’s What’s Causing It

If your wine tastes bitter, something in the process went off.

Bitterness is one of the most common issues in homemade wine, and it’s often confused with acidity or alcohol harshness.

The key is understanding what’s actually causing it, because not all bitterness comes from the same place.

What Does “Bitter” Actually Mean?

Bitterness is that dry, lingering taste that sits on your tongue, especially at the back of your mouth.

It’s different from sour (which is sharp and acidic) and different from alcohol burn (which feels hot).

Most bitterness comes from tannins or over-extraction.

Cause #1: Too Much Tannin

This is the most common reason.

Tannins add structure to wine, but too much can make it harsh and unpleasant.

If you added too much wine tannin, or if your kit already contained tannins, the flavour can become overpowering.

Young wines also tend to feel more bitter before tannins soften over time.

Cause #2: Wine Is Too Young

Bitterness is often strongest right after fermentation.

As wine ages, tannins and other compounds settle and integrate.

In many cases, what tastes bitter now will smooth out with time.

Proper aging conditions also matter. Using the right vessel, such as a glass carboy, helps wine mature more cleanly and reduces harsh flavours over time.

Cause #3: Sediment Contact

Leaving wine sitting on sediment (lees) for too long can introduce off flavours, including bitterness.

Proper racking is important to separate clean wine from unwanted material.

Using a siphon helps transfer wine cleanly without disturbing sediment.

Cause #4: Fermentation Issues

Stressed yeast can produce undesirable compounds that contribute to bitterness.

This often happens when:

• Fermentation temperature is too high
• Yeast lack nutrients

Using yeast nutrient and a reliable wine yeast helps prevent this.

Cause #5: Imbalance in the Wine

Sometimes the wine isn’t overly bitter — it just lacks balance.

If there’s not enough acidity or body, bitterness stands out more.

Lower-quality or inconsistent kits can also produce wines that feel harsher or more bitter, especially when young. Using a reliable kit, like those in our RJS wine kits collection, helps produce smoother, more balanced results from the start.

Small adjustments with acid blend can help bring the wine back into balance.

Can You Fix Bitter Wine?

In many cases, yes.

Let It Age

This is the easiest and most effective fix.

Time softens tannins and reduces harsh edges.

Adjust the Balance

Bitterness often improves when the wine is better balanced.

• A slight increase in acidity can brighten the wine
• A small amount of sweetness can soften bitterness

For sweetness adjustments, see our guide on back-sweetening wine.

Degas the Wine

Residual CO₂ can exaggerate harsh flavours, including bitterness.

Proper degassing can improve the overall taste.

Learn more here: degassing guide.

How to Prevent Bitterness

• Measure tannin carefully
• Don’t rush the process
• Rack at the right time
• Keep fermentation conditions stable

Most bitterness issues come from small mistakes that are easy to avoid once you know what to watch for.

Final Thoughts

Bitter wine doesn’t mean the batch is ruined.

In many cases, it just needs time or slight adjustments to improve.

Understanding the cause is what allows you to fix it and make better wine next time.