How to Sweeten Wine [Simple Instructions & Explanations]

Learn how to make sweet wine in the latest in our winemaking series. We carefully explain the different methods so you can decide which one is right for you.

The most popular wines are probably the sweet ones.

In the past, sweet wines were reserved for the nobles and kings because of their excellent ability to preserve the spirit of the fruit, expressed in its sweetness and in its fascinating aromas.

But making sweet wine sometimes requires more effort and dedication.

It's not just a matter of adding sugar to taste. You need to consider the effect you're having on the fermentation process very carefully. 

One of the most common problems among novice winemakers is how to sweeten wine.

We've got the answer today in our guide to making wine sweeter.

Key Differences Between Dry Wine and Sweet Wine

Sugar is a crucial component in winemaking. It's converted into alcohol in the fermentation stage, turning your grape juice into wine.

The main difference between dry wine and sweet wine is the amount of sugar that is dissolved into the wine, but crucially, not transformed into alcohol during the fermentation. 

This leftover sugar is called “residual sugar”. It's usually measured in g/L or grams per Liter.

The amount of residual sugar will determine the sweetness of the wine.

In dry wines the quantity of residual sugar is minimal, and you will not be able to taste it.

On the other hand, you should also know that in very fresh wines the sweetness is balanced by the acidity, therefore it is hard to notice.

Typically, sweet wines have lower alcohol concentrations than dry wines. This is because the fermentation process is stopped earlier to retain sweetness.

Making Sweet Wine: Challenges

The alcohol in wine is produced by the fermentation of the sugars by the yeast. The amount of sugar determines the quantity of alcohol produced during the fermentation process. 

To determine how sweet or dry is your wine, you should measure the specific gravity during the fermentation process. 

This is an essential part of winemaking and the measurement is taken using something called a hydrometer. This measures the density of a liquid based using buoyancy. Basically, the more sugar a liquid contains the 'thicker' or more dense it is.

Wines with a specific gravity lower than 1.000 are considered dry, while sweet wines generally have a specific gravity between 1.010 – 1.025.

Related: Got a sweet tooth? Don't miss our guide to unmissable sweet white wines next!

However, even if it’s relatively easy to measure the specific gravity, and therefore knowing when you have the desired sweetness, interrupting the fermentation process is not exactly simple.

Yeast usually stops fermenting when the wine reaches a certain alcohol concentration, or when the sugar is completely consumed.

Therefore, if you don’t start making the wine with enough sugar, you will probably end up with a dry wine.

If you’re not an expert winemaker, determining the right quantity of sugar to start with is rather difficult. 

How to Sweeten Wine

There are a couple of ways to sweeten homemade wines.

1. Retain Sugar by Stopping an Active Wine Fermentation

The best way to make sweet wine is to interrupt the fermentation process at an early stage. 

This stops sugar from being converted to alcohol. The remaining sugar remains in the wine as residual sugar.

This is how the sweet wines like Moscato that you know and love are made by their expert craftsmen and woman.

You can stop wine fermentation in a variety of ways:

Related: These budget sweet reds shouldn't be written off. See which bottles we recommend that don't cost the earth!

2. Add Sugar to Wine

The easiest alternative method is adding sugar to the already made wine post-fermentation.

This is done before bottling and is known in the industry as back sweetening.

Cane sugar is most commonly used but you can use all sorts of alternatives. Just remember to make sure whatever you add is completely dissolved and well stirred in.

Honey, beet sugar, and corn sugar are alternative wine sweeteners that you may want to try.

Here's how to sweeten wine with sugar:

How to Prevent Fermentation After Bottling

If you've just sweetened your wine, it's essential that you kill or remove all of the yeast in it before it's bottled.

If not, the carbon dioxide that's produced by the fermentation will cause such a pressure build-up that your bottles will fail.

Stopping an active fermentation (see the last section) is slightly different to preventing a fermentation from re-starting.

Here's how to stabilize a wine after back sweetening it:

Another simple method is to add a certain amount of sweet grape juice to the wine. 

However, this affects the taste and balance more than sugar, especially if your wine is made from another fruit. 

If you choose this method, pay attention to properly sterilize, filter, and clarify the wine. Store it at a low temperature in stainless steel tanks to prevent further fermentation.