What Is Primary and Secondary Fermentation in Wine?

There are different stages of fermentation, including primary and secondary fermentation. First, let’s start with primary fermentation.

What Is Primary Fermentation?

In short primary fermentation is the first fermentation. In this stage, yeast, a single-celled organism, transforms the natural sugars in grape juice into alcohol or wine and carbon dioxide.

You can tell when the primary fermentation occurs because there will be foam on the surface, and the airlock will bubble like a madman.

These changes will occur because the amount of yeast is expanding due to the large influx of sugar, nutrients, and oxygen. Its sort of like the wine is having a dance recital. Everyone is dancing around, trying to remember the choreography and hit the right move.

Primary fermentation is the most active and abundant stage of fermentation. Nearly 70% of the final alcohol content is generated during primary fermentation. Primary fermentation lasts for 3-5 days. After that, it moves into the next stage of fermentation.

What Is Malolactic Fermentation?

Malolactic Fermentation happens after primary fermentation. Essentially, sour malic acid naturally occurring in the grape must is transformed into a milder, lactic acid with a subtle flavor.

What Is Secondary Fermentation?

Secondary fermentation can be one of two things. First, it is an extension of primary fermentation, which converts sugar into alcohol after the wine is transferred from container to container. For example, the wine can be transferred from a stainless-steel container to an oak barrel.

Second, secondary fermentation can be a supplemental fermentation prompted once the primary fermentation ends. Typically, this is done by adding sugar (chaptalization) which is added to create sparkling wines.

After some time, the party will start to die down. The oxygen levels start to diminish, and most of the sugars will have been exhausted, causing the yeast population to stop growing.

The increase in alcohol levels will make it harder for the yeast to multiply and thrive. The cells will start to die and sink to the bottom of the container. This is why wine must be transferred to another container after the initial phase of fermentation is over. If not, the wine will have an unpleasant flavor from the dead yeast.

Secondary fermentation can last for 1-2 weeks. Things have drastically slowed down during this stage. Compared to the 70% of alcohol produced in the primary fermentation, a mere 30% of alcohol is produced during the secondary fermentation.

During the secondary fermentation, the foam will start to vanish, leaving behind tiny bubbles floating on the wine’s surface. The airlock will be fizzing every 30 seconds.

Unfortunately, there is no dividing line between primary and secondary fermentation. This is why you must pay attention to the activity around the airlock.

Is Secondary Fermentation the Same as Second Fermentation?

As if things weren’t confusing enough, right? In short secondary fermentation is not the same as second fermentation. Let me break down each term.

The second fermentation is when excess sugar that the yeast has not consumed starts alcoholic fermentation again. Second fermentation usually occurs when a wine is sweetened before all the yeast dies.

Second fermentation almost always happens by accident. That is, of course, if the goal is not to produce sparkling wine.

Sparkline wines are bottled before the yeast dies off. Additionally, a small unfermented grape is added to the wine, so the yeast has something to chow down on, trapping carbon dioxide in the bottle, which creates the bubbles we all love.

In contrast, secondary fermentation occurs once the wine has been transferred to a new container.

Is Secondary Fermentation Necessary for Wine?

Yes, secondary fermentation is necessary, especially if you want a clean, crisp wine. To do this, you need to eliminate most of the sediment. Therefore, the wine must be placed in a secondary fermenting chamber.

Can You Let Wine Ferment Too Long?

There is no such thing as fermenting wine for too long. Worst case scenario, the sugar and yeast reaction may be off.

This miscalculated reaction may be because you used the wrong type of yeast to produce the wine, or it was fermented using the wrong temperature. Nevertheless, the wine can still be salvaged even if you make one of these mistakes.

Final Thoughts

Primary and secondary fermentation are not the same thing. Now that you know the difference, you won’t confuse these terms with second fermentation and malolactic fermentation.