Before we get into how to stop fermentation during winemaking, let us tell you about a love story, one as old as human civilization, maybe even older. This is a tale which started more than 8000 years ago. Wine and humanity started their journey around 6000 BC in Georgia and ancient Persia – today’s Persia.

However, that wine is nothing like the wine we consume today. The technology and wine recipes and methods of making were so different back then.

Since then, the methods have come along way – harvest and crushing and pressing might have stayed the same. Human touch is much more critical when it comes to crushing the fruit than the practical side of the machine pressing the grapes.

Fermentation can’t change as it is a chemical reaction that happens naturally. Today we understand the whole process a lot better to use it correctly and to our advantage.

The aging and bottling process has come a long way. This is since the first storing of wine in amphoras and dark, musty caves. However, nowadays, wine cellars and wine storage rooms are being created today. They have so much precision and thought to create the best place with no light, perfect temperature, and humidity levels.

Wine Making Process

The Harvest

The first step of the winemaking process is harvesting the grapes. There are good and bad seasons for wine. Sommeliers will say that a particular year was terrible for wine because the harvest didn’t go as planned.

Why wine from grapes? Well, it is because no other fruit responds to ethanol the way grapes do. They have the most amount of sugar from all the fruit. This helps them endure the amount of alcohol necessary for the beverage to be preserved.

However, the harvesting is not merely about the best way to pick the fruit, clean them, etc.

It is more about the timing. Choosing the right time to harvest is an essential part of the harvesting step. A group of advisors, farmers, and executives sit in a room and try to find the perfect date to start the harvest as it might have the most influence on the winemaking process.

Almost anyone in the business has a say in the process – from harvesters and farmers to people in the PR and marketing department. Picking grapes when they are physiologically ripe is crucial.

There are different ways of harvesting the grapes, but the two are most frequent – mechanically or by hand. In which the second one has taken the victory.

Most estates prefer hand-harvest as machines can be forceful and rough on the grapes, soil, and the vineyard.

Crushing and Pressing

Since the first invention of wine, crushing and pressing has been a crucial part of the process, and for a very long time, there was only one way of doing so.

But since the technology was evolving and the means to accomplish the same thing were getting better new ways of crushing and pressing have emerged – mechanical presses.

Mechanical presses are a faster process than men and women performing the harvest dance in barrels. However, like any argument against machines taking some part of our job, they lack the human touch when crushing the grapes.

Today’s mechanical presses might have lost the sentiment, but the winemaking process has gained speed and has improved the wine’s quality and longevity.

Fermentation

To understand how to stop the fermentation process in winemaking, you first need to uncover how fermentation works and what it is. So the fermentation process is the core step in winemaking. Without it, there would be no wine, no glass of wine a day keeps the doctor away attitude, no romantic evenings with your partner.

All the sommeliers, wine lovers, and vineyard owners owe everything to fermentation. This chemical process is a metabolic process that produces chemical changes in organic compounds. 

To summarize, fermentation is a process in which change affects the core components – it extracts energy from carbohydrates in the absence of oxygen. The science behind it is called Zymology.

Zymology or Zymurgy is an applied science that researches fermentation and its practical uses. How yeast and bacteria affect food and beverage and how to use them for our advantage – brewing, winemaking, and fermenting milk.

When grape juice is left alone for around 12 hours, the fermentation process begins due to the natural yeast produced in the air. However, there are some benefits to artificial yeast control, which many vineyards use and exploit. 

Creating a sterilized environment can significantly reduce any unnecessary risk in fermenting the wine. A controlled environment means no mistakes or marginally impossible chances for an error to occur, which means that the wine will ferment just the way it is supposed to.

When the fermentation begins, it lasts until all of the sugar turns into alcohol. We are talking anywhere from 1 week to more than a month – it has many things that it depends on. Climate, humidity, room temperature, and how much natural light is allowed in the room. All these things are vital to control so that the fermentation process would be perfect.

Clarification

After the fermentation has been completed – and alcohol has been created by siphoning all the sugar out of the juice, the clarification process can begin. And there is a theme to winemaking for any method. There are two ways of completing it – Racking and Siphoning. 

Some vineyards also tend to filter and fine wine for the bonus and control. These two processes aim to hook in the large solids and can be done with almost any form of filter. From a sterile filter pad to a regular coarse filter.

The clarified wine is ready to be changed to a new vessel and can begin the aging and bottling part.

Aging and Bottling

We are almost at the end of our journey. The last step is storing the wine – aging and bottling.

This last step is semi-optional, and I say that because the winemaker chooses whether he wants to bottle the wine instantly or if the aging process will be allowed to go on for much longer – totally dependable on the winemaker’s decision.

There are many different ways to store wine properly, and it depends solely on the people who are storing it – what is convenient for them mostly.

Bottle storing or stainless steel or even the musky feel of a large wooden oval is entirely up to the winemakers to decide how to store the wine.

How to Stop Fermentation in Winemaking

The fermentation process generally stops on its own when there is no sugar left so that you will have a dry wine, or when the alcohol concentration reaches about 14-18%, depending on the yeast strain. But how do you stop the fermentation process artificially in winemaking?

Stopping with Cold Shock

Of all the methods to stop fermenting, this one may be the best for one reason – this method does not affect the flavor potency and the aroma of the wine you are making. What I am saying that if you use this method, your wine will solely stop fermenting – nothing more and nothing less.

The method is straightforward – you cool off your wine to a temperature that makes the yeast stop functioning.

Pasteurization

This one is the most efficient way of killing the wine yeast without altering the wine. The method is quite simple in theory – overheat the wine so the fermentation will stop. Then cool it down abruptly and seal it.

However, this whole process can’t be done in an uncontrolled environment, making this method hard to pull off. It is quite challenging to maintain a constant high temperature for 15 minutes and even harder to pull off a fast cooldown.

Stop with Alcohol

Adding alcohol to wine to stop it from fermenting is the simplest of ways to stop the fermentation. Yeast stops working when the alcohol concentration exceeds 14 percent.

Final Thoughts: How to Stop Fermentation in Winemaking

To round things up, fermenting wine is a regular and crucial winemaking process – without it, there would be no wine. The fermentation can last from a week to over a month, but it can be stopped faster than expected by a couple of methods – adding alcohol, overheating, and pasteurization. 

It can be done for numerous reasons, but the main one is because winemakers believe that particular wine should ferment for a certain number of days. Any more or any less is not good enough.