Top tips to stop fermentation in winemaking

Fermentation is a vital part of wine making and as a winemaker, you can't frown at the process. However, stopping it is one of the biggest challenges winemakers experience. Grape juice has very rich sugars and yeast is added into the juice to consume the sugar and turn it into alcohol. Naturally, fermentation stops on its own when all the sugar is consumed or when the concentration of alcohol ranges from 14-18%.

To qualify for the best wine Texas status, one needs to know how to stop fermentation once the desired level of sweetness, appeal and flavour has been achieved. The natural fermentation process can be artificially altered. You can opt to pause it, speed it up, or stop it altogether.

Actual steps to stop fermentation of wine1. Use of alcohol to stop wine fermentation

This is one of the easiest ways to stop wine fermentation as well as increase the wine shelf life. Previously, we had pointed out that yeast fermentation stops once alcohol concentration is between 14-18% depending on the strain of yeast.

To make this happen, Texas wineries use the below steps:

• Remove wine sediments by racking the wine in a sterilized demijohn.
• Add alcohol into the wine to attain an alcohol concentration of about 16%. It is important to note that you are only allowed to add vodka, brandy or grape distillate alcohol.
• Let the wine sit for a week for you to see if fermentation continues to take place or not. If no further fermentation occurs, rack the wine again and then bottle it.

The major disadvantage of using this method is that the flavor and smell of the wine are altered especially if vodka is used. For this reason, grape distilled is encouraged.

2. Using cold shock to stop fermentation

It is the only method that preserves the aroma, potency, taste, and sweetness of the wine. At 50F° / 10°C yeast goes into hibernation and precipitates at the bottom.

To do this you have to:

• Put the wine in a cold room or a refrigerator at 45-50°f for 3-5 days. Ensure the temperature remain the same and above the freezing point.
• Check if there is partial precipitation of sediments at the bottom of the demijohn.
• If there are sediments, rack the wine in a sterilized demijohn to remove the sediments and ensure the temperature is at 55-60°f. Be careful not to filter some yeast with the wine during racking as you will have to repeat the process again.
• Leave the wine at normal temperature for a week and look out for any precipitation. If there is, repeat the process again. Otherwise, bottle the wine.

3. Using pasteurization to stop wine fermentation

It is said to save the best for last. Pasteurization is the most effective method used by the best wineries in Texas to stop fermentation. Yeast dies at 104°f so the wine has to be heated above this point to stop fermentation.

To do this, follow the following steps.

• Make sure the wine is racked in a sterilized jar.
• Afterward, heat up the wine to 158°f and maintain this temperature for 10-20 minutes. At these temperatures, yeast and any other organisms in the wine are killed.
• Cool the wine immediately and as fast as possible to about 50-61F°.
• Bottle the wine immediately and if possible hermetically seal the bottle.

One of the greatest challenges in this process is maintaining the wine at the same temperature for 15 minutes and later cooling it quickly enough. Try your best to minimize the contact of the wine and outside environment after this process and the results will be so worth the efforts.

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