What Causes Wine To Go Bad During Winemaking?

When you are going to make a perfect wine of your favorite taste, maybe it gets wrong sometimes. You’ll think that you have followed all the instructions and directions carefully, and then what makes it wrong? What makes it taste awful or what makes because it’s bad quality? Some common possibilities may happen while making wine. In any case, when something happens badly, don’t discourage yourself, just raise your head and start making wine again.

Sediments in bottle

If you have added potassium sorbate to the liquid before the completion of the fermentation process and start budding of yeast, it cannot kill the yeast but can slow down the process of budding. Because the generation of yeast buds causes the re-fermentation process in the container. To protect this from happening, a wine hydrometer is used to read the specific gravity.

Stuck fermentation

In some cases, the process of fermentation stuck before reaching approximately, 0.998 specific gravity. This could happen due to many reasons and can restart again with using some yeast such as:

Separate ½ gallon of liquid and add 1 pack of champagne yeast in addition with the 1 packet of yeast energizer, mix all the material in a warm area. After this mixing, a fine fermentation process started within 8-16 hours. Once the process starts, add this separated must mixture to the original must.

In the case of incomplete or disturbed fermentation, produced wine may give paint-like or with chemical scent flavor. Unfortunately, when the wine is produced with a chemical scent, there is no possible way to make them taste better.

Using distilled water

While making wine, you can use bottled water as well as tap water. Keep in mind, that all watered bottles are not the same, some may be distilled or some may not. Before choosing the water bottle, make sure that the water bottle should not be labeled with distilled water, it is a bad thing for winemakers. Choose the bottle with the label of spring water, mineral water, or any other label. There are two main reasons for the bad effect of distilled water in winemaking. First, there are no minerals present in mineral water. Second, it is free or excess of oxygen.


If you have used a low-quality or defective cork, then it may cause a bad flavor in the wine. Due to the defective cork, air may enter the wine bottle and start oxidizing. As a result, wine gets an unpleasant flavor in it. To avoid this problem, high-quality cork is used such as Premium VS1.

The appearance of bubbles in still wine

If you have used the unsterilized bottle for wine packing, it mat starts re-fermentation again. This is because the present yeast starts eating the left sugar.


During winemaking, liquids are transferred from one container to another container leaving sediments behind at the bottom of the container. This is called racking. The main purpose of racking is to remove the yeast sediments from wine and to prevent the wine from getting a taste from yeast sediments.


Adding wood to the wine for aroma may cause it to go bad. It can give an unpleasant taste due to prolong wood-aging wine.


In winemaking, a siphon hose is used to fill up liquid from the container. Splashing is another problem with wine. Make sure that during racking and filling, the siphon hose should reach the bottom of the container and start filling from the bottom.


Residual Carbon dioxide gas is important to remove from wine. If you fail to remove the gas, it causes the clarifying agent to float on the surface of the wine and make it bad. Before the process of degassing, must add metabisulfite to prevent it from oxidation. Try to make wine in a carboy, which makes the degassing and mixing easy. In a carboy, it is easy to roll and lay down on its side during mixing.


Sterilization is the most important throughout the winemaking. All equipment used in winemaking should be clean and clear. Siphon tubes should be of great plastic and used equipment should replace with new equipment periodically. Before using the equipment, check that it should be clear of any stretches and damage.

All vessels, containers, tubes, and other equipment should be washed and dried otherwise it can give a soapy taste.

Specific gravity reading

Specific gravity reading has special roles in winemaking. This reading shows whether the process of fermentation is completed or not, or it is ready to enter into the next phase or not. Perfect specific gravity should be taken at 15C when the wine is fully degassed.

Strong vinegar quality

This develops when the wine is exposed to the oxygen of the air and produces the smells of volatile acidity and acetic acid. This action is done by the rogue yeasts present in the winery.

Smells of rotten onion, eggs, and cabbage

When wines are produced in the presence of less oxygen, it starts the development of volatile sulfur compounds, such as mercaptans. These wines are called “reduced wines”, as they are prepared in the absence of oxygen. This flaw happens a few minutes after the opening of a wine bottle. You can eliminate this smell by adding a small amount of copper to your wine glass before adding wine to it. Copper highly reacts with the sulfur compounds to eliminate this unpleasant smell.

Fermentation has already been completed

Sometimes, winemakers wait for the fermentation to be done, but in actual fermentation is already completed. Commonly, fermentation is done in 4-6 weeks, but in very rare cases it may be complete in 5-7 days. This could only happen if all the conditions are favorable and standard. After waiting for so many days, winemakers check the wine with the hydrometer; they found that fermentation has already been done. This is not a fault but, it happened rarely.

Too old yeast

The juice prepared to add into the wine is called must. If fermentation in the must is running very slowly or starts hardly, one thing to notice is “how old the yeast is”? The yeast used in wine is a kind of living organism with a limited life span. Before purchasing the yeast, make sure that it is present in a freeze-dried state. For use, this fried state is added into the liquid to convert it back to its natural state.

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