Wine Fermentation Problems - Top 3 Reasons For Stuck Fermentation In Wine

Have you ever experienced stuck fermentation in wine before? Some wine makers experience this phenomenon where the wine started off fermenting normally - tons of bubbles and froths - and then after a few days the whole process seems to slow down drastically or even stop completely. If the above happened to your wine before, it just went through a "stuck fermentation".

Before we delve into the top 3 reasons for stuck fermentation in wine, it is necessary to first confirm that the wine is truly experiencing stuck fermentation. Bubbles and froths may not be a good indicator of whether fermentation is on-going. To make sure that the wine is experiencing stuck fermentation, it is better to measure the specific gravity of the wine using a hydrometer. If the reading is the same after 1-2 weeks, it can be said that the wine is stuck in fermenting.

One of the most common causes of stuck fermentation is excess sugar. Sugar is very important to wine because it is the "thing" that gets converted into alcohol. Yeast consumes sugar during fermentation and produces alcohol. With that in mind, some wine makers try to "play it safe" by adding excess sugar, or they add extra sugar in an attempt to achieve high alcohol level in their wine.

High sugar level is undesirable because it introduces a preservative effect on the wine. Thus, yeast will have problems multiplying and they will not be able to produce alcohol. Always use a hydrometer to check the sugar level before adding the yeast. For wine, the hydrometer readings should be within 1.07 to 1.09.

Another possible cause of stuck fermentation is due to the lack of nutrients. Yeast, being living organisms, requires the right mix of nutrients to survive and multiply. Thus, it is possible that the juice does not have the necessary level of nitrogen, oxygen, amino acids, vitamins, minerals, etc. The best way to resolve this issue is to use grape juice when you are making wine as it naturally contain the right mix of nutrients that is ideal for the yeast. For other fruit juice, it might be necessary to add yeast nutrient packets or yeast energizer. These products are specially designed to aid yeast growth.

The last possible cause of stuck fermentation is due to sulfites or preservatives. Always check to see if the fruit juice contains any preservatives as they are killer agents of yeast. Some wine makers also like to add sulfites such as campden tablet or sodium/potassium metabisulfite to sterilize the fruit juice prior to fermentation. If you are using pre-packaged juice, it is not necessary to add the sulfites as these products are usually sterilized before they are packaged. If you're using sulfites solutions to sterilize the equipments, wash the equipment again with water before using them.