How To Solve The Problem of Fermentation Stagnation?

Anyone who has worked with brewer's yeast knows that you need to give it a comfortable working environment to maintain its function. A stuck fermentation is when fermentation stops before all the available sugars in the beer have been converted to alcohol and carbon dioxide. If the bubbles in the airlock decrease before the beer reaches its final specific gravity, the fermentation may be stuck. Don't worry, there is a way to fix this. Before we discuss how to fix this problem, make sure your fermentation is stuck.

How to check if a fermentation is stuck

• The specific gravity of the beer is no longer decreasing or is very stable. If the hydrometer reading remains constant and higher than expected for three consecutive days, it indicates a stuck fermentation.

• The temperature of the fermentation area is between 65-72 degrees Fahrenheit. If the temperature is too low, the yeast cannot do its job. If the temperature is too high, the yeast will stop growing and excessive off-flavors will be produced.

What is a stuck fermentation?

A stuck fermentation occurs when the yeast stops fermenting before reaching the final target gravity instead of fermenting fully. A stuck fermentation is detected by observing a drop in pH over the first 24 hours. Beer ferments at an irregular rate, so don't worry after one day. A stuck fermentation occurs until the gravity readings are stagnant for 48-72 hours.

What are the causes of fermentation stagnation?

Fermentation stagnation has long been a major problem in the wine industry, affecting not only the quality of the wine, but also the economic benefits.

The most common causes:

• Poor yeast preparation and adaptation

• Nutrient deficiency

• Too little yeast input

• Insufficient nutrients in the wort to maintain yeast activity

• Too high sugar content

• Too low or too high temperature

• Too low pH value

• Poor inoculation technology

How to Prevent Stuck Fermentations

If you purchase or propagate quality yeast, you must keep it alive. To do this, store each yeast slurry in a sealed sterile container at a temperature below 42 degrees Fahrenheit but above freezing, and handle it in a sanitary manner to avoid bacterial growth or cross contamination.

The fermentation and fermentation process should be carried out at the correct temperature, avoiding sudden temperature fluctuations. Although you can almost always get the exact strain number from your supplier or manufacturer. But in general, ale yeast likes to survive in wort well below 80 degrees Fahrenheit, around 68 degrees Fahrenheit. Most lager yeasts grow between 45-55 degrees Fahrenheit.

Solve the problem of fermentation stagnation

Proper yeast preparation

Yeast rehydration is one of the most important steps in the fermentation process. Sterols play a role in maintaining the integrity and fluidity of the yeast membrane, thereby enhancing its resistance to alcohol.

Provide proper yeast nutrition to prevent fermentation stagnation

In the early stages of fermentation, yeast requires amino acids, vitamins and minerals to achieve sufficient colony growth without increasing temperature and pressure. Promoting the early accumulation of long-chain unsaturated fatty acids and sterols helps improve the endurance and survival rate of yeast throughout the fermentation process.

How to deal with a high initial Brix?

Adding water to adjust the initial Brix is a good way to control alcohol content and reduce the risk of stuck fermentation. There are two ways to add water: replace the original volume with water or add water directly. Adding water will help reduce the initial Brix, but it will also dilute the yeast nutrients, total acidity and phenolic compounds. Therefore, it is important to check and adjust the acidity, pH and total yeast acidity (YAN) to the appropriate level after adding water.

Preventing Microbial Contamination

Microbial contamination in grapes and must can severely affect fermentation and wine quality. To prevent stuck fermentations, it is important to control the microbial population and ensure that Saccharomyces cerevisiae is the dominant species in the fermentation process. Sulfur dioxide is the most commonly used antimicrobial, but it is ineffective at high pH, can inhibit and irritate Saccharomyces cerevisiae, and some spoilage microorganisms are resistant to it.

Temperature Shock

Both too cold and too hot can affect AF. Each yeast strain has its optimal temperature range, and any temperature outside of this range can cause yeast stress. If the temperature is too high (or the temperature suddenly rises at any time), the yeast may no longer be viable and will need to be re-inoculated. If the temperature is too low, try heating the wine.

How do you restart a stuck fermentation?

Check the temperature and adjust it. If you have a controlled fermenter environment, you may have learned that you can now aerate the wort to allow the yeast to breathe and thrive. To avoid off-flavors that may occur when waking up the yeast, you can refer to the following steps:

• Take 4 ounces (113 grams) of dry malt extract (DME), add water to a total volume of 1 quart (1 liter), and stir until the DME is dissolved.

• Add a small amount of yeast nutrient solution, boil the solution for 20 minutes, add water as needed, and cool to about 70 degrees Fahrenheit (21 degrees Celsius).

• Aerate and inoculate with a fresh yeast sample, and if you have a stir plate, continue to stir the wort you added.

• Let the wort stand at room temperature until it is fully fermented, then add this starter to the beer.

• For best results, the beer should be left in the fermenter during this period to release a lot of dissolved carbon dioxide.