What happens when adding yeast to wort?

In this brief guide, we are going to answer the question “what happens when adding yeast to wort” with an in-depth analysis of the consequences or purpose of adding yeast into the wort which is the fermentation process. Moreover, we are going to highlight how the fermentation process can be affected by different factors.

What happens when adding yeast to wort?

The addition of yeast in wort leads to an important step involved in the formation of beer or alcoholic beverage, that is fermentation. During this process, the active yeast cells consume the oxygen and sugar and produce carbon dioxide in the wort. This process is affected by different variables, such as wort composition, aeration, temperature, health and amount of the yeast strains.

Adding yeast to wort:

Addition of yeast to wort, also known as pitching, is one of the most important steps while the formation of beer. The yeast is added to ferment the wort through maintaining the right concentration of sugar, oxygen, and carbon dioxide in the alcoholic beverages.

When the yeast is added, the active cells start dividing and increasing their population in the wort. The wort becomes saturated with carbon dioxide as the yeast cells feed on sugar and oxygen present in the alcohol or wort and produce carbon dioxide.

In the beginning, this fermentation process is slow as the yeast requires time to multiply and grow. Once the cells have grown enough, the process of fermentation starts as indicated by the signs of fermentation. Moreover, the conditions should also be monitored appropriately to carry out the process for which the yeast is added to the wort.

Yeast pitching:

Pitching is defined as the casting or addition of yeast into the wort. The pitching is simply the introduction of yeast source into the wort to do fermentation. Most commonly, the yeast is added in dried powdered form that is just sprinkled over the alcohol or wort.

The yeast is normally added in recommended amounts that is a recommended number of yeast cells per milliliter per sugar level.

Types of yeast added in wort:

Two types of yeast, dry and liquid yeasts, are normally used to ferment the beer or wort.

  1. Dry yeast:

Dry yeast is just sprinkled on the top of the wort without any preparation needed. Dry yeast usually does not require rehydration before addition to the alcohol but some people still rehydrate the yeast before adding.

In the case of rehydrating dry yeast, dry yeast powder is added into the water at about 80° F and allowed to sit in the water for about 15-30 minutes and then added (pitched) to the fermenter.

  1. Liquid yeast:

Liquid yeast is simply added into the wort when it reaches the temperature of about 80° F. Before the addition, gently press the contents inside the liquid yeast package to break down inner packet nutrients. Incubate the package for three hours or more at 70-75°F. Now open the package and add the contents of the package into the alcohol.

Factors affecting fermentation of wort:

The fermentation process carried out by yeast is influenced by a lot of factors. Some of these factors include:

  1. Composition of wort:

The amino acids present in the wort are essential for the growth as well as the activities of yeast relevant to fermentation in the wort. To perform a healthy fermentation process, the presence of amino acids in an adequate amount till the end of the beer formation is one of the most important factors.

Amino acids are collectively counted as the free amino nitrogen that is the basic thing required for yeast. Malted or mashed barleys have different amino acids composition depending upon the extent of malting. Moreover, greater malting can increase the gravity of wort due to the presence of high levels of amino acids in the wort.

  1. Aeration:

Along with proper amino acid composition, an adequate air supply is also required for the activity of yeast in wort. yeast, upon adding, readily uptakes the oxygen present in the wort to maintain its cellular integrity and thus regulate its activity efficiently.

  1. Amount of yeast:

Appropriate amounts of yeast are obtained by two methods: reusing yeast from previously fermented slurry and preparing through yeast starter.

Reusing yeast from the already fermented beverage enables to perform a healthy and quick fermentation process that simply involves the collection of yeast from the fermenter of already fermented beer and then the addition of this yeast into the fermenter containing wort. The recommended amount is 0.5 fluid oz of slurry per gallon of wort.

The second way involves the preparation of yeast starter from slants of yeast or the popular yeast smack packs. The active yeast is added to the wort in 1:10 or 1:20 ratios.

  1. The health of yeast:

The health of the yeast cells is also an important factor to be considered while fermenting beer or alcohol. To maintain the best health of the yeast, the yeast medium should be properly aerated as oxygen is required for sterols synthesis that maintains the strength of cell walls as well as the rapid growth.

  1. Fermentation temperature:

Inadequate temperature can affect the metabolism of yeast in several ways that in turn can affect the fermentation process. Some common metabolic processes affected by inappropriate temperature are lipid and sterol synthesis.

You can read the science of yeast here.


In this brief guide, we answered the question “what happens when adding yeast to wort” with an in-depth analysis of the results of adding yeast to wort which is the start of the fermentation process. Moreover, we discussed how the fermentation process is affected by variables, such as aeration, wort composition, amount of yeast, and temperature conditions.



https://www.howtohomebrewbeers.com/2016/07/pitch-yeast-into-homebrew-hydrate.html#:~:text=The%20short%20version%20is%20 if,and%20 fermentation%20will%20not%20 occur.


Mahnoor Asghar is a Clinical Nutritionist with a bachelor's degree in Nutrition and Dietetics. She is compassionate and dedicated to playing her part in the well-being of the masses. She wants to play a fruitful role in creating nutrition and health-related awareness among the general public. Additionally, she has a keen eye for detail and loves to create content related to food, nutrition, health, and wellness.