Fermentation effect produced during beer fermentation?

How does wort evolve into a fresh, tasty beer? What kind of material changes does the wort undergo in the fermenter? With all kinds of questions, let us come to the beer fermentation process.

Fermentation is the conversion of the glucose in the wort by yeast into ethanol and carbon dioxide gas. Before fermentation begins, the cooled wort needs to be transferred to the vessel where the yeast is added. The final fermentation is completed through three processes of primary fermentation, secondary fermentation and conditioning stages. The fermentation process generates a lot of heat, and the tanks are constantly cooled to maintain the proper temperature.

1. Fermentation effect produced by primary fermentation 

Yeast growth occurs during primary fermentation, when the yeast is introduced into the cooled wort, the primary stage of fermentation begins. Yeast rapidly utilizes available oxygen to produce an important compound for culture expansion. When the oxygen is gone, the yeast transitions to the anaerobic stage and most of the wort sugars are reduced to ethanol and carbon dioxide. Effects of primary fermentation include: consumption of dissolved oxygen, acidification/lowering of pH, yeast growth or culture expansion, ethanol and carbon dioxide production, production of flavor compounds such as esters, diacetyls, sulfur compounds, etc.

Primary Fermentation Temperatures: Ales: 62-75 °F (17-24 °C), Wheat and Belgian Styles: 62-85 °F (17-29 °C), Lagers: 46-58 °F (8- 14°C).

Fermentors manufacturing

2. The fermentation effect produced by the secondary fermentation 

Diacetyl reduction occurs during secondary fermentation. Secondary fermentation refers to the stage of fermentation after most of the sugar in the wort is consumed, the fermentation rate drops sharply, most of the sugar is eventually used up, and some secondary metabolites are converted by yeast. Yeast begins to flocculate and settle due to increased alcohol content and depletion of sugar and nutrients. The effects of secondary fermentation include: reduced ethanol and CO2 production rates, diacetyl conversion, reduction of some flavor compounds through yeast metabolism or CO2 scrubbing to terminal gravity, yeast flocculation and settling initiation.

Secondary fermentation temperatures: Ales: Same as primary fermentation (higher temperatures increase diacetyl reduction), Lagers: 40-60 °F (4-15 °C). Some brewers allow the beer to be warmed up to speed up the reduction of diacetyl. This elevated temperature usually only lasts 24 to 48 hours. Wheat and Belgian beers: Same as primary fermentation (higher temperature increases diacetyl reduction).

3. Conditioning phase: 

This stage is when final gravity is reached and the tank cools to refrigeration temperatures (31-38°F, 0-3°C). The yeast then continues to flocculate and settle, conditioning the beer by reducing various undesirable flavor compounds.

The effects of the conditioning phase include: the removal of most of the yeast from the beer, reducing the stinging taste of alcoholization, and the reduction of sulfur compounds, diacetyl and acetaldehyde to stabilize the beer flavor.

Vertical bright beer tanks

The above is the relevant content of the fermentation process in craft beer. You can browse our news blog to learn more about beer knowledge. Welcome to discuss with us!