Primary Fermentation vs. Secondary Fermentation

[Fairbro1]

Ok, so I have a three-part question, and any help would be greatly appreciated. First, how do you know when the beer has passed through the primary fermentation phase and moved into the secondary? I understand the primary is all about simple sugars, easy for the yeast to digest and usually has the most activity but is there a way to measure and know conclusively.


Second, Once you pitch your yeast, is it a good idea to gradually (over days) bring the temperature up of your fermenting beer? I ask because I have the ability to temperature control with my set up and I understand the yeast, like warmth and become more active the hotter it is. Bouncing off my first question, it makes sense to me to bring the temperature up by a few degrees in the secondary fermentation, no?


Third, what is the average duration between pitching > primary > secondary > ready to bottle and condition?

 

[HighVoltageMan!]

First, how do you know when the beer has passed through the primary fermentation phase and moved into the secondary?

1. Gravity drops to within a few points of targeted FG
2. Lower activity in air lock/fermenter
3. Temperature spikes and starts to drop
4. You brewed this beer a billion times and you just know.

Once you pitch your yeast, is it a good idea to gradually (over days) bring the temperature up of your fermenting beer?

Depends on the yeast and style. Ales almost never need a temperature rise, they have more exothermic activity than lagers. Lagers can benefit from a rise toward the last days of fermentation, but if you ferment them warm (+64F) there is no need.

Primary and secondary fermentation is not nearly defined as one would hope. The two stages can happen at the same time toward the end of fermentation. The yeast needs to be active to clean up the beer, which would be the secondary. That means it can't be at final gravity for the secondary, the yeast needs to be in suspension.

The idea of primary and secondary is a little misleading. You can do both in one vessel, the yeast can clean up the beer pretty fast, a day or two. This is true even for lagers. Often people misunderstand conditioning as the secondary. Conditioning means the beer is taken off the yeast and cleared. This is done to prevent the yeast off flavors from autolysis getting into the beer. This is also somewhat exaggerated as well. The Germans are sticklers for getting the beer off the yeast as soon as possible, others no so much. If the yeast is removed prematurely, this can lead to problems as well.

I like to perform primary, secondary and a good portion of the conditioning in the same vessel. I never seem to have any problems, especially with lagers.

Third, what is the average duration between pitching > primary > secondary > ready to bottle and condition?

3-7 days from pitch for ales and the beer can be bottled, this varies with yeast strain and fermentation conditions. Lagers 7-14 days and the beer is ready for lagering. You could bottle condition the beer at the end of the fermentation and then lager it. The lagering just drops yeast and tannins/proteins from suspension for the most part. There are other things happening in lagering as well.

 

[Minbari]

Primary and secondary is more a location than an actually phase. People will rack to secondary to get the beer off the trub.I never have done it, there is a wild conversation about the use it

As for temp. I get my beer to pitch temp and hold it there until cold crash time. Other than if you are fermenting a lager where you might want to let it warm slowly over time to mitigate diacytl. Most beers are happy to ferment at one temp.

 

[Nosybear]

Ok, so I have a three-part question, and any help would be greatly appreciated. First, how do you know when the beer has passed through the primary fermentation phase and moved into the secondary? I understand the primary is all about simple sugars, easy for the yeast to digest and usually has the most activity but is there a way to measure and know conclusively.


Second, Once you pitch your yeast, is it a good idea to gradually (over days) bring the temperature up of your fermenting beer? I ask because I have the ability to temperature control with my set up and I understand the yeast, like warmth and become more active the hotter it is. Bouncing off my first question, it makes sense to me to bring the temperature up by a few degrees in the secondary fermentation, no?


Third, what is the average duration between pitching > primary > secondary > ready to bottle and condition?

Q1: There's really no such thing as secondary fermentation. The yeast ferments until it's finished and stops. What is sometimes called secondary fermentation is really clarification, the now hibernating yeast dropping out of suspension. Some flavor changes happen in this phase.
Q2: I generally let the yeast do after half the extract is done. I use a refractometer and correction spreadsheet to measure the remaining apparent extract daily and when it's half gone, I stop cooling the beer. I get good attenuation using this procedure.
Q3: There's really no good single answer. My rule of thumb is two weeks from pitch to package. Sometimes longer, sometimes less, depending on the yeast. Let your palate be your guide.

 

[HighVoltageMan!]

I think people often use the same term for multiple definitions. So to understand it better, you could just list the different stages of the yeast's cycle.

Lag- This is the period of time the yeast is acclimating to its environment after pitching. In the presence of oxygen it will use up it's glycine reserves to prepare to go from a quiescent state to an active state. The yeast will go into an aerobic state, taking in oxygen and using the oxygen to synthesis lipids to prepare for the log stage. Yeast growth is present, but not as much as the Log stage. With oxygen present the yeast will not produce as much co2 and alcohol, but instead, the yeast will use carbon in the form of sugar to build up biomass. As the oxygen is depleted the yeast will be begin the log phase provided conditions are suitable (pH, pitch rate, temperature, etc.).

Log Phase- This is when the yeast will switch from aerobic to anaerobic. The yeast will still build biomass in the anaerobic stage, but most of the carbon in the form of sugar will produce alcohol and carbon dioxide. Yeast growth in this stage is the greatest and the yeast will continue to grow until it hits its maximum cell density. The maximum cell density is determined by the available food and volume. No one really understands how the yeast is able to do this, but the yeast seem to know how many other cells there are and how much food is left.

Preparing for Quiescent or long term inactivity- As the food is depleted the yeast will prepare for a more dormant or quiescent state. Yeast never really go dormant except when dehydrated. The cell will begin to build glycine reserves and "clean up" the fermentation. The activity in the fermenter slows down, yeast will metabolize diacetyl and other by-products, thus "cleaning it up". Some German breweries will reintroduce fresh actively fermenting beer to speed up the cleaning up of the beer. In other words, they perform a secondary fermentation.

Dormant or Quiescent State- This is where the yeast will flocculate and slow it's metabolism. The glycine reserves help keep the cell alive. The reserves will last longer in a cold environment in the absents of oxygen. There are many other things that determine the length of time the cell can survive, but this is the major part of it.

If you understand the life cycle of the yeast it helps you to understand the brewing process better so you can brew better beer. I probably made some mistakes in my explanation, but this is a really complicated subject.

Letting beer age in a vessel absent or nearly absent of yeast is what I would describe as conditioning (or lagering) and not a secondary fermentation. This is when the beer will mature, clear and hopefully become better. Some homebrewers call this the secondary. It's really more of a bright tank minus the carbonation.

 

[BarbarianBrewer]

Excellent explanation @HighVoltageMan!

Some German breweries will reintroduce fresh actively fermenting beer to speed up the cleaning up of the beer. In other words, they perform a secondary fermentation.

+1 on this! You can't have a second fermentation without introducing new food for the yeast.