Questions about primary and secondary fermentation

[Dehitay]

I've gotten a deal of mixed information on primary and secondary fermentation. Some sources say primary fermentation takes 8 days. Some sources say it takes 3 weeks. If I had to guess, it probly varies on a number of different factors, and the most important factors are probly size of brew and amount of yeast used to start it.

I might be making things more complicated on myself here because while I know I use one gallon jugs, I've been using about a cup from a fermenting brew to start a new brew fermenting instead of adding new yeast packets. So I don't even know how to calculate how long primary fermentation should take.

Is there a specific gravity I can measure for that pretty much determines when primary fermentation is over? I've been told if I want to add spices, it's best to wait for secondary fermentation, but I can't currently tell when that is.

And if the specific gravity gets down to around 1, is it safe to put a cap on the bottle even if it's still producing gas without fear of the bottle exploding? Or should I just wait till it stops producing any gas?

 

[Arneba28]

Secondary fermentation is nothing clearing and aging. Your primary is over when your hydrometer tells you that fermentation is over. Meaning when you have reached your finally gravity. That is when you start secondary.

 

[Dehitay]

Secondary fermentation is nothing clearing and aging. Your primary is over when your hydrometer tells you that fermentation is over. Meaning when you have reached your finally gravity. That is when you start secondary.

The packet of yeast I started with doesn't list a final gravity. If I'm not using enough sugar to kill off the yeast, should my final gravity be 1? Some of my batches still seem to produce carbon dioxide after reaching that level although at a much slower rate.

 

[Arneba28]

Your final gravity is dictated by the amount of fermentable sugars in solution, and the tolerance of the yeast. Your final gravity will/should never be 1. There is always something unfermentable that will leave you at say 1.005 or 1.01 for even the lightest beers. Also the sugar does kill off the yeast. It eats it. My next thought is you might be transferring an infected batch of yeast from one batch to the next if you're repitching slurry

 

[Arneba28]

My only reason for thinking that is because your FG is so low. If you're getting an FG of 1.000 you got something funky going on

 

[Yooper]

Cider can finish below 1.000- depending on the yeast strain and the OG. I've had some ciders finish at .990, same as my wines, if I use a wine yeast strain. Using ale yeast, many ciders finish at 1.004-1.008 or so.

I rack out of the primary when my cider fermentation is slowing, or done. Then I put it in the carboy, top up, and rack again whenever lees are 1/4" thick or more, or after about 60 days. Once it's totally clear, I package. I have to admit that I'm pretty lazy, though, and the last batch I finally kegged and bottled not long ago was from fall 2013. I had 13 gallons sort of hidden, and kept procrastinating. It turned out really good, but that's not usual for me. I usually bottle or keg by about 6-9 months old.

 

[Arneba28]

That time I just realized I was in the cider forum and not beer. Wtf. Nothing of what I said applies anymore lol

 

[Arneba28]

That time I just realized I was in the cider forum and not beer. Wtf. Nothing of what I said applies anymore lol

 

[Dehitay]

All right, thanks for the help guys. I'll start secondary fermentation when my specific gravity starts reading low enough. I was never sure about deciding based on time.

 

[Maylar]

Temperature also affects the speed of ferment and the final gravity. At 60°F an ale yeast might finish at 1.004, at 68°F it might go below 1.000. A good rule of thumb (in my experience) is that if you rack to secondary at 1.008-1.010 you'll have very little lees at the end when you're ready to bottle. You can leave it in that state as long as you like for aging, or bottle it when SG finally stabilizes.

I never cap a jug until 2 months has passed in secondary.

 

[Mainer]

That time I just realized I was in the cider forum and not beer. Wtf. Nothing of what I said applies anymore lol

Glad you did it first, because I was about to give a sermon about how mash temp affects final gravity, which *definitely* doesn't apply to cider.

 

[MarkKF]

Secondary fermentation is nothing clearing and aging. Your primary is over when your hydrometer tells you that fermentation is over. Meaning when you have reached your finally gravity. That is when you start secondary.

I switch to secondary when fermentation slows not stops. Maybe 1.010! Then let it finish in the secondary. Gives it some CO2.

 

[ten80]

All right, thanks for the help guys. I'll start secondary fermentation when my specific gravity starts reading low enough. I was never sure about deciding based on time.

I think some of your confusion stems from the misnomer that is "secondary fermentation." Let me explain why that is.

For either beer, wine, or cider, primary fermentation is the fermentation of your original sugars. Wort, juice, or must plus yeast equals primary fermentation. Simple.

Now the part that hangs up new brewers is secondary fermentation because the term is used ubiquitously to describe what is essentially a clarification process. Transferring an actively fermenting liquid to a second vessel does not generate some sort of novel, i.e., "secondary" fermentation. Rather the transfer serves only to leave lees behind. The secondary fermentor (carboy) is not causing a secondary fermentation and is simply acting as a bright tank for clarification. Some primary fermentation may continue in the second fermentor if the cider was racked prior to reaching full attenuation.

That said, secondary fermentation does exist and would consist of a second fermentation caused by:
1. The addition of more fermentables (fruit, sugar, etc), or
2. Addition of a novel yeast or bacterium that continues fermenting the original sugars

So in short, forget the term "secondary fermentation" and simply ask yourself when you want to transfer the cider over to an empty carboy for clarification, aging, addition of finings, etc. As many have said, that generally should be done when your primary fermentation has completed or is very near completion.

 

[Northern_Brewer]

I've gotten a deal of mixed information on primary and secondary fermentation. Some sources say primary fermentation takes 8 days. Some sources say it takes 3 weeks. If I had to guess, it probly varies on a number of different factors, and the most important factors are probly size of brew and amount of yeast used to start it.

Add in the sugar mix of the juice/wort and the strain of yeast involved - some yeasts are Usain Bolt, others are Homer Simpson... I'm running some yeast experiments at the moment, the T-58 was going mental within just a few hours, the others were a bit more sedate.

The only way to tell is when you've got a stable gravity - there's no single magic number. Some yeasts munch up anything and everything and will give you a dry result with a low FG - high attenuation, some yeasts (like a lot of traditional English cask beer yeasts) are much fussier about eating complex sugars, leave more food behind and the result is a bit of sweetness and a higher FG - low attenuation (which is generally associated with yeast dropping quickly and well, which is desirable in cask beer).

Attenuation is less of an issue for cider than beer as in general the sugars in juice are much simpler than in wort, so the yeast find it easier to munch through apple juice. But you work out when it's finished the same way - when the gravity is stable.

 

[ten80]

Northern Brewer, did your T58 turn out extremely sulfury? I did a cider with T58 and one year later am still waiting for the sulfides to subside. Impossible to drink as is.

 

[Northern_Brewer]

Don't know yet, only pitched on Sunday - and this was beer rather than cider, although one reason for doing the beer now is to get a bit of a feel for some different yeasts for the apples I'm hoarding at the moment. I guess that it's so vigorous that there's a danger it runs out of nutrients in cider, which is when it starts stripping nitrogen from cysteine and releasing sulphur.

 

[Yooper]

So in short, forget the term "secondary fermentation" and simply ask yourself when you want to transfer the cider over to an empty carboy for clarification. As many have said, that generally should be done when your primary fermentation has completed.

Winemakers and cidermakers often use a secondary fermentation. Generally, the wine is moved to a carboy from a primary when fermentation slows (usually under 1.020) and allowed to finish there, under airlock. It is also topped up at that time. It will finish fermenting, and then racked when lees are 1/4" thick, or in 60 days if lees don't form that thick.

Sometimes wines or ciders throw a lot of lees, and it's racked again as needed.

Fermentation usually does finish in a secondary fermenter. Also, if it is topped up appropriately, juice/must will create another small fermentation.

 

[Maylar]

Some people insist that the only "true" secondary fermentation is MLF, where a different bug (bacteria, not yeast) does malolactic conversion. What is commonly referred to as "secondary" in the beer/wine/cider/mead community is actually a continuation of the process that started in primary.

That may be technically correct, but at least in cider making the act of racking can have more significance than simply clarifying. Racking also reduces the yeast biomass and removes a source of nutrients (dead yeast in the lees), which has the effect of slowing down the ferment. That's an important step in some cider making processes. Is it a "secondary" process? Maybe not, but by convention that's what we call it.

 

[MarkKF]

That’s why I call it primary vessel and secondary vessel. Referring to the first and second carboy not what’s actually occurring.

 

[ten80]

Winemakers and cidermakers often use a secondary fermentation. Generally, the wine is moved to a carboy from a primary when fermentation slows (usually under 1.020) and allowed to finish there, under airlock. It is also topped up at that time. It will finish fermenting, and then racked when lees are 1/4" thick, or in 60 days if lees don't form that thick.

Sometimes wines or ciders throw a lot of lees, and it's racked again as needed.

Fermentation usually does finish in a secondary fermenter. Also, if it is topped up appropriately, juice/must will create another small fermentation.

I don't disagree with the processes and their purposes as you describe above, however I believe that all except the addition of top-off juice would be inaccurately labeled as a "secondary fermentation." Why not use the very clear terms "clarification", "setting", "fining", or "racking", in a secondary fermentor (a vessel, not yeast as the fermenter) rather than the antiquated misnomer that is "secondary fermentation" which confuses beginners and advanced brewers alike.

 

[Yooper]

I don't disagree with the processes and their purposes as you describe above, however I believe that all except the addition of top-off juice would be inaccurately labeled as a "secondary fermentation." Why not use the very clear terms "clarification", "setting", "fining", or "racking", in a secondary fermentor (a vessel, not yeast as the fermenter) rather than the antiquated misnomer that is "secondary fermentation" which confuses beginners and advanced brewers alike.

Well, it might be antiquated, but some of the terms that we use that are old and still in common usage now and it's not incorrect to say "secondary" when talking about topping up in a carboy for the first time.

There are some terms that drive me crazy, like "back sweetening" to mean sweetening a wine or cider. That one actually has a distinct meaning, but has been misused for so long that it's become very common for new winemakers to use it to mean sweetening the wine or cider after fermentation is over. It bugs me, but I don't go around correct people behind mentioning it once in the "cider for beginners" sticky thread. I like people to be informed of correct terminology, but don't want to go beating them on the head with my interpretation of every nuance of meaning.

 

[madscientist451]

I've gotten a deal of mixed information on primary and secondary fermentation. Some sources say primary fermentation takes 8 days. Some sources say it takes 3 weeks.

I don't even know how to calculate how long primary fermentation should take.

Is there a specific gravity I can measure for that pretty much determines when primary fermentation is over?

And if the specific gravity gets down to around 1, is it safe to put a cap on the bottle even if it's still producing gas without fear of the bottle exploding? Or should I just wait till it stops producing any gas?

Quick answers, in order of the above.

--There are too many variables to determine when primary will be done, especially with cider. Your/juice apples will probably be different than what I can usually get and the differences can vary from one farm to the next. So don't worry about it, when its done, it done.

--When you take gravity readings over several days and it doesn't change its probably done, but if the gravity is higher than you expected, you could have a "stuck fermentation".

--No don't put a cap on the vessel, keep an airlock on it because it will continue to let off Co2 and in might not actually be all the way done.
I leave my cider in carboys with airlocks on for 6 months or more, but that is somewhat excessive, start drinking it when it tastes good.

 

[Scrumpy!]

I generally agree with Yooper that the terminology is unclear and it may not serve a larger purpose to get in a discussion about it but since so many have jumped in, I will raise by a nickle.

Many cider makers started by brewing beer and have carried over the terminology which is sometimes the cause of some misunderstanding. Cider making is not much different from wine making. Did you ever hear of anyone "brewing" wine? Not likely. We brew tea, coffee, beer, sake or witch's brew and the common thread is heating something to brew it. Heat is generally our enemy in cider or wine making except to pasteurize it.

Primary fermentation? It is almost universal on this and many other fora to describe the first stages of primary fermentation (lag phase + log or turbulent phase) as primary and the third phase of primary fermentation (stationary phase) as secondary. In the professional wine literature, secondary or even tertiary fermentation is initiated by adding new yeast or bacteria to start a completely different population of microorganisms. For example, once primary fermentation is complete, you might add malolactic bacteria to initiate a secondary fermentation to reduce the acid content. When you bottle that, you might add a specific yeast like champagne yeast to initiate a tertiary fermentation to generate carbonation.

Primary fermentation is complete when the initial population of yeast has exhausted all the sugar in the must, it runs out of yeast available nitrogen (YAN), it gets infected by a spoilage organism or you stop it by cold crashing, pasteurizing or some other technique which kills off the population or overwhelms it.

From a process standpoint, you seem to be wondering when to move from your fermentation bucket to a closed container. Most of us do that when the turbulent (log) phase has quieted down to the point where it can no longer burp a slug of must into a fermentation lock on a closed container with very limited headspace. At this point the yeast in the primary fermentation has fully passed from aerobic to anaerobic metabolic pathways. This is when you should be concerned about excluding oxygen from your quietly fermenting must.

Finally, I frequently see references to specific gravities below 1.000. Yes, they can get that low but keep in mind that your final liquid is now a mixture of water, ethanol and carbon dioxide, not sugar and water. Pure water has an SG of exactly 1.000 at standard temperature and pressure (4 deg C and 1 atmosphere) by definition. A 7% mixture of water and ethanol with no residual sugar has an SG of a little less than 0.987. Add some dissolved CO2 and it can go a little lower.

The assumption when you use a hydrometer or refractometer is that the liquid is water containing a soluble compound like sugar. However as the alcohol content of the liquid rises, this assumption becomes a little less applicable. The density trends down with fermentation as alcohol and CO2 replace sugar so the hydrometer can give a reading below 1.000. The refractive index of alcohol is not the same as water so your refractometer gives you a spurious reading too. If you really want to know the final gravity, you need to boil off the alcohol before making your measurement. This can be done by heating the sample to 170 deg for five minutes or so then letting it cool down to whatever your hydrometer is calibrated to. This also removes the CO2, another contributor to SG measurements below 1.000. There are corrections you can make to use a refractometer but they require some further assumptions that make it impractical.

 

[ten80]

Well, it might be antiquated, ...

There are some terms that drive me crazy, like "back sweetening" ... It bugs me, but I don't go around correct people behind ...

No need to call me out.

Please consider that I posted to clarify a the OP's confusion about the use of "secondary fermentation," not to randomly interject my personal feelings on the matter.

Notice that the OP has not returned to this thread following our discussion of semantics.

Scrumpy's post is a nice ending note with some good info that should probably go in a sticky for all to reference. Lets leave this discussion at that.

Cheers,
Christophe