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View Full Version : dangerous questions; why and how



jollycynic
06-19-2010, 04:23 PM
Heya, I'm preparing to start this fun and eventful experiment in homebrewing and despite some reading and rereading, I find myself puzzled on a couple of points regarding secondary fermentation.

For one, I see a lot of reference to racking off into a secondary fermenter after the first few days. Why do you do secondary fermentation?
Second, if you've racked and left behind the yeast sediment, how does fermentation continue anyways?

Thanks for letting me waste your time

ckbryant
06-19-2010, 04:40 PM
I really dislike the term "secondary fermentation," although I understand it's in common use. To me, a secondary fermentation would result from the addition of new food sources (such as bottling sugar) or new microorganisms (as in malo-lactic fermentation). Moving to a new container is just racking, and leaving it there is just aging. We have a bad habit of grabbing these fancy-schmancy terms that don't really mean anything.

Most of the reasons for racking mead have nothing to do with fermentation at all--you rack mead to get it off the lees and minimize the chance of off-flavors developing from the dying and dead yeast, and to help the mead clear before you bottle it.

Mead, unlike beer, has to do a lot of clearing. Most guides suggest racking at the end of fermentation, and then every two to three months until you stop seeing a substantial sediment at the bottom of the fermenter. Then you're ready to bottle.

You wait until the fermentation--the "primary" fermentation, if you insist--is more or less complete before racking because until it is, you don't want to pull the mead off the lees. In fact, you want to _stir_ the lees back up into the solution so that all the yeast in there gets back to work and eats up your sugar as quickly as possible.

jollycynic
06-19-2010, 04:50 PM
okay, that makes sense to me. Much obliged for the info.

Chevette Girl
06-20-2010, 01:03 AM
I think the reason it's typically broken into "primary" and "secondary" designations is by how active the yeast is and what its needs are... in primary fermentation things are very active (bubbles, foam, etc.) and your yeast needs oxygen and nutrients. They do the bulk of the fermentation (eat most of the sugar) during this stage and then they start settling out into the lees as less bubbling happens to agitate things. Primary fermentation is often done in a big plastic bucket with an airlock, it's easier to get in and out if you've got a bag of fruit in there, easier to oxygenate, easier to stir when you're adding nutrients, and easier to clean out any scum left behind from a foamy fermentation. You want to keep the lees suspended till it's mostly done its job, which can be anything from a couple days to a couple weeks, depending on what you're fermenting and how happy your yeast is.

Generally you rack into a secondary fermenter because you no longer have to worry about having extra headspace for active fermentation, and you want to limit its exposure to oxygen and get it off the lees as ckbryant mentioned. Generally you want to use a glass carboy so you can see what's settling out while the yeast that are still suspended (you can't see them but they're there, trust me!) finish the remaining sugar... unless you left it till it had a specific gravity at 0.990, there will still be fermentation going on, it's just trailing off instead of getting started or going whole-hog.

The NewBee Guide has some good explanations on fermentation stages adn when to add which nutrients, that kind of thing, really good references in there, highly recommended reading, and if you still have questions about specific topics, the old-timers around here should be able to set you straight! :)

Happy brewing, before long you'll be looking at everything in the grocery store, thinking, "Hey, I wonder if I can make wine/mead with that?" ... at which point, welcome to the club!! :)

fatbloke
06-20-2010, 03:35 AM
@jollycynic

You don't have to do a racking to an additional/different fermenter if you don't want to.

It's often done, particularly as mentioned here at gotmead, because a lot of people will ferment on fruit or fruit pulp.

You can get off flavours from that.

Also, because when you're in the early stages of fermentation, you'll have noticed that a lot of people will also do staged nutrient additions (to match YANC and gravity levels etc). They'll also aerate the must in the early stages.

Now aeration and staged nutrient additions will often release a huge amount of CO2 and cause the must to foam like hell.

If you've used a carboy/demi-john fermenter, then you'll also probably have read (here at gotmead) about "mead fountains". Damn they can be messy.

So it's common for people to make a 5 gallon batch in a 6 gallon fermenter to start with, as soon as the ferment is underway, the O2 in the head space is discharged through the airlock anyway - and the head space also allows for foaming etc during aeration or secondary nutrient additions. Or if you've used a glass carboy/demi-john then in practice, people will often work out (with the mead calculator) what the likely gravity will be with X amount of honey and Y amount of water (they'll still take gravity readings though) but they'll then mix the must with X amount of honey and a smaller Z amount of water - leaving head space for foaming.

Then when the gravity has got down to whatever figure is decided on, they will top it up to reduce head space and airlock the must to finish it's fermentation (don't forget there's a direct correlation between the honey and water - and while topping up with water will reduce the gravity/alcohol/etc etc, if you've worked out the honey to water ratio correctly at the start you'd still end up with the required/expected % ABV in the finished ferment).

Or they will rack it from the first fermenter to the second one taking it off the lees at that point.....

Ergo, you can still just make a batch up in a carboy/demi-john and not rack it, just "manage" it until you've reached the 2/3rds or 1/2 sugar break and then just top up and leave it.... i.e. no real distinction between primary or secondary fermentation....

Dunno if that helps any.......

regards

fatbloke

p.s. Oh and just because you'd have racked from a primary fermenter to a secondary, leaving behind some lees and then topping up the secondary, that doesn't mean that you've removed all the yeast by any means. To remove all yeast cells from a finished batch, often requires a filter of something like 0.25 microns in size (sometimes called a "sterile" filter). Of course, it's not necessary to have that kind of kit, just do pretty much the same thing with sulphite, sorbate and racking to get the finished product off the lees and cleared.......

Chevette Girl
06-20-2010, 12:21 PM
True enough, you don't HAVE to rack, as an example, one of my own recipes for maple mead - shove everything into a jug, shake the hell out of it, airlock it and leave it for a year... but I have to leave enough headspace for the initial foaming or else it makes a mess of the airlock (as I learned the first time). If the yeast isn't as happy as it could be (as in the case with my recipe, they don't get enough oxygen and the acidity's probably too high), the lees production is minimal and the alcohol conversion is slow.

Medsen Fey
06-21-2010, 10:04 AM
I really dislike the term "secondary fermentation," although I understand it's in common use... We have a bad habit of grabbing these fancy-schmancy terms that don't really mean anything.


Hey, I like my fancy-schmancy! ;D
But in reality what I use is not a secondary fermentation (unless I'm bottle conditioning something or having MLF). Instead, what I use is a secondary "fermenter." My primary fermenter is usually a large plastic container with a lid that doesn't seal, and when fermentation is complete (or nearly so depending on the recipe), I will rack into a "secondary fermenter" that is airtight. So when I use the term primary and secondary, I am referring to the container not the process (generally speaking - but I also get sloppy with my semantics sometimes).

The reasons for racking are well outlined above.

Welcome to GotMead jollycynic!

ckbryant
06-21-2010, 11:00 PM
Well, I like a little fancy-schmancy myself, truth be told. Who doesn't take pride in knowing the difference between a morat and a metheglin? Obviously, I don't dispute your terminology in the slightest--but a secondary fermenter does not necessarily imply a secondary fermentation (or vice versa).

AToE
06-22-2010, 01:56 AM
I don't even think in terms of "fermentors", it's just primary - where fermentation happens, and plain old secondary, tertiary etc. I dropped the other terms pretty much as soon as I started, they only make sense if you're looking at some long tortured ferment!