BIAB question

[homrocks]

So I have been doing research trying to find an answer to this question, but I haven't found anything. So with the BIAB method, is there a difference in product with fermenting with the bag or without the bag? From what I can tell, most people say that you mash with the bag, but when transferring the wash to the fermenter, you should take the bag out, since the sugar has already been converted and the sugar is now in the wash. I would have thought to keep the bag in the fermenter with the wash so that it all ferments together. does that make sense, or do I need to reask my question? Thanks!

[jonnys_spirit]

Depends on whether you want to ferment on or off grain. I ferment on-grain normally and squeeze it when complete. I prefer to maximize extraction and feel like that helps.

Others ferment off grain and sparge like a beer.

Commercially it’s also done both ways.

Cheers!
-jonny

[greggn]

So I have been doing research trying to find an answer to this question, but I haven't found anything.

The answers are out there but you need to filter them to your individual needs. Some ferment on-grain, some off-grain. What works for me may not work for you. I ferment off-grain because that works within my infrastructure ... but that's me.

It's a simple question but a complex answer.

[zapata]

For malt I ferment off grain, so I pull the bag. For small batches at least, I use an allinone with a malt pipe and bag. Easy peasy, traditional, plus you can make a sugar head with the grains to keep your mitts off the all grain until it's aged proper.
Everything else I ferment and run on grain. Before I could run on grain I tried everything under the sun, including fermenting in a BIAB and pulling it post ferment. Like everything else under the sun, it's workable, but falls far short of the convenience of running grain in.

[SaltyStaves]

If its a nylon bag, then I'd imagine it would shorten its life leaving it in an acidic environment for days/weeks. I'm sure you'd get many uses before failure, but it can't be good for it in the long run.

[silverbean]

I thought BIAB was just a cheaper way than getting all the equipment to sparge and strain the grain. If you ferment in the bag wouldn't it restrict the circulation of the grain? When I ferment on the grain I don't use the bag until I siphon off most of the wash to settle then tip what's left into the bag, hang it over a pot for a day to drain then toss out what's left in the bag. Tried squeezing it but after a day hanging there is not much left.

[still_stirrin]

I would be concerned about bacteria growing in the fibers of the sack over time when it is left in the wort/ferment. The fibers would act as a culture medium for all kinds of “wild things”. And if you’re using the bag this way, I also suspect you’re too lazy to properly clean the BIAB sack between uses as well. So, it sounds like a sloppy way to brew.

Sure, you’ll distill the ferment after it’s done, but how do you manage your “boiling bag”? Whatever you allow to grow in the fibers will inoculate the next feeding medium/wort you put it into.
ss

[zapata]

Uhh, how exactly does that logic work? Are people that strain post ferment sloppy and lazy because they might not wash the bag out and it might grow the exact same scary things that a fermented bag would? Does a hankerchief make you sick for years, or does washing things, like, I dunno, make them clean again? I don't want to defend it too much because it's not something so awesome I adopted it as SOP. But considering I've actually done it with absolutely no problems, worrying about contamination would be super low on my list. Wash your bag when you're done. Don't use if it grows fur.

Could it wear the bag out eventually? Maybe, I didn't do it a whole lot but didn't notice. Did it restrict the grains from moving about in some way? Not that I could tell. Is it awesome? Nope. But it saves having to transfer the mash an extra time, and yes, I'm lazy.

[Bee]

How are you guys that ferment on-grain separating the grain from the wash before you distill?

Last batch I fermented on-grain with the grain in a paint straining bag from the hardware store. Cheap, so who cares if it rips after the first use?

[still_stirrin]

Personally, I don’t ferment “on the grain”. I lauter which certainly is challenging because corn is a “beeeyatch!” to sparge. But, post ferment, I can simply rack off the trub. This is what my fermenters look like (this bourbon is 6 days post-mash):

5 grain bourbon

As you can see, there is some settlement as the distiller’s beer settles. It will clear better in the next week before I rack it to the boiler to strip (I will wait another week for it before stripping).

This is the last ferment as it finished and is ready to strip:

5 grain bourbon

See how it has cleared?

Would I ferment in bags in order to ferment “on the grain”? No, I would use a strainer to scoop out the grains (post ferment) and squeeze those. I would let the yeast help with settlement as the sugars are consumed. Sure, the process would be messy. But, if you’re trying to squeeze out every bit of alcohol, then you’ve got to work at it.

I prefer my process...you may favor yours. Que sera, sera.
ss

[OldSmitty]

ss,

Do you batch sparge or fly sparge?

What do you use as the filter to strain out the grain as you run off?

[still_stirrin]

Do you batch sparge or fly sparge?
What do you use as the filter to strain out the grain as you run off?

I “fly sparge”.

I have a sparge arm that connects to the hot liquor (hot water) tank with a small pump, so I can regulate the flow rate to match the wort runoff. I lauter in the mash tun, so the grain bed becomes the filter. My mash tun has a stainless steel false bottom with a drain grid system to help drain the liquid (sometimes, a thin slurry) and I usually recirculate back into the mash tun to help “set the bed”, or create a graduated filter bed in the grains.

The wort runoff is also pumped from a “grant” so it doesn’t suck the grain bed down. Again, a slow runoff (and sparge) is key to a high gravity extraction. But a high corn proportion and rye malt can really make runoff slow, ie - some may not have the patience to wait for it.

History/experience:
I brewed beer in the local brewpub several years ago, so building brewing equipment to emulate that process came very naturally. Adding to my skillset, I am a senior mechanical design engineer and I worked in oil and gas production equipment design for several years. And I worked for a plumbing contractor while I was in engineering school, so that helped with my copper working skills as well. And my foundation was in the dairy business as my father was a dairy farmer. It all adds up to give me the “tools” necessary for this hobby.

And I am an AHA certified beer judge, so that helps me with my judging and “making cuts” skills as well. Over qualified...probably not, but it certainly has helped me in this hobby.
ss