Lambic & headspace

[molc]

So, I'm going to do my first lambic and I'm going the extract route, simply as the bugs are the star of the show, so why bother with mashing. Recipe is simply 47% Light DME, 47% Wheat DME, 6% Maltodexterin as bug food, ~7IBU and the yeast bay mélange. Then into the fermentation fridge at 18C (yeast will bring beer upto probably 20, I'm just going to regulate the environment) for 5 days, then moved to the garage to sit in a dark corner for a year at ambient.

I'm going to ferment in a plastic carboy, so I'll need some headspace to not have a blowoff, but once fermentation has subsided, I want to topup to reduce oxygen pickup. I was thinking of keeping back a portion of the unfermented wort in a sanatized, covered container for 5 days, then adding it to the carboy for the topup.

Question:  Anything think leaving unfermented wort like that for a few days is risky? Should I maybe put a little yeast into it to also ferment at the same time to keep it safe? Perhaps leaving it for those couple of days could even be beneficial for a lambic!

Answers on a postcard

[Dr Jacoby]

Why not ferment the side portion of beer with some brewer's yeast (and bugs too if you want)? Less risk of an unwanted infection.

If you're using a better bottle carboy I wouldn't worry about oxygen pickup by the way. It's the other standard plastic fermenting buckets that would cause problems.

[molc]

Yup, I think I answered my own question about fermenting the side portion - I'll throw it and some US-05 into a demi and let it ferment away before the topup.

I'm using one of the older PET bottles that has the stupid tap on it. Should be perfect and it's slightly too small to use for stand batches, so time to sour it up. That tap will give me a great bug colony over the years >

[Dr Jacoby]

The tap will be handy for samples!

Lob some oak cubes in there and you can use them to innoculate future batches.

[Simon_]

Yup, I think I answered my own question about fermenting the side portion - I'll throw it and some US-05 into a demi and let it ferment away before the topup.

I'm using one of the older PET bottles that has the stupid tap on it. Should be perfect and it's slightly too small to use for stand batches, so time to sour it up. That tap will give me a great bug colony over the years >

If it's extract why don't you just cook up the extra portion when you intend to top up?

I had the same idea a few months back for a sour (avoiding blowoff and topping up later). In the end someone convinced me it wouldn't make much difference, keeping airlocks topped up was more important. It hasn't gotten a pellicle after 20 weeks so I take that as a sign that no O2 is getting in.

[molc]

Yeah that's a good idea as well. I think fermenting both batches at the same time is easier, simply as then it won't begin another fermentation when the headspace is filled. The only reason I'm trying to fill it is the fermenter is only 19L, so I want to cram in as much as possible since it will be souring for a year

Also, the reason to use a PET carboy is actually to get a small amount of oxygen, similar to the level a wood barrel would give. As you said though, the airlock still needs to keep oxygen out.

[Simon_]

Sweet. What bugs?

[molc]

Sweet. What bugs?

The Yeast Bay Mélange. Sounds tasty:

"If you dig using a diverse array of unique organisms to create balanced sour beers, this delightful medley of microbes is sure to please!
Mélange is our most varied mix of fermentative organisms, intended for use in the production of sour beers in which a balance of funk and sourness is desired. This blend contains two Saccharomyces cerevisiae isolates, Saccharomyces fermentati, five Brettanomyces isolates, Lactobacillus brevis, Lactobacillus delbreuckii and Pediococcus damnosus. 
If you want acidity quickly, we recommend keeping the IBU low (0-5 IBU), starting with a fermentation temperature of 70-72 ºF for the first few days and then raising the temperature to 75-80 ºF to encourage development of sourness (Lactobacillus, Pediococcus). For a slower developing beer that exhibits a rounded balance of funk (Brettanomyces) and sourness we recommend ~5-10 IBU, mashing on the high end, fermenting at 68 ºF and holding at that temperature for an extended period of time.
Approximately 29 bilion cells/vial.

Temperature: 68 - 78 ºF
Attenuation: 85%+
Flocculation:  Medium-Low"

I'm going to get the IBU's to around 7 and do the slower version and try to get a more rounded sour. We'll see in a year

[Dr Jacoby]

I'm hearing great things about the yeast bay strains. Looking forward to working my way through them!

[molc]

Yeah the reviews online were pretty good.

Found myself craving some funk last weekend. Two 330ml bottles of bog standard lambic cost me €11, so it was a turning point for me. Even being utterly lazy with this batch by using extract, it's still only costing about €35 to make 20L, with less than a 3 hour brewday. Bargain!

Also, we brewed the NCB barrel sour about a year ago now so I'll starting having some nice young lambics to start blending in a year or two for some geuze, not to mention a kriek and framboise near the end of the summer.

[Dr Jacoby]

Nice. Nothing like a good homebrewed sour.

[nigel_c]

If your gonna age for a year will an extra 2 or 3 hours on a brew day make that much of a difference?

[molc]

If your gonna age for a year will an extra 2 or 3 hours on a brew day make that much of a difference?

Oh no, it's just been ages since I had an extract brew day and it's meant to make almost no difference in a lambic, so I decided to give it a go. Going to do it Sunday, hungover after Brewcon and it just feels like the perfect lazy brewday. Was even tempted to try and do it as a no boil, but I need to boil down the hops a little at least...

Got the idea from the lambic brew network podcast from a few weeks ago.

[nigel_c]

Just stiring.
I've seen recipes that call for up for 3 hour boils for sours.