Brettanomyces question

[Dougal]

Quick question everyone. I'm doing a wee experiment tonight with some Orval dregs. I have enough spare wort from a Rochefort 8 clone I made recently to fill a 5 litre demijohn with 1.050 (diluted) wort.

Shall I just pitch the dregs, or should I put in a small pitch of yeast slurry to stave off infection while the Brettanomyces multiplies? I read that you get the most pronounced Brett flavour from underpitching and under-oxygenating.  

Any ideas?

[Liam Callaghan]

I can't answer your question Dougal and with 2 hours experience cultivating yeast I can't offer any suggestions either but I am interested in how you got on :)

[Dougal]

In the end I pitched a small amount of 1762 and the Orval dregs together- they can fight it out. I'll ferment it on the cool side so the 1762 drops out early and leaves some sugars, then warm it up once the Brett is established.

Shame I only have 4.5 litres. Time to plan a bigger batch...

[Kelly Ryan]

The Brettanomyces will be pretty knackered and there at very low levels, but may eventually grow up to the point where you'll get Brett characteristics. Orval use this yeast for secondary fermentation (in a mixed culture) and actually use their primary yeast strain for bottle refermentation, hence the slow development of Brett notes as the bottles age.

I would ferment with yeast slurry for a few days to drop pH and get some alcohol going to act as protection, then introduce the Brett. Prior to introduction, the actively fermenting beer would actually benefit from oxygenation (up to around 6 mg/L) as this is what Brett likes if you want to boost the acidity. I've even read that constant micro-oxygenation throughout maturation helps boost sourness. Will likely be 6 months minimum until you get any pronounced Brett character.

I did a 100% B.lambicus ferment a few months back and it still has zero of the Brett notes that we all know and love. It is a time game...  

[denimglen]

I did a 100% B.lambicus ferment a few months back and it still has zero of the Brett notes that we all know and love. It is a time game...  

That's interesting.  I've just tapped the keg of my 100% brett L beer and it has some great brett character.  That pie-cherry that's quoted in the Wyeast description and some hay-y, barnyard-y notes.  Although I did acidify my wort quite a bit before fermentation which may have helped.

[Kelly Ryan]

Nice, yeah, mine is coming across quite Belgian in character, very Belgian Golden Ale, almost like a Maredsous 6. Do get a little cherry, but in terms of fruit notes, it's more pineapple. My grist was 50:50 Maris Otter and Abbey malt, so it may also be that the malt character is dominant. Ageing it at ambient to try and speed up Brett activity, still nothing.

What AbV was yours? Did you do any oxygenation throughout ferment or maturation? How long was your ferment time? 

[denimglen]

At work at the moment and running off (a not very good) memory haha.

Mine had a good portion of wheat malt in it, so ferulic acid may have played a part.  The rest of the grist was Weyermann pils, with some acidulated malt - about 3% I think.

Pre-ferment I added some lactic acid, I can't remember the amount.  Initial plan was to use all acidulated malt but had some dramas with that on brew day...

Beer is very tart, wouldn't say it is sour as such though.  The majority of this is from the lactic I'd say as I'm not really picking up any acetic notes.

Abv is around 5.0%.

No intentional oxygenation.  It was fermented and aged in a PET Better Bottle with a silicone carboy cap, so likely there was a little oxygen transfer.

Primary ferment was about 3 weeks at around 20 - 22C.  I then lagered it for about 2 -3 weeks - besides not having a keg to put it in my thinking was that kept cold the brett was less likely to clean up any flavour compounds it had formed.  It smelt good after that 3 weeks, didn't get a chance to taste it though.

Pitching rate was Wyeast pack into a ~1000mL starter for a 20L batch - the same as I would of used in an ale.

Sorry for all the 'about's and 'I think's, will repost later this arvo when I have some notes infront of me.

[Dougal]

Thanks Kelly,

That's really interesting and most useful. I'd just found this paper too, so I see what you mean about oxygenation and acidity. Would stepping up a starter culture from the Orval dregs amplify the Brett enough to get it to useful levels? What wort conditions would favour Brett growth over the bottling strain? 

Cheers

[Kelly Ryan]

Hmmm, hard to say unless you can pull out a haemocytometer and do a yeast count. I think I recall Brett cells been a little more elongated than Saccharomyces, but this probably will be rule of thumb only. I'm guessing that because the Saccharomyces is a faster grower, it would be the dominant competitor in the starter, with the Brett in the background ready to chew up all those dextrins later in the piece. I'm not well versed on wort conditions and how they could be modified to improve Brett growth in a mixed culture though... Best bet may be asking around and seeing if anyone has got any 100% Brett ferment brews in bottle that you could use to get a pure strain??

[Kelly Ryan]

The other option would be to make up a simple wort agar and look at the colony morphology, though will probably work out easier just to buy a culture from Wyeast :) 

[denimglen]

There may be selective medias for brett too.  Prepoured WLN agar plates from FortRichard  Laboratories in AK are about $25.00 for 20 plates, could be worth asking them - http://www.fortrichard.co.nz/

[Dougal]

Thanks.

It must be easier to get the Wyeast culture, but I HAVE been looking for an excuse to try plate culturing...