Native yeast test

[greenxpaddy]

I've been looking at my tired raspberry bushes with squidgy raspberries ready to drop off at any moment. If ever was the right time to try and harvest my native yeasts now has to be the right time in Autumn. All summer for wasps to spread yeast from plant to plant and time for the yeast to multiply on the raspberries as they slightly mush. Not so late as a deep frost will have got at the yeasts and killed them.

Here's the plan.

In a small glass I'm going to mush some raspberries into 10ml of boiled cooled shaken wort. Standard starter process. Shake regularly . Leave for a day or two. Step up to 30ml, 2 days, step up to 100ml, Step up to 400ml stirplate,. At 400ml leave to ferment out. Chill, decant off. ACID WASH to remove bacteria and mould spores. Step up to Pitch into 3L stirplate.

Ready for a 15L pitch (going strong)

Aerated wort leftover from another brewlength will be used to pitch this, beefed up with some sugar and Amber LME. The ferment will be carried out in a stainless pan away from my brewery (spare bedroom) and the pan can be steam cleaned after.

I'm thinking of a strong wort with Belgian characteristics to withstand the funk.

Thoughts?

[jimp2003]

Sounds like a plan - What's the worst that could happen?

A while back I was talking to the brewer of Red Brewery who are based in Huntingdonshire and he was going to try something similar with fruit to give a beer a funky character.

I would be really interested in hearing how you get on.

[greenxpaddy]

Well, seems to be some fermentation even at 10ml..... Stepped to 30ml. Pectin in the 3 raspberries nearly set the 10ml!

[greenxpaddy]

Definitely reacting like a normal step up from plate so looking hopeful. Will step up to 100ml later.

[greenxpaddy]

100ml has been on stirplate 36hrs. Smells like nail varnish remover. I suspect there is too little yeast in there at the moment, so next step up is x5 rather than x 10.

[Capn Ahab]

Nail varnish remover smell is ethyl acetate; often produced by brettanomyces.

I've tried to capture usable wild yeasts and results have been mixed. Well,to be more accurate, I've had some accidental infections that tasted good, but seeing as I don't have a lab (or know the first thing about pure culture techniques) it has not been possible to isolate the yeast, and when I've tried reusing the slurry it has never gone well, most likely because it is a mix of yeasts, and there's no way of controlling which one will dominate without isolating the good one. And that, without even considering the necessary equipment and techniques, is a lengthy job of trial and error.

Given that there are literally thousands of stains of brett (compared to about 500 of saccharomyces, it's very much a hot and miss game.

Good luck to ya!

[greenxpaddy]

Thank you. I am encouraged that I have cultured wild yeast at least! Though I wouldn't want my beer to smell like that!

[greenxpaddy]

this is how the starter looks at 800ml after numerous steps

[Subsonic]

ethyl acetate is also a classic distillers smell. Often the fruit fly's come in over the distillation column as the acetate washes out. I've seen it many times. Strange you got that, but interesting. Sub

[greenxpaddy]

I did a massive over pitch of the wild yeast in 1.5l and it behaved like saccharomyces. Same attenuation and same duration. There is a little information to this respect online. 100per cent Brett ferments are not as wild as you might think....

[Belter]

Wild brews is a good one to read if you haven't already. Talks about how Brettanomyces acts in a very similar way in an 100% Bret fermentation like you've described.

[greenxpaddy]

If you think Brett gives off bad odours when its a minority yeast in a mainly saccharomyces environment you should see what happens when you get lager yeast in your normal brews. Rotten egg. Unbelievable. That's the last time I rack/bottle ale after racking/bottling lager using the same kit.