Sourness in Brett Beers

Why do some brett beers get sour, and others don't?

I've used Brett B, C, and L in various beers with varying results.

For example in my Orval clone I pitched Brett L with no sourness after one year. The same yeast in a belgian dark is sour after 6 months.

What determines sourness vs funkiness?

Depends on a whole lot of things, including wort sugar composition, what strain of Brett L, what other yeasts, exposure to oxygen, process, etc.

from what i understand brett doesn't make beers sour, it makes them funky. sourness comes from pedio and lacto.

Brett can certainly sour a beer. Brett L is known for is pie cherry sourness.

Oxygen exposure to Brett can cause a acetic acid and lactic acid in small amounts.

i've read about acetic, but lactic is new to me. anyone have links to the science? the compounds produced during fermentation should be pretty well known. i'd really like to know.
in my experience, you get funky and or fruity from brett, sourness (not to be confused with fruitiness) comes from lacto/pedio. i've had plenty of old brett beers with zero sourness.

Check out The Brettanomyces Masters Project

I have. In his data, I didn't see anything about sour compounds, (unless i'm missing something) just acids like acetic, etc.

For instance...
"Compound Analysis:

Headspace Gas Chromatography – FID
Acetaldehyde
Ethyl Acetate
Ethyl Lactate
Isobutyl Acetate
Ethyl Butyrate
Isoamyl Acetate
Ethyl Caproate
Ethyl Caprylate
n-Propanol
Isobutanol
2-Methylbutanol
3-Methylbutanol"

Ive had a few beers from the guy who wrote the brett masters proj (crooked stave brewing) there can be a slight tartness from brett, but nothing intense. Ive noticed it in all brett beers more than sach/brett blends. No insight on what causes this though.

I think Chad talked about it during the VT Brewers Conference. I might have just read over something fast.

killsurfcity said:

I have. In his data, I didn't see anything about sour compounds, (unless i'm missing something) just acids like acetic, etc.

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It's completely possible to brew an all-Brett beer with no sourness, but under the right conditions (especially a glucose-rich wort with the levels of oxygen you'd get in a plastic bucket for 6 months) it will produce enough acetic and lactic acid that, especially when combined with high levels of other byproducts such as acetaldehyde that can result from these fermentation conditions, will taste sour.

indigi said:

It's completely possible to brew an all-Brett beer with no sourness, but under the right conditions (especially a glucose-rich wort with the levels of oxygen you'd get in a plastic bucket for 6 months) it will produce enough acetic and lactic acid that, especially when combined with high levels of other byproducts such as acetaldehyde that can result from these fermentation conditions, will taste sour.

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Who leaves 'All-Brett' beers 6 months. Mine are usually in the bottle in 10 to 12 weeks. I've seen it written that should take the same time as a regular sacc beer, but my experience is that the fermentation continues at a slow pace when it is near the end, and takes a while to clear.

I don't detect any sourness in my All-Brett beers. I use Brett-B, and ferment in glass with a regular airlock.

indigi said:

It's completely possible to brew an all-Brett beer with no sourness, but under the right conditions (especially a glucose-rich wort with the levels of oxygen you'd get in a plastic bucket for 6 months) it will produce enough acetic and lactic acid that, especially when combined with high levels of other byproducts such as acetaldehyde that can result from these fermentation conditions, will taste sour.

Click to expand...

Brett can produce acetic acid, it doesnt produce lactic acid

eventhen acetic acid isnt very common, most often whats really going on (especially in the case of WL brett c) is that there is lactic bacteria that are responsible for the sourness.

The Pie cherry sourness of brett L, while Ive seen it talked about Ive never personally tasted it or gotten it to do that for me. I have had it give off a great cherry nose, but no taste.

It is well established in the wine world that members of the Brettanomyces/Dekkera family certainly are acidogenic in certain conditions, sometimes significantly so. You can glance over several references on the topic here: +acid +(Dekkera OR Brettanomyces) - Google Scholar.

In the beer world, I'm not sure we really know what are the conditions the yield acidogenicity. However, I've certainly had some Brett-containing beers turn mildy to moderately sour without evidence of bacterial contamination (I have access to a lab with standard microbiology reagents and equipment). Remember, it is only fairly recent that all-Brett beers were made. Previously, most Brett-containing beers contained a mixture of organisms. Many assumed that because the classic acidogenic bacteria of the Lactobacillaceae family were found in those mixtures that they were the sole agents responsible for acidity. This appears not to be the case.