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Acid in beer

Braden Jackman

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How did it get in my beer?

Deliberate

Cross contamination

Poor cleaning or sanitisation

Transfer or packaging

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Acid forming

bacteria and yeast

Lactic acid forming bacteria

Found in yoghurt, sour lollies (can also use citric), tart but generally pleasant

Pediococcus - identified in beer with ropiness, hop tolerant, slow production of acid, produces diacetyl

Lactobacillus - tart acid, fast producer, not hop tolerant.

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Acid forming

bacteria and yeast

Acetic acid�Most commonly found in vinegar. Harsh acid

Brettanomyces - Most common spoilage microbe, can break down diacetyl produced by Pediococcus.�Traits include horse blanket, cherry pie, pineapple, tropical fruit, clove, band-aid, produces alcohol.

Acetobacter - Used in the production of vinegar, acetic acid�Generally considered a harsh acid on the palate compared with lactic.

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What to do if infected or when to use deliberately?

You can do nothing - let it thrive and see what it does.�Add other microbes to add complexity to existing beers. �Brewing faults - Use Brettanomyces to reduce diacetyl.

Eradication�Scrupulous cleaning and sanitation required.�Replace equipment if source is identified.

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Yeast/microbe blends

Blended for a specific purpose/style

Ready to use

Convenience

Predictable results

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Strains commercially available

Whitelabs and Wyeast are readily available in blends or single strains

Can also harvest microbes from commercial beers.

There are a lot being produced locally at present and are unlikely to be pasturised.

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References

Milk The Funk - http://www.milkthefunk.com/

The Mad Fermentationist - https://www.themadfermentationist.com/

American Sour Beers - http://www.bookdepository.com/book/9781938469114/?a_aid=melbournebrewers&chan=direct (club affiliate link)