Tuesday Beer Trivia: Sour Beer Bugs

Put your knowledge of wild fermentation to the test in this week’s Tuesday Beer Trivia quiz.

Sugary wort is turned into beer by yeast who conduct the process of fermentation. Sour beers, however, take a special teams of yeast and/or bacteria (otherwise known as “bugs”) to achieve that signature funk that beer drinkers are going crazy for.

Being able to tame these beer bugs is a skill to be admired, so never take a sip of great sour beer for granted!

After you take the Beer Trivia quiz below, scroll down to “Beer Trivia Answer Explanations” section to learn more about wild fermentation.

Beer Trivia Answer Explanations

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Get a crash course on wild beer yeast and bacteria: Sour Microbes: Yeast and Bacteria Explained.

Question 1: Saccharomyces, commonly known as brewer’s yeast, is the single genus of yeast responsible for fermenting all clean beers. Although it is usually used in sour fermentation in conjunction with other yeast and bacteria, it does not typically lend sour beer’s signature funky characters, though some Belgian yeasts may trick you into thinking so.

Question 2: Brettanomyces, often referred to simply as “Brett,” is a genus of yeast, not bacteria as far too many brewers falsely believe. It is the principal wild yeast used in sour beer production.

Question 3: Lactic acid is the primary acid in sour beers, along with carbonic acid from dissolved carbon dioxide, and is produced by lactic acid bacteria (specifically Pediococcus and Lactobacillus). It is mellow and tangy at low levels, but can be quite lip-puckeringly sharp at higher concentrations.

Question 4: Brett also doesn’t contribute much to the acidity of sour beers, either. Acid production is the responsibility of bacteria. The only exception is when there is a large amount of oxygen available, which causes brett to produce acetic acid creating a vinegar-like sourness.

Question 5: The drawback to acidifying with Pediococcus (pedio) is that most strains produce concentrations of diacetyl above the taste threshold. Unlike brewer’s yeast, pedio doesn’t reduce diacetyl by converting it to less-flavorful by-products. Instead, it leaves the buttery popcorn flavor behind. A good remedy is to include brett in beers that are pitched with pedio, so it can eliminate diacetyl. This takes time, so be patient if your beer tastes like movie theater popcorn when it’s young.


Homebrewers Association
Homebrewers Association