Tuesday Beer Trivia: Sour Beers

The following explanations are taken from Sour Beers by Michael Tonsmeire.

Question 1: 

In the past, many breweries in Berlin didn’t boil their wort, which allowed wild Lactobacillus living on the malt to survive into the fermenter. Modern breweries maintain cultures of Lactobacillus, but Professor Briem’s 1809 Berliner Style Weisse uses the strain that was originally isolated from the malt. Modern German breweries typically pitch Lactobacillus into wort along with ale yeast, or the wort is divided and fermented with Lactobacillus and brewer’s yeast separately.

Question 2: 

This is one of the biggest misconceptions about brewing with fruit beer. Many people assume that the added sugar of the fruit will contribute to a higher final gravity, but in practice, the water in the fruit can dilute both the alcohol and the sugar already in the beer.

Question 3: 

The microbes found in bottle dregs are often much hardier and faster, and they produce a greater range of by-products than their domesticated counterparts produced from larger yeast labs. Fresh bottles of beer with low alcohol content are the best for harvesting dregs. Check the bottle date, as bottles older than two years may not harbor living microbes.

Question 4: 

These malts provide complexity to the malt character of the beer. When mashed, these malts do not lower the fermentability to a noticeable effect. While the inclusion of caramel and crystal malts is not an effective way to add fermentable sugars specifically for non-Saccharomyces microbes, some of these specialty malts’ perceived sweetness will remain even after the mixed fermentation, helping balance alcohol and acidity.

Question 5: 

Brettanomyces is a “wild” yeast commonly used in sour beer production. It is a genus of yeast, not a bacterium like many believe. The primary role Brettanomyces plays in fermentation of sour beers is to ferment dextrins, during which time it produces a wide range of characteristic esters and phenols. Brettanomyces is also frequently used alongside Pediococcus, since Brett can clean up certain byproducts of Pedio metabolism like diacetyl.