When is sour beer a good thing and when is it not? Twenty or even 10 years ago, who would have thought so many beer drinkers would welcome sour flavors in their beer. There’s such diversity in sour beers it’s beginning to be difficult to differentiate good sour from bad sour. Sour flavors from acidic compounds are a component of certain styles. Getting a dose of sour flavors in most ales and lagers is a disaster in works. How do you recognize the difference?
There are three main acidic characters common in specialty beers, with a fourth often unrecognized source of acidity.
- Lactic acid
- Acetic acid
- Citric acid
- And a fourth unexpected acidic character.
Lactic acid is a common threat encountered in the brewing and fermentation process. Except for what one might call “specialty beers,” lactic acid production is avoided in most breweries. It’s produced mostly by several strains of lactobacillus bacteria (the same bacteria turns milk into yogurt).
There are other lactic acid producing bacteria such as pediococcus. Bacteria convert sugar into lactic acid and other flavor compounds, including various fruity esters. In specialty beers such as Belgian lambics, sour brown ales or American wild beer natural bacterial fermentation produce a complex mixture of esters and acid. The result is a complex and interesting beer that may improve with age, depending on the balance of other ingredients.
Some brewers fearful of contaminating their brewery with lactobacillus bacteria may still produce specialty beers with lactic character by simply adding pure food additive of pasteurized lactic acid. This contributes acidity, but its character is best described as simply sour, adding no complexity.
Photo right: Belgian lambic have fruit acidity as well as lactic acidity resulting in a balanced sourness. Photo courtesy of Brewers Publications.
Lactic acid is also added to part of the brewing process called mashing for completely different reasons. When water is very hard, containing many minerals, specifically compounds of calcium and/or magnesium, brewers add lactic acid to neutralize the water, making it more suitable for brewing. In Germany by law, brewers cannot add lactic acid. Instead they “sour mash” malted barley at about 100 degrees F to unleash lactobacillus bacteria naturally present on the malt. The bacteria produced natural lactic acid neutralizes the mineralized hard water during the mashing process.
Some beer types that engage lactic acid in their character are Belgian style lambic, gueuze, etc., Belgian sour brown ales, American soured beer specialties (too numerous to count), German-style Gose and some specialty fruit beers.
Next: Sour beer: more on lactic, acetic, citric and another.
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