What is Sour Malt?

What is Sour Malt?

There are many kinds of malt for brewing beer, like light malt, dark malt, burnt malt, wheat malt, sour malt etc. 

Sour malt is often used in adjusting the pH of the mash during brewing. 

Typically brewers use a 1-10% with 2-5% being typical.

Sour malt is also called acidulated malt or saurmalt, it is a base malt that has been processed so that it contains lactic acid. 

Sour malt is a pale malt (color: roughly 3 to 6 EBC/1.7 to 2.8 SRM) that has been subjected to 

a lactic acid fermentation after kilning and a second finishing drying cycle.

The lactic-acid bacteria reside naturally in the malt.

The purpose of acidulated malt is to reduce the pH value of the mash.

The optimum wort pH of most barley-based beers is 5.2, and of most wheat-based beers is 5.0. 

Measurement of the pH values from the mash-in to the finished beer informs the brewer 

if a pH correction is necessary and how much acidulated malt, if any, should be used in the mash.

Proper mash pH helps assure the enzymatic performance on which the brewer relies

 to break down gums, proteins, and starches. 

It also leads to proper wort pH, which affects yeast performance during fermentation 

and the final flavor profile of the resulting beer. 

Every 1% of acidulated malt (by weight) of the total grain bill reduces the mash-pH by 0.1 point. 

In highly alkaline mashes, acidulated malt can make up as much as 10% of the grain bill.

Nowadays, using a sour mash goes way further than just correcting pH. 

It's used to define the sourness in some beers, such as Berliner Weisse, Lambics, Flemish Reds and Browns and Stouts.

So, while you can't buy a beer made only with sour malt, there are plenty that have used it,

 or an equivalent souring technique to produce the sour notes in the beer.