Image Courtesy: Winemag
Acidulated (AKA Sauer malt), as the name suggests; is a type of malt that contains small amount of lactic acid which is naturally formed during specific malting process.
Acidulated malt is most commonly used in small amounts (1-5%) to reduce the pH of the wort or mash. It can add complexity and slight tartness that helps highlight certain hop flavors. Also, style specifics such as Gose, sour Belgian ales and German lagers can benefit from the tartness it provides. The mysterious sourness in Guinness Stout is also contributed by acidulated malt.
Also, in some paler styles dropping the mash pH during mashing becomes difficult due to low tannic content of the malts involved. Maintaining a mash pH in the commonly accepted optimal range of 5.2 to 5.6 encourages efficient conversion of starch into fermentable sugar, prevents the extraction of excess tannins that lead to a harsh hop bitterness, and generally lead to a better tasting finished beer. This is where acidulated malt comes in handy.
Can you make Acidulated malt at home?
While preparation of most other types of malt requires precise kilning, drying and/or toasting, making Acidulated malt is a relatively easier process. Barley grains naturally contain lactic acid producing bacteria. All it needs is some moisture and warmth to get active and start converting starches into lactic acid. Let’s see how we can make it at home.
Many strains of lactobacilli are omnipresent in barley
All you need is a base malt (pilsner or pale ale is usually prefered) since in other malts lactobacillus are most likely destroyed due to high temperature kilning/toasting.
1. Take preferred amount of malt and mill it coarsely as you would before mashing. You can also avoid this step, but breaking the grain allows water to penetrate the grain slightly quicker. Add them to a Ziplock bag.
2. Take as much water as the grains in weight and heat it to 45°C.
3. Add water to the Ziplock and seal the bag. This will remove the risk of any mold formation on grains.
4. Leave it in the bag for 24 to 36 hours. Depending on room temperature the malt should acidify enough for brewing purpose.
5. This malt then can be added directly to your brew mash or can be dried under sun or in an oven at the lowest setting until the weight of the grain reduces back to original state.
Make sure not to heat up malt over 40°C otherwise you could activate various amylase enzymes present in malt and end up with a sweet and sour caramel malt.
Tossing malt in oven for slow drying
6. In case of planning to dry the malt for further usage I’d suggest not milling it. That way you can preserve the grain for much long.
That’s all.
Happy Homebrewing!