I never had a real interest in sour beers. There were a few I had tried but decided they weren’t really my thing. And then one day I read about a style of beer called Berlinner Weisse. It can be brewed and soured many different ways. The souring method I read about was called a Sour Mash. The appeal of a sour mash, to me, was containing any infection in the mash tun, and killing the bacteria during the boil. That way you don’t need to worry about isolating sour beer equipment and whatnot. This is my second batch of the Berlinner Weisse and I decided to document the sour mash process for you.
A sour mash is done by cooling your mash down to an acceptable temperature for lactobacillus bacteria to grow and sour the wort. You could buy a lacto culture but it grows naturally on 2-Row, so adding a pound of grain after it has cooled will introduce the bacteria. Using a cooler mash tun, it is easy to keep the temperature for long periods of time. The sour mash is done when you decide it is sour enough. Every 8 hours you will need to taste the wort, and add boiling water to bring the temperature back up. I like mine after about 36 hours of souring.
The Recipe: (10 Gallons)
8 lbs 2-Row (+ 1 lb of un-milled 2-Row for the sour mash)
6 lbs White Wheat Malt
2 oz Hallertau (15 minutes)
Mash thicker than normal at ~154* for 60 minutes (0.88 quarts of strike water per lb of grain)
Cool your mash to under 120* and add 1 lb of un-milled 2-Row, introducing the bacteria. Keep temperatures between 95* and 115*. The warmer it is, the faster it will sour. Flush out any O2 with CO2 whenever disturbing the sour mash. Every 8 hours or so, you will need to add boiling water to keep your temperature within range. This is the reason for mashing thick, because you will be adding more water. You must taste the wort as it sours to make sure you’ve got it as sour as you want.
Fifteen minute boil. The boil is mainly to kill the bacteria. Add a little hops just to balance things. BJCP calls for 3 – 8 IBUs.
Ferment with a neutral ale yeast. I use Nottingham.
My Process in Photos:
For a sour mash, you want a nice THICK mash. I used roughly 0.88 quarts per pound of grain, which gave me exactly 3 gallons of strike water. With that small amount of hot water, I was able to heat it on the stove top, which is really nice, having kids and all.
It is important to flush out any O2 in the mash tun with CO2. Lactobacillus works without O2, so it will sour just fine. The lack of O2 will prevent other bugs from taking hold and doing any souring of their own. I remove the quick disconnect from a CO2 keg line and flush it for 15 seconds each time I disturb the sour mash. By giving the lacto control of the show, you will prevent any terrible smells you may have heard of during a sour mash. It smells of creamed corn, or cooked vegetables, not like vomit. If you have bad smells, that is a good sign that other bacteria is working. The CO2 is important.
Check the temperature every 8 hours or so. Add boiling water to bring it up to temperature. I tried to keep mine around 105*. After 8 hours, it would usually drop to about 95*. A quart and a half of boiling water would usually bring it back up to 105*
You also need to taste it and see how the souring is coming along. The wort is warm, brown, has chunks of grain floating in it, and smells like sour cooked corn, but it’s not too bad. I promise you it won’t kill you!
After roughly 36 hours, the mash was as sour as I wanted. At this point, I spargued as usual and boiled for 15 minutes with 2 oz of Hallertau hops to give me around 5 IBUs. The problem with waiting for the bacteria to do their thing is, you may be boiling your wort on a Sunday morning right after breakfast while still enjoying your coffee and in your pajama pants.
Sour Mashing was an interesting technique I read about one day that I used to make one of the more interesting and delicious beers I have made to date. Berlinner Weisse is definitely an under appreciated beer and definitely a crowd pleaser!