Today I brewed a small batch of something a bit different. I made an attempt of brewing a sour ale / pseudo-lambic. The malt bill was simple, containing 2 kg of pilsner malt and 1 kg of raw wheat. The mashing was however a bit more complicated, as I attempted a turbid mash. The turbid mash results in a starch-rich wort, leaving some food for the pitched bacteria once the yeast has consumed all the simpler sugars. The mash procedure was as follows (12 liters of mash water and 3 kg of grain):

• 2.4 liters of 65C water was added to the grain, resulting in a mash temperature of 45C. The temperature was held for 15 minutes.
• 2.4 liters of 85C water was added to the mash, resulting in a mash temperature of 52C. The temperature was held for 15 minutes.
• 1.6 liters of wort was transferred to an empty kettle, and temperature was raised to 88C.
• 3.6 liters of 100C water was added to the mash, resulting in a mash temperature of 65C. The temperature was held for 15 minutes.
• 3.4 liters of wort was transferred to the kettle already containing wort, and the temperature was again raised to 88C. Total volume in kettle now 5 liters.
• 3.6 liters of 100C water was added to the mash, resulting in a mash temperature of 72C. The temperature was held for 30 minutes.
• The mash tun was drained, and the wort (~7 liters) was transferred to the kettle, and the temperature was again raised to 88C.
• The grains are rinsed with the 88C wort, resulting in a mash-out temperature of 78C. The temperature is held for 20 minutes.
• The wort was transferred to the boil kettle, and the grains were batch sparged with 10 liters of 78C water.
• The sparged wort was then added to the boil kettle, resulting in a pre-boil volume of around 22 liters.

After the mash I boiled the wort for 2.5 hours (in order to reduce the 22 liters of ~1.025 pre-boil wort, into 15 liters of 1.040 post-boil wort) together with 20 grams of old Saaz hops. The hops (2010 harvest) have been in an opened package in the freezer for over a year, so their alpha acid content is presumably below the 3.1% stated on the package. In a sour ale you want to keep the iso-alpha acid concentrations on the low side, since they inhibit the growth of lactic acid bacteria. After the boil I chilled the wort and pitched a pack of Wyeast’s Lambic Blend. I will leave the wort in the fermenter for around 9 to 12 months, after which I will add 2 kg of blueberries and bottle dregs from two bottles of 3 Fonteinen Oude Geuze. I’m expecting to bottle this one in around 12 to 15 months.

I was mashing in my 21 liter kettle and a BIAB-bag (this helped when pulling the liquor from the mash).

The yeast and the hops. Hopefully I haven’t overdone the hopping.

I’m using a glass carboy for fermentation, in order to reduce the amount of oxygen that comes into contact with the wort/beer during the long fermentation.

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