I visited my old KPU brewing classmate, David Dayco, at Container Brewing where he was making a sour wheat beer. This beer is a play on a traditional Berliner Weisse which is a cloudy sour beer that is usually around 3% alcohol by volume. It is a regional variation of the wheat beer style from Northern Germany, dating back to at least the 16th century.
This Berliner Weisse (ish) beer is a light refreshing sour wheat beer. It has a slightly higher % abv than a normal Berliner Weisse which is usually 3.2-3.5% abv. It is flavoured with bitter orange peel, crushed coriander seeds, and blueberry blossom honey. Dave came up with this recipe near the start of the Covid shutdowns, and fittingly named it ‘Be Right Back’.
1. Milling
Their mill is located high up, so Dave has to climb a ladder to get to it. Bags of grain have to be forklifted up to the mill to get milled. For this beer 360kg of grain was used in total. There was 50% pilsner malt and 50% wheat malt. Once milled, the grain moved through the spiral auger and into the grist hopper above the mash tun.
2. Mashing In
At the start of the brew day, Dave rinsed the mash tun out with hot water to warm it up. The water was then flushed down the drain to rinse out all the pipework. Next, he filled the mash tun with hot liquor from the hot liquor tank (HLT). He was aiming for a strike temperature of 70°C. During this time, he also added calcium chloride and calcium sulfate (brewing salts) to help lower the pH of the mash.
Once Dave added in 250L of foundation water, he started mashing in his grains. The target mash temp was 64°C. Unlike barley, wheat has no husk on it to help with wort filtration, which is why Dave also added 15kg of rice husks to the mash. Rice hulls are the hard outer layers of grains of rice. They are most often used during the production of beers with high percentages of non-barley cereal-grain adjuncts such as wheat or rye.
Wheat was used in this sour wheat beer. Wheat has higher levels of protein and beta-glucan compared with barley and lacks its own husk to help with filtration. Ultimately, higher protein and beta-glucan levels mean a more viscous wort (having a thick, sticky consistency between solid and liquid). Higher viscosity wort may have a harder time draining out the bottom of the mash tun. Rice hulls were added to improve drainage, since rice hulls remain stiff in the mash and help “open up” channels in the bed. This helps to improve the speed of wort run-off. Additionally, rice hulls don’t add any flavour or colour to the mash which is why they are often used by brewers. In total, we added 1200L of hot liquor for our mashing in stage.
3. Saccharification Rest
The rakes were run at full speed during mashing in. They were lowered to a third of the speed for the saccharification rest. The mash was then left for a 60 minute saccharification rest to allow the starches in the malt to convert to fermentable sugars. After 60 minutes, the temperature was increased to a mash-out temperature of 76°C. At this temperature, all enzymes are denatured and starch conversion stops.
4. Vorlauf
Once the mash-out temperature of 76°C was reached, the vorlauf was started. Interestingly, during the vorlauf no grant or other intermediary vessels are used to help prevent compression of the grain bed. The wort is drained from the bottom of the mash tun and goes directly to the top of the mash bed to be recirculated. This helps to clarify the wort as it passes through the natural filter that is the grain bed.
The pump was run at a controlled rate during vorlauf. If it is run at too high a speed it will compress the grain bed, making it difficult to separate the liquid from the solid grain. David continually checked his sight glass to assess the clarity of the wort draining out. When he saw the wort run clear he stopped the vorlauf, about 10min, and began transferring the wort from the mash tun over to the kettle.
5. Transfer
They use a modified batch sparge process here. David transferred 9hL of water over to the kettle. Then, he stopped the transfer process and started the sparge. In total, 1200L of 76°C sparge water was used. 75% of the sparge water was transferred into the mash tun first. The rakes were turned on so that the sparge water and grain were well mixed, and then they vorlaufed again for clarity. When the wort ran clear they transferred the wort over to the kettle. Then they sparged the remaining 25% volume of hot liquor on top, while simultaneously transferring the wort from the mash tun to the kettle.
The reason they started using a modified batch sparge method is because they were not getting good brewhouse efficiency. Brewhouse efficiency is a measure of the amount of extract recovered in the wort compared to the amount of extract available in the malt. It is a measure of how efficient your mashing and lautering procedures are. Their brewhouse efficiency was originally 72%, so they changed to this new method. They also noticed that some of the grain was getting around the rollers on the mill so they narrowed the opening on the mill. With these two changes, the brewhouse efficiency rose to 92%. Just to clarify, batch sparging is not more efficient in general, but it is more efficient for this particular brewhouse system.
6. Boil
Once all the wort was transferred over to the kettle, Dave added fermcap to prevent foaming over. The aim was to collect 2150L in the kettle with a target gravity of 10.9°Plato at knockout. It took the kettle 1.5hrs to fill up. Once the kettle was full the temp was raised to a boil. The wort was then boiled for 60 minutes.
7. Draffing out
While waiting for the wort to come to a boil, Dave turned the rakes up to 20% in the mash tun, this moved the grain and forced more liquid out, making the spent grain drier and easier to shovel out later. Dave also took out two of the plates that made up the false bottom (slotted bottom plate that allows wort to drain through while keeping back the grain) on the mash tun. He rinsed them out and flushed hot water from the bottom of the mash tun to try and rinse out any grain left behind.
8. Pre-Acidifying the Wort
Dave wanted to pre-acidify his wort prior to pitching in the lactobacillus. Acidifying the wort before pitching Lactobacillus has several benefits, such as discouraging unwanted microbes that may have accidentally been introduced into the wort, and helping to prevent Lactobacillus from degrading foam proteins. Although both of these supposed benefits have been challenged by others.
He added about 1.25L of lactic acid to lower the pH of the wort to 4-4.5. The lactic acid was added during the boil. Orange peel and 1.5kg of coarsely crushed coriander seeds were added during the last 8 minutes of the boil. The botanicals were placed in muslin bags so that they could be easily lifted out of the kettle.
9. Whirlpool
After that, the wort was cooled to 60-70°C and 12kg of blueberry blossom honey was added. The strain of lactobacillus that Dave used doesn’t grow well in the presence of hops, this is why no hops were added to the beer. Then he whirlpooled it for 10 minutes and then transferred the wort over to the fermenter.
10. Fermenter Cleaning
While Dave did the brewing today, his coworker Ben cleaned the fermenter to get it ready to receive the wort. The first thing he did was hook the fermenter up to a CO2 tank. The pressure from the CO2 pushed out the yeast sludge from the bottom of the fermenter. The yeast sludge was very thick and didn’t push out easily, so Ben pumped in some hot water to loosen it up and help push it out.
After getting all the yeast sludge out and rinsing the fermenter out with hot water, Ben set up the caustic run. His caustic run was for 30 minutes, with the caustic being 55°C. The tank was then rinsed out with hot water until the water coming out was at a neutral pH. Ben ran peracetic acid through the tank for 10 minutes, and then it was ready to receive the wort.
11. Transfer to FV
The wort going into the fermenter was not oxygenated. The wort travelled from the kettle to the heat exchanger where it was cooled to 35°C before passing through the yeast propagator tank. This propagator was filled with 220L of lactobacillus bacteria culture. The lactobacillus culture soured the wort for two days, lowering the pH even further to 3.2-3.5.
Afterward, Dave attached a carbonation stone to the fermenter and used it to oxygenate the sour wheat beer while he pitched in 220L of a clean ale yeast culture that was in the other yeast propagator. It is common practice when pitching in yeast to also aerate it as Dave did. The scientific reasoning being this is that oxygen is required for yeast to synthesize lipids (sterols and unsaturated fatty acids) to create healthy cell membranes.
The sour wheat beer was left to ferment for another 4-7 days at 21°C, which helped clean up any diacetyl off flavours in the beer. The Berliner Weisse was crash-cooled to 0°C, to knock the yeast and other solids out of suspension. This means that the yeast and other solids naturally fell to the bottom of the fermenter due to the cold temperature change. When the solids fell to the bottom of the tank, Dave simply had to open the bottom valve of the fermenter to remove them. Then the sour wheat beer was transferred over to a brite tank where it was carbonated and readied to be canned, packaged, and sold.
Watch it on YouTube Below
Leave a Comment