Kettle Souring - Time & Magik
Brewing here at Elusive is a constant learning experience, driven by developing and expanding our knowledge, not being afraid to try new things and taking on board trade and consumer feedback. Yes, the old adage of brewing the beers we want to drink plays a part but if we were the only ones who wanted to drink them, we wouldn’t be around long!
We like drinking kettle sours, especially vibrantly fruity numbers, and it seems others do too given their rise in popularity in recent years. So, we decided to dabble in late 2018 with the release of Time & Magik, a simple, lower ABV (3.7%) kettle sour with added raspberry & blackberry puree. Kind of an autumn fruits affair. Time & Magik was a trilogy of text adventure games release in the 80s. The name seemed appropriate to the art of kettle souring. Time is certainly required but the souring itself is more science than magic, and understanding that science is something we’ll be looking to do as we develop what will become a series of beers under the same name.
The resultant beer was one we were fairly happy with - certainly super drinkable and refreshing - but we felt we could push the sourness and fruitiness further to give it more snap and also felt it could use more body over the palate. So, with these considerations in mind, we revisited the malt bill, water treatment and souring process and also gave more thought to the fruits being used - not quite starting from scratch, but certainly stripping the whole thing back to basics armed with the numbers and sensory analysis of the first iteration.
On consideration, we didn’t tinker much with this. It’s fairly typical of the style, incorporating a mix of lager, wheat and pale malts.
Lager Malt (50%)
Wheat Malt (33.3%)
Pale Malt (16.7%)
This gives a low overall EBC, which also helps the finished colour better reflect that of the fruit being added. Also, more practically, is six 25Kg bags for target OG of 1.040 (3 Lager, 2 Wheat & 1 Pale).
We did tweak this, favouring a softer profile, which might seem at odds with what we’re looking to achieve but it has certainly helped add a perception of body to our hazy pale series. We figured that if we get the pH down in the finished beer and softened the water, the two combined would get us closer to the mouthfeel we wanted and away from the slight thinness the first beer presented.
Our base water is moderately hard with a total alkalinity of 282 (ppm). Treatment here involved reducing the mash pH to 5.3 with lactic acid (which we’d use again later for pre-souring) and using calcium chloride flakes and gypsum to target 150ppm chloride and 100ppm sulfate, helping to enhance the malt profile.
The first brew used Lallemand’s WildBrew Sour Pitch product, which is a pure, isolated lactobacillus plantarum strain selected for its fast performance, citrus flavour/aroma and clean sourness. It comes in dried form, in a 250g sachet, which is enough to inoculate 10BBL of wort at the suggested pitching rate, so we used half given our 5BBL brew length. Actually, we used the second half of the sachet we’d used for the first brew, which had been vacuum packaged and stored in a freezer since opening. Lallemand have a best practice document that offers some tips for getting the best out of their product.
We took this on board and followed their recommendation of mashing as per our existing process and performing a (hop-free) short boil post wort collection, after which we dropped the temperature down to 39C by recirculating through the heat exchanger. This is at the top end of the suggested range, but we figured the kettle would lose a few degrees between pitching and the lactobacillus taking hold. As the Sour Pitch was re-hydrating in 30C water, we pre-soured the wort to 4.4pH using food grade lactic acid. The best practice document suggests this helps protect against unwanted microbes and aid head formation in the finished beer. A fascinating twitter exchange (scroll down the thread) with Mike Marcus of Manchester’s Chorlton Brew Co questioned the need to perform these steps as their own experimentation had found no difference in A/B testing. Chorlton are highly respected for their clean lactobacillus soured beers and their output is 100% dedicated to them, using a strain they isolated and cultivate in house. Further, Mike indicated that the ‘two boil’ approach had, in their experience, seen less DMS driven off overall with a risk, therefore, of more sulphur being present in the finished beer. Interesting stuff which we’ll file under the need for us to understand more of the science at play here!
Before pitching, we disassembled the pipework leading into our kettle and remove the steam flue before a liberal purging and blanketing with food grade CO2. Given our kettle is ‘open’ with a wooden lid, we wanted to be extra careful here, to reduce the risk of any nasties getting to our wort during souring, so the kettle was further protected with pallet wrap, cling film and a thorough spraying with peractic acid - better safe than sorry!
The starting pH was 4.4, on pitching at 3pm. By 9am the next day, the pH was measured to be 3.4. Based on us wanted a lower overall pH (taking into account dilution through fruit additions etc.) in the finished beer, we left it until the following morning by which point we were at 3.1pH. The makeshift kettle armoury was disassembled and replaced with the original pipework and flue before the elements were turned on for a further 60 minute boil. This too was hop-free, save for a handful of T90 pellets thrown in to help reduce boil-over risk. The wort at this stage tasted like lemon sherbet which morphed into apple pie during the boil - lush!
On transfer, 20L of Sour Cherry and 20L of Blackcurrant puree was added along with a good dose of HopAid antifoam from Simply Hops. With no loss to hops and the dilution/volume added by the puree, the FV was looking fairly full and we find this product really helps keep the krausen in check, maximising our packaging yield and minimising wort loss over the top of the FV - which is crucial given our small brew length!
For primary fermentation, we selected a clean American ale strain known for its high performance and low ester production which we’ll further keep in check by holding it at the lower end of its range at the start of fermentation. We’ll monitor the beer throughout primary fermentation to determine if more fruit should be added towards the end of primary fermentation to achieve the desired result.
Time (and Magik) will tell if this second iteration improves upon the reception of the first!