Acid Tripp Experiment - Fruited Kettle Sour

>> Monday, July 03, 2023

I've been super busy this Spring so I've barely even brewed lately. I recently picked up a pouch of WLP6420 Acid Tripp which is the house kettle souring culture at Tripping Animals out of Doral, Florida. I reached out to White Labs because there seemed to be some contradictory information on their website, but I confirmed it's a blend of bacteria and does not contain any yeast. 

I'm planning on this being a very fruit-forward kettle sour, but I haven't settled on which fruits I plan to use. I may split this up into smaller sized batches and put them on a couple different fruits. I have a bunch of freeze-dried strawberries, and that's definitely the frontrunner right now. Anyway, here is some info re Acid Tripp from White Lab's website:
For the first time, Tripping Animals Brewing in Doral, FL is giving you access to one of their hottest house strains! We’re so excited to partner with our passionate and creative friends at Tripping Animals to bring you WLP6420 Acid Tripp, the ultimate blend of organisms perfect for your next kettle sour. 

This proprietary house blend is used in all of Tripping Animals’ renowned sour ales, and is now available to you!

This culture is unlike any other and offers an extraordinarily complex flavor profile resulting in balanced acidity with moderate tropical and pomme fruit aromas. This complexity allows for a range of flavor profiles that can be achieved depending on how it is blended with other yeasts or added to different beer styles. 

Optimum fermentation temperature range is between 40-43℃/105-110℉ and typically sours the wort within 12-24 hours. 
Complex flavor profile resulting in moderate tropical (pineapple) and pomme (apple) fruit aromas.

An extremely quick pH drop! Souring is typically achieved in less than 24 hours, dropping the wort from a pH of ~5 to ~3.5.

It is recommended to add hops after the lactic acid fermentation so the organisms are not inhibited.
One note, I believe this blend contains at least one heterofermentative strain that will produce a small amount of ethanol, so don't let it go too long as you'll end up boiling off any of the ethanol that's produced. 

Target OG 1.058
Target FG: 1.011
IBU: 11.2
ABV: 6.2%

8.0# Rahr North Star Pils
3.0# Spelt Malt
2.0ml Hopshot (60 min)
WLP6420 Acid Tripp
Wyeast Nutrient
Fruits TBD

Day 1
Single infusion mash at 154F. Collect ~6.75 gallons. Bring to 170-180F and hold for about 15 minutes to pasteurize. Chill to 110F before pitching Acid Tripp. Check pH at least once in 24 hours.

Day 2
Check the pH at least once in the first 24 hours. Proceed with boil when you've reached your target pH (I'm shooting for 3.50). 90 min boil, then chill to 67F and aerate well before pitching yeast.
Water Profile
Nothing fancy here, just 50/50 blend of carbon-filtered tap water and RO water.

Brewing Notes
I got distracted and held the mash around 125F for about 10 minutes before ramping it up to 154F for the duration of the mash. I created a 1L starter of Acid Tripp, partly because I wanted to save some of the blended culture in case I really liked the results. I ended up collecting right about 7 gallons that was chilled to about 110F before pitching 500ml of starter at 7pm on 7/2/2023. I kept the souring keg in my garage because it has the warmest consistent temps right now.

7:20am 7/3/2023: 12 hours in and pH has dropped to 3.66 while gravity has dropped to 10.2 (1.039*). This is a pretty impressive pH drop. I just use ambient temps when kettle souring and with my typical cultures (Yakult and GoodBelly) I often do the first brew day on Sunday, then the second brew day on the following Friday or Saturday by which time I usually hit a terminal pH of 3.2-ish. I tasted the sample and there's some nice tartness and I can pick up some pineapple and pomme fruit character.

5:00PM 7/3/2023: 20 hours in and pH is at 3.41. I lost a few points during souring (I suspect due to heterofermentative strain(s) in the blend). I'm guessing if I caught it at 3.5 the gravity drop would have been reduced. My boil also wasn't quite as vigorous as normal, so that also factors into the lower than target gravity. On the plus side, the tropical fruit aroma was super intense (more so than earlier in the morning) with huge passion fruit, guava, and pomme fruit. Based on aroma alone, I would say this blend is much more complex than a typical kettle sour culture. I think I'll try this culture in a future batch as more of a traditional post-boil sour giving this culture a 12 hour head start followed by a sacc/brett blend.   

Session Readings
Beginning mash pH  5.60 
Ending mash pH  5.56 
1st running gravity  16.2 (1.064) 
Pre-souring pH 5.66 
Pre-souring gravity 10.7 (1.042) 
12-hour souring pH 3.66 
12-hour souring gravity 10.2 (1.039*) 
Pre-Boil pH  3.41 
Pre-Boil gravity 9.7 (1.036*) 
Post-Boil pH 3.42 
Post-Boil gravity 11.7 (1.046)
*Corrected gravity

Update 7/4/2023
I was only able to chill down to about 75F, so I left it overnight to get down to 67F. Yeast was pitched this morning.

Update 7/9/2023
Fermentation has slowed so I pulled a sample this morning. The tropical fruit character is amazing on this beer; definitely much more complex than your typical kettle sour. I’ll probably let this go for a week then I’ll transfer onto fruit. I may even leave part of it unfruited as the base beer is really interesting.

Updated 7/15/2023
I kegged this beer into two 3.5 gallon kegs that are fitted with dip tube screens just like my Kegmenters that I use for fruiting. It's based on Scott Janish's method for dry hopping in the keg and really helps minimize losses due to clogged dip tubes and/or posts.

Keg #1 that I'm calling Citra Tripp got treated with 0.33g lime zest, 0.33g orange zest, 0.66g grapefruit zest, and 3g Citra hops in 2.25 gallons of base beer. Basically I'm looking for some interesting citrus and Citra hop character to compliment the big tropical fruit character from the souring blend. Since there aren't additional sugars being added to this version, it should be ready to drink as soon as it carbs up.

Keg #2 that I'm calling Strawberry Tripp got treated with 1# of freeze dried strawberries (10# fresh fruit equivalent) into 2.5 gallons of beer. I most worried about this one due to the issues in fruiting beers with strawberries. I'm really hoping the strawberry character doesn't turn into something farty or fade too much. I should get a secondary fermentation from all the sugar in the fruit, so this will probably go a few weeks to allow that to wrap up and maximize extraction.

Update 7/19/2023
I pulled a small sample of Citra Tripp. I went pretty conservative on the citrus peels primarily because I just want some fruity complexity rather than it being a citrus bomb. So far so good, there's pleasant citrus character but you don't feel like you're drinking furniture polish/stripper.

I pulled a small sample of Strawberry Tripp the day after transferring onto the fruit, and both the aroma and flavor were great. The secondary fermentation kicked off pretty quickly and I haven't tried it again since then. I'll probably let it go a few more days before trying it again.