Catharina Sour 2021

Today I'm brewing a style I've never brewed before, a Catharina Sour. This is a style that originated in Brazil and is along the lines of a heavily fruited Imperial Berliner Weisse. I haven't come across an actual Brazilian Catharina Sour at any bars or bottle shops, but I've definitely had lots of very fruit-forward sours, so I feel like I have a decent understanding of what the style is supposed to be. The BJCP guidelines describe the style as follows:

Impression
A light and refreshing wheat ale with a clean lactic sourness that is balanced by a fresh fruit addition. The low bitterness, light body, moderate alcohol content, and moderately high carbonation allow the flavor and aroma of the fruit to be the primary focus of the beer. The fruit is often, but not always, tropical in nature.
Comments
If a Berliner weisse type beer was made with fruit, it should be entered as a Fruit Beer. This beer is stronger and typically features fresh fruit. The kettle souring method allows for fast production of the beer, so this is typically a present-use style. It may be bottled or canned, but it should be consumed while fresh.

This is a kettle sour beer, and as a general rule kettle sours tend to have less complexity compared to traditional sours (e.g. post-boil mixed fermentations). Sometimes kettle sours result in one dimensional lactic sourness, but in this case the heavy fruiting contributes complexity. The version I'm brewing will feature pink guava and passionfruit at a rate of close to 2 lbs per gallon. I've had mixed experiences with guava in commercial sours, so I’m rolling the dice on this beer. For example, the first guava beer I had from The Bruery had a character that I would describe as baby-poop...not super pleasant. Later on I tried a different guava beer from them and it was absolutely amazing, so I'm guessing (hoping) maybe that first one had some over ripe fruit or was a different variety (fingers crossed). Passionfruit is a favorite of mine in sour beers and tiki cocktails. It can add a fair amount of acidity, so you have to be careful that it doesn't result in an acid bomb beer. I'm brewing this as we're heading into Fall, so this beer will kind of extend summer a bit as the weather starts to cool.

This recipe is based on the BYO recipe, here. Here it is as I'm brewing it today:

4.6875# Root Shoot Pilsner

2.375# Best Malz Spelt

1ml Hop Shot (60 min)

4.4# Pink Guava aseptic puree (Secondary)

4.4# Passionfruit (Secondary)

(3) Yakult Probiotic Drink

Safale toUS-05

Water Profile - To RO water, add:

• 0.31g/gallon Gypsum (CaSO4)
• 0.36g/gallon Calcium Chloride (CaCl2)

Brew Day 1

This recipe incorporates a step mash consisting of the following steps:

• Mash in at 122F for 5 min.
• 153F for 70 min.
• Mash out at 169F for 10 min.

Collect about 6.5 gallons of wort and bring to 175F for 15 minutes to pasteurize. Chill to 98F to 109F and adjust pH to 4.5 before pitching Yakult Probiotic Drink. Hold at warmish temps until desired pH is reached; for me that's in the neighborhood of 3.2-3.3. Note: Most lactobacillus cultures will sour just fine at room temp, it just may take a few days. If you have the ability to apply gentle heat, shoot for a constant temp around 109F. If you don't have the ability to heat, let it ride in the warmest room in your house.

Brew Day 2

Transfer soured wort to boil kettle and proceed with boil. Chill to 65F before pitching yeast.

Fruiting in Secondary

I prefer to go with fresh fruit whenever possible, but there are some really good aseptic purees nowadays, so that's what I'm using for the guava. For the passionfruit, I went with frozen 100% passionfruit pulp that I found at a local Asian grocery store. 

I usually rack onto fruit towards the end of fermentation to get the beer off the trub. Since fermentation isn't as active, there's less risk of blowing off fruit aromatics. I'm going to rack onto fruit in a keg and that's been set up to use the pickup tube screen I outlined in Minimizing Loss post. I'm going to use my spunding valve to regulate pressure during the fruiting stage, and will probably force carbonate and bottle right off the same keg when this beer is "done".

Brew Day 1 Notes

I ended up collecting a little over 7 gallons in the boil kettle so my pre-boil gravity was a little more diluted than planned. Other than that, no issues. 

Readings
Beginning mash pH	5.28
Ending mash pH	5.46
1st running gravity	18.3 (1.073)
Pre-sour gravity	6.5 (1.025)
Pre-sour pH	4.54
Pre-boil gravity (post-sour)	7.0 (1.027)
Pre-boil pH (post-sour)	3.20
Post-boil gravity	11 (1.043)
Post-boil pH	3.20

Update 10/5/2021

I pulled a small sample today to check on the souring process and the pH reading was 3.37. I didn't have time tonight, but I'll probably finish up boiling tomorrow night.

Update 10/7/2021

I didn't have time to do the boil yesterday either, so I'm doing it today. Notice in the table above I took another gravity reading and it's actually higher than the Day 1 reading. This is most likely due to temp differences and/or the wort not being uniformly mixed on the Day 1 measurement. pH has dropped to a surprising 3.20; that's great but I wasn't expecting it to get quite that low. The soured wort has been transferred to the BK so I'm starting Brew Day 2.

Brew Day 2 Notes

No issues. I boiled an extra 20 minutes to get the gravity to 11 (1.043) so the total volume is about 4.4 gallons which should be great once the fruit is added.

Update 10/8/2021

Yeast was pitched about 7:30pm yesterday. This morning I'm seeing a glug out the blow-off assembly about once every 10 seconds. Oh, I really doubt I'll have any blow-off due to the lower volume, they just work really well so that's what I usually use until I'm ready to come crash a beer.

Update 10/11/2021

Gravity was down to 1.010 today so I started prepping the fruit. The guava puree is aseptic and the fruit has been pasteurized, so I didn't have any worries there. On the other hand, the passionfruit didn't have anything on the packaging indicating it had been pasteurized so I added 1/4t potassium metabisulfite dissolved in 1/4c of RO water to sanitize. This will be left overnight to offgas the sulfur. Tomorrow I'll rack onto the fruit in the keg. I also treated the fruit with 1ml of pectinase hopefully avoid any chill haze in the finished beer.

Update 10/13/2021

I racked the beer onto the fruit in the keg last night. It basically filled the keg to the brim, so I had to draw off about a 10oz to make sure secondary krausen doesn't push up through the gas post where the spunding valve is attached. The sample tasted amazing. The spunding valve is currently set to about 2.5 PSI and the beer will sit on the fruit for at least a couple weeks to ensure all fruit sugars have fermented out. Also, no baby poop character from the guava!