First Kettle Sour - Disaster?

[cheeseyfeet]

Hi Guys,

Yesterday I started my first kettle sour. I'm doing it in my Robobrew, I mashed as normal, sparged, did a quick 10 min boil, brought it down to 40C then pitched 10g of Lallemand WildBrew SourPitch. I set the thermostat on the Robobrew to 38C and left just the low power element switched on.

I have the solid lid that takes advantage of the lid clips on the Robobrew and it has a fairly hefty gasket on it, so I clipped this on leaving one loose - as I had a masterplan for removing Oxygen!

I used to use pressure barrels ages ago and had a load of the CO2 bulbs kicking about, so crafted the following from an old PB cap, bulb assembly, some hose and a camlock fitting.

Locking the camlock into the output from the pump at the top of the recirc gave me a perfect route back down into the bottom of the kettle to inject CO2 and hopefully scrub some oxygen. I did this succesfully with 4 bulbs, then tightented up the remaining lid clip.

Then I think I made my mistake - realising that I now have essentially a sealed vessel, I wasn't sure if lacto fermentation created gas, so didn't want the Robobrew pressuring up.

To resolve this I reused the hose and stuck the end in a jug of starsan, essentially creating an airlock.

I tucked it up to bed for the night. When I went to take a sample at lunchtime today the jug was near empty as all of the starsan had been sucked into the kettle!!

Not to worry I thought , 1.5l of starsan in about 28l of wort - I can live with this. The sample came out at PH 3.9 so a wee way to go. I took another sample tonight and also got a reading of PH 3.9. Thats when it hit me, has that starsan killed the Lacto?

Does starsan kill Lactobacillus?

Bugger! I'm thinking I'll do the following.

Let it ride tonight and see what the PH is tomorrow.
If still no change then I'll use lactic acid to bring it down to 3.1 and carry on with the boil, hopping and fermentation. Crossing my fingers!

Can anyone with experience help?

Cheers!

 

[strange-steve]

Starsan does kill lactobacillus but not when diluted to that extent. Don't worry about it yet, my last kettle sour had zero pH drop after a day and took 2 days to reach pH 3.3. My previous kettle sour didn't get below pH 3.5 but it was really good.

 

[cheeseyfeet]

Cracking, thanks Steve that has reassured me!

 

[cheeseyfeet]

Just checked it again and it has dropped 0.1 PH overnight, so the lacto is still working but quite slowly.

Going to see if I can get it down to at least 3.5

 

[strange-steve]

Did you pre-sour the wort with lactic acid?

 

[cheeseyfeet]

I did, the mash PH was 5.4 and my original intention was to bring it down to 4.5 after the first short boil before adding the lacto.

I guessed and added 5ml of 80% lactic - but this only got me to a PH of 5. At this point I just pitched the lacto as I didn't want to be adding too much lactic acid and continuing to guess what the impact would be!

 

[strange-steve]

I think from memory I added 10 ml to about 22L of wort which brought it down to 4.5. I'm sure it'll turn out well. I love the zingy, lemony smell that comes off the sour wort.

 

[cheeseyfeet]

I must admit, tasting the wort is a strange thing - that much fermentable sugar and acid is a strange sweet sour taste!

My plans for this are to secondary it with a kilo of sour cherry puree to get some colour and flavour into it. I may have to fight the wife for a pint once it's ready!

 

[cheeseyfeet]

Finally got the yeast pitched into this today, it eventually reached PH 3.7, so I boiled it, gave it 5 IBU of saaz and no chilled.

It had been sat until this morning in the cube, I used 2 packs of CML kolsch yeast. It's sitting at 18c now, I'll leave it for a week, give it a couple of days at 20c then rack it to a secondary with the cherry purée.

After the problems I have high hopes!