Sour starter question

I made a 400ml starter from the dreggs of jolly pumpkin La Roja and Noel in a 1000ml flask. No stirring. I left it about a month, mainly because I wasn't sure which beer to add it to. It had a nice pellicle.

I decanted it because I'm concerned about acetic acid from exposure to 02. I pitched it into an already sour beer, my Bruin. After decanting, I tasted the pour off and it was insanely sour. Much more than anything I've ever had from Cantillon, RR etc. It was actually largely unpalatable, and my fear is that this is from acetic acid (vinegar taste). It didn't taste like vinegar to me, but I also don't really trust my palate enough to make that call.

Should I worry about this in the Bruin which has already been through primary?

Thanks,

First, if it is acetic acid and you know what vinegar smells like, you will know if it is acetic acid because it smells vinegar. If it didn't smell like vinegar, the acetic acid is minimal at most.

Second, even if you have some acetobacter in there the acetobacter would only be able to survive and produce acetic acid while there is both O2 and ethanol present. When fermentation begins there is lots of O2 but no ethanol. As ethanol is produced the O2 is used up in the solution and CO2 is expelled, driving O2 out of your airlock. As a result you have ethanol but no O2 which means no acetic acid production. Even if you get minimal production that adds some complexity to the flavor without getting hardcore vinegar notes.

cool thanks for the info. I didn't use an airlock on the starter, I used AL foil, not sure if that will have an impact.

It did not smell/taste exactly like vinegar, so I guess that it would have been okay to pitch the whole thing in, but I was concerned none the less. I wouldn't have guessed JP dreggs making a beer THAT sour, since none of theirs are incredible sour. I guess that's the difference between adding bugs after primary and adding them for primary.