Butyric acid

[Corn Cracker]

I have some questions about that horrible vomit smelling little bug.

How is it avoided?

Is this only in all grain mashes?
I haven't noticed it in sugar head washes

Is it caused from improper ph?
Seems like an acidic environment would be inviting.

Does letting the mash cool on its own for hours invite it in?
I've gotten it twice, both were left to cool to pitching temp on their own, wrapped up,

I currently have an all corn mash that i cooled down after conversion to get to pitching temp and got a digital ph pen to keep everything just under 5
And no puke smell this time

Just just trying to pinpoint cause and prevention for myself the other novices out there.