Sour Mashing with Unmalted Grain?

I wanted to conduct a 24hour+ sour mash in my oven.  I’ve heard, but cannot confirm that you shouldn’t use unmalted grain in a sour mash.  Can someone back this up?  I was planning on doing 7oz rolled oats.

Cheers,
Michael

I have no idea why unmalted grain would be any different for this purpose.

I guess there might be more bacteria/fungus on unmalted grain as it never went through any heat treatment but I don’t know this to be true, or germane. where did you hear that you shouldn’t?

Sour mashes can be finicky enough to coax out the right flavors.  If it were me I would probably add malted grains as is traditionally done.
A lot of people will make a small 2qt starter of DME wort and simply add their grains to that and allow it sour first.  Then decant/strain and pitch just the “lacto” harvested that way into their full size batch to ferment out.  This allows one to taste and judge the starter wort and see if it is worth pitching into the larger batch first.

I’m afraid to admit it but the “internet” said so… Not that i was 100% sold on the information when I came across it, but it triggered the exact thing that you mentioned about bacteria/fungi/whoknowswhat… I think I’ll proceed with the oats in the mash anyway, and maybe give things a little lacto head start as suggested.

Lowering your pH to about 4.5 prior to pitching should also help inhibit the nasties from taking hold.

That sounds like something one person said and a lot of other people repeated until it became accepted truth.