Is there any need to have a separate mash tun for sour mashes? Just wondering if there would be any sanitation issues with using my normal mash tun for sour mashes as well. Thanks!
No. You’re good to go.
The smell might be hard to get out if you are using a cooler tun. I left some grains overnight once out of laziness. I yacked while dumping them out and had to let the cooler soak with oxyclean for a few days to get the smell down. That was an extreme case.
It may retain the smell, affecting the taste of subsequent batches, but it shouldn’t “infect” a subsequent mash which would be quickly boiled following the mash…but another extended sour mash could be affected in theory.
Don’t think I am getting this right. Isn’t the mash the same as any other beer?
A sour mash uses lacto in the mash before boiling to sour a beer. Typically it is allowed to sour for a day or two, but maybe longer. It can leave some funky smells from the lacto and other bugs that were already on the grain.
Ok. Why do you sour the mash prior to boil and not in the fermenter?
A sour mash in the kettle or mashtun helps to keep all your equipment downstream bug free. It also allows for greater control over how sour a beer will be in the end. A brewer can pour lacto into a warm (~100°) mashtun and taste daily to find the level of tartness they like.
All this talk is making me want to brew a berliner.
Souring in the kettle post sparge is a good option as well. A good fitting lid is required, but I have heard of others laying plastic wrap on the mash surface. From what I have heard, if you kettle is small enough, an oven with the light on is a good way to hold a warm mash over a day or two.
And with the lactobacillus on the grain husks as you mash, adding lactobacillus to the mash may be unnecessary. It still can be added, of course.
Grain is already covered in lacto and other bugs, so I wouldn’t worry about contamination. But like others said you might not get the smell out. I doubt the smell alone would absorb enough to affect future batches but I might be wrong.
In my experience the smell will be gone after your next batch. No worries. I have done that several times.