Astringency causes other than grain?

Did a collaboration with some other homebrewers and other friends, made an RIS. It's not totally die yet, and it has some flaws that we are working through/dealing with, and the causes are known. There was one that is boggling my mind, though. The beer has a mild astringency, which is very odd because not only was the temperature of the mash controlled, it was actually low (149, which is also apparent in the dryness). What else could cause astringency besides high temps with grain? None got into the boil, for sure.

Other than barley, used oatmeal, maple syrup (grade c, real maple), and black strap molasses.

Thoughts?

Not apparent in the dryness, apparent in the low finishing gravity and high ABV.

Are you batch or fly sparging?

Elevated pH in the mash and sparge are candidates for extracting tannins and their astringency. High water or wort pH creates a stronger conjugate base and that increases the potential that it will extract the humic acids (tannins) from the grist.

Another potential cause is high magnesium content in the water. High sodium might contribute, but you would typically have a salty taste before that effect is noted.

Fly sparged.


Ok, so water could be the cause. We were at my friends house and used his municipal water. We had never used his before. Haven't had that problem at mine before. Ill have to have him check ph and see if he can get his hands on his local water content. Thanks.

My bet is the roast malt -- some can be pretty astringent especially in high quantities. Phenolic compounds can leave some astringent impressions as well.

The roasted malts in the mash should keep your PH pretty low, probably to the point where you wouldn't need to worry about the sparge PH raising to the point where tannins are extracted unless you sparged with crap out of it, used really hot water, or have water with high alkalinity.