Phenolic flavor from incomplete starch conversion?

Hey there,

My last batch (strong rye beer w/ 23% rye) is drinkable and enjoyable, but when I brought it to a local brewpub, the brewers there said it was phenolic. My ceiling for sparge temp is 170, so they said it was probably due to incomplete starch conversion, and starch in the boil. Could there be another cause? It tastes very slightly of uncoated aspirin, but it is not a bacterial infection. Would there be any other effects of a mash w/ incomplete starch conversion?

I mashed this at around 151 for 60 minutes. What can I do to ensure that all of the starches are converted in future brews? How does the iodine test work? is it as simple as removing a little of the liquid from the mash and dribbling some iodine in it? any thoughts on what else could cause a slightly phenolic off flavor?

I can't think of any way incomplete conversion can cause that. If you mashed at 151 for 60 min., you can be pretty much certain you got conversion. It sounds like you were fed a load of bull. Unless they were mistaking the rye taste for phenolics. What kind of phenol does it taste like? If it's chlorophenolic....Is your water chlorinated? If so, did you remove the chlorine/chloramine? Do you use bleach to sanitize?

im not sure if my water is chlorinated (NYC tap water), but I have had previous batches that have not had this off flavor, so it is pretty safe to say it is not the water. I use starsan to sanitize, so that rules that out as well.

Incomplete conversion will reduce your efficiency and starch in the boil will make your beer cloudy. Neither will cause phenolic (medicinal) flavours. Yeast make phenol compounds, most we don't taste, chlorophenols from chlorinated water have a very low taste threshold. I'd think about your water again. The amount of chlorine in water supplies can vary alot over time depending on the source.

GT

Incomplete starch conversion is not the cause. Please post the name of that brewpub so we can avoid their beer. Likely causes are an infection, high temps during primary ferment, or contamination. If you are on the main NYC water supply from upstate I think the chlorine level is extremely low or non-existent.

I really wish I could taste your brew to understand what your talking about better.

Chlorine and Chloramines, wouldnt they both evaporate during the boil? Or are you talking about reaction during the mash?

Most Rye beers I have had carried a dry, mineral heavy flavor; have you made the same recipe before without a strange flavor?

CreeDakota said:

Chlorine and Chloramines, wouldnt they both evaporate during the boil?

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Chlorine does but chloramines do not. Even though chlorine will leave water when it's heated if the level is too high to begin with the chlorine can react with other molecules and form those chlorophenols.

CreeDakota said:

Chlorine and Chloramines, wouldnt they both evaporate during the boil? Or are you talking about reaction during the mash?

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Yes, but by time they've bonded with compounds in the wort and the damage is done,