I was reading another question here and it appears that the consensus is that the iodine test isn't all that useful if your recipe is good. But, while reading through everything, I had a thought: if you're hitting your OG, is there anything bad that might be caused by starch remaining in the beer (e.g. extra haziness, early spoilage, possible food for infections)? Or will it just settle out/remain harmlessly in solution?

  • Good question. This will obviously have ramifications for my "dry-malting" idea.
    – Poshpaws
    Commented Sep 12, 2011 at 9:19
  • Just to be clear, residual starch is a function more of process errors not so much a function of a good (or bad) recipe.
    – brewchez
    Commented Sep 12, 2011 at 13:32

2 Answers 2


Yeast cannot metabolize starches, so any starch left provides a food source for infections. You can also get starch haze from too much unconverted starch. In general starches are bad things and should be avoided as much as possible.


I have yet to have an infected batch so I cannot really comment too much on the problems of unconverted starch in your beer. However, this page is quite interesting. There are two tables provided giving data on the use of adjuncts/unmalted grains and malted grains. The author has a little rant about the evils of starch and that

"With the exception of Roasted Barley these grains must absolutely be mashed with enzymatic grains in order to convert their starches to sugars. Do not under any circumstances use these without doing so."

"Starch bad. Sugar good."

Scary stuff, but I do get the point.

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