Expert: Spencer W Thomas - 8/18/2007

Question
strach is not getting converted into sugar from malt,even after mashing it at 60 degree centigrade for 6 hours.i did  a iodin test but it did not convert to sugar... what should i do.

Answer
One possibility is that your thermometer reads incorrectly. 60C is a low temperature for mashing, and if your thermometer reads high, you could be mashing at a temperature too low for effective starch conversion.

Another possibility is that you are not doing the iodine test correctly.  You should take only clear liquid for the iodine test.  Any husk fragments or particles of malt *will* turn dark in the test, and fool you into thinking starch conversion has not finished.  (See http://howtobrew.com/section3/chapter14-5.html).  As a quick check, you can taste the liquid.  Is it sweet or does it taste "flat" and starchy?  If it is sweet and clear, mashing has finished despite the iodine result.

A third, less likely possibility is that your mash pH is too high or too low.  Usually, the mash pulls itself into the proper pH range, but if the water is has high carbonate or bicarbonate content, your pH could be too high for effective starch conversion.  (See http://howtobrew.com/section3/chapter15.html for details.)