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Iodine test: Difference between revisions
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There are some instances when a false negative may occur: | There are some instances when a false negative may occur: | ||
*If the sample is too hot, the test does not work because hot starch will not change color in the presence of iodine.<ref name=kunze/><ref name=kai/><ref>[https://en.wikipedia.org/wiki/Iodine%E2%80%93starch_test Iodine–starch test] Wikipedia website. Revised November 2020. Accessed December 2020.</ref> It must be cooled to room temperature before testing. | *If the sample is too hot, the test does not work because hot starch will not change color in the presence of iodine.<ref name=kunze/><ref name=kai/><ref>[https://en.wikipedia.org/wiki/Iodine%E2%80%93starch_test Iodine–starch test] Wikipedia website. Revised November 2020. Accessed December 2020.</ref> It must be cooled to room temperature before testing. | ||
*Some cereal starches contain [[fatty acids]] as inclusion compounds. These lipid-starch complexes do not change color with iodine, and therefore some incompletely degraded starch may go undetected.<ref name=bsp>Briggs DE, Boulton CA, Brookes PA, Stevens R. [[Library|''Brewing Science and Practice.'']] Woodhead Publishing Limited and CRC Press LLC; 2004.</ref> | *Some cereal starches contain [[fatty acids]] as inclusion compounds. These lipid-starch complexes do not change color with iodine, and therefore some incompletely degraded starch may go undetected.<ref name=bsp>Briggs DE, Boulton CA, Brookes PA, Stevens R. [[Library|''Brewing Science and Practice.'']] Woodhead Publishing Limited and CRC Press LLC; 2004.</ref> It's uncertain whether this has any practical significance. | ||
*If the mash temperature is somehow too low for the starch to gelatinize, the wort will not contain starch and therefore not test positive. The iodine test is not useful for detecting this particular mashing issue. | *If the mash temperature is somehow too low for the starch to gelatinize, the wort will not contain starch and therefore not test positive. The iodine test is not useful for detecting this particular mashing issue. | ||