The iodine test: my simple trick during the mash
When I started brewing, I blindly assumed that a 60- or 90-minute mash was always enough. Nothing could be further from the truth: plenty of factors affect the conversion of starch into sugar. That's why on every brew day I now check whether that conversion is really complete, and the iodine test is my simplest tool for it.
The iodine test is very straightforward: you put a few drops of iodine solution on a sample of your wort. If there's still starch in it, it turns blue, purple or black. If the colour just stays yellow or brownish, all the starch has been converted into sugars and you can carry on brewing. More sugars also means higher efficiency, so you really always come out ahead.
Here's how I do it: I scoop a tablespoon of wort from the mash onto a small white plate, let it cool for a moment and add a few drops of iodine solution. The colour tells me right away whether I need to keep mashing. Once my measured SG came out lower than the recipe said; thanks to the test I immediately saw that conversion wasn't finished yet, and I calmly mashed a bit longer.
Do keep an eye on the conditions, though, because they determine how quickly the starch is converted. The mash temperature is best between 62 and 72 °C, the pH between 5.2 and 5.6, and pale malts contain more active enzymes than dark, roasted grains.
My tips: always use a white plate, because the colour change is hard to see on a dark one, and rinse the plate right away so you don't mix in leftover wort. I like to combine the iodine test with a refractometer: once the SG stops rising, the starch test confirms whether conversion is complete.
Source: Hopblog.nl
The iodine test is very straightforward: you put a few drops of iodine solution on a sample of your wort. If there's still starch in it, it turns blue, purple or black. If the colour just stays yellow or brownish, all the starch has been converted into sugars and you can carry on brewing. More sugars also means higher efficiency, so you really always come out ahead.
Here's how I do it: I scoop a tablespoon of wort from the mash onto a small white plate, let it cool for a moment and add a few drops of iodine solution. The colour tells me right away whether I need to keep mashing. Once my measured SG came out lower than the recipe said; thanks to the test I immediately saw that conversion wasn't finished yet, and I calmly mashed a bit longer.
Do keep an eye on the conditions, though, because they determine how quickly the starch is converted. The mash temperature is best between 62 and 72 °C, the pH between 5.2 and 5.6, and pale malts contain more active enzymes than dark, roasted grains.
My tips: always use a white plate, because the colour change is hard to see on a dark one, and rinse the plate right away so you don't mix in leftover wort. I like to combine the iodine test with a refractometer: once the SG stops rising, the starch test confirms whether conversion is complete.
Source: Hopblog.nl
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