Incomplete starch conversion?

[nrjones89]

I did my second AG brew yesterday (actually did two brews, but this thread is about the first one). It was a golden ale with pils malt, 8oz crystal 10, 8 oz melanoidin. I'm concerned that I maybe didn't get a complete starch conversion. My mash temps were 152-154ish, but I didn't account for the malt dropping the temp. A bit over an hour later when I removed my brew bag and malt, my temp reading was in the low 130s. I took a sip of the gravity reading when it was chilled, and it tasted kind of watery at 1.040.

Does it sound like I got an incomplete starch conversion? Should I get some iodine to test? Any way I can fix this if it didn't complete?

 

[JimRausch]

What is your predicted OG? Did you take a SG reading? A preboil SG of 1.040 will give you an OG somewhere around 1.050, depending on your boiloff rate. Sorry, can't help you much with incomplete information. I do believe that running an iodine test now, after boiling and presumably pitching your yeast, would be a waste of time. That horse has left the barn. There are enzymes you can add to convert more starch to sugar, but I know nothing about those other than what I've read.

 

[nrjones89]

It was 1.050 post boil. I added water to get it to 1.043, which was what I was targeting.

 

[JimRausch]

It was 1.050 post boil. I added water to get it to 1.043, which was what I was targeting.

I think there's your answer then. You had to have adequate conversion to make it over your predicted OG. You are good to go!

 

[nrjones89]

I read online that a hydrometer reading will account for sugars and starches in the solution. So how can I be sure that the conversion is complete based on the gravity? Or was that information wrong?

 

[kevin58]

Have you learned about iodine starch conversion tests? Put a drop or two of your wort on a white plate or saucer and add a drop of iodine. If the color changes to an amber/yellow color then your conversion is complete... if the color is black/purple then conversion is not complete and you need to mash longer. Also - why didn't you check mash temp after you stirred in your grain? You could have added some hot water at that point to get up to your desired mash temp right then and there.

 

[balrog]

The enzmatic conversion from starch to sugar will happen pretty quickly. Depends on crush size, which will determine when the starches are finally available in solution (big pieces take longer). Us BIAB-ers who mill-to-dust can have conversion pretty much done in 10m, but I always go at least 45m for flavor and whatnot. I do not think holding mash 1hr in is a big deal, and if you are within a few degrees at 10-20m in you are fine.

 

[JimRausch]

I read online that a hydrometer reading will account for sugars and starches in the solution. So how can I be sure that the conversion is complete based on the gravity? Or was that information wrong?

Nope. Hydrometers measure the SG of solutes in solution with water- sugars, salts, alcohol. Any starch present will be in suspension, not solution. That's why hops and trub don't affect SG. You can check by adding some table salt, or sugar to water and take the SG. Then dump in some flour. The reading won't change unless you added so much you physically lifted the tube.

 

[nrjones89]

Big AHA moment. Lightbulb finally on, thank you!

 

[RM-MN]

The enzmatic conversion from starch to sugar will happen pretty quickly. Depends on crush size, which will determine when the starches are finally available in solution (big pieces take longer). Us BIAB-ers who mill-to-dust can have conversion pretty much done in 10m, but I always go at least 45m for flavor and whatnot. I do not think holding mash 1hr in is a big deal, and if you are within a few degrees at 10-20m in you are fine.

Conversion is even quicker than that. It does take more time to extract the flavors but for that the temperature isn't critical so the temperature loss is of no consequence. I don't recommend a mash of less than 30 minutes to get the proper flavor.