Mash Temperature and Fermentables

[Quadrupled]

I brewed my first partial mash yesterday and let the mash temperature start at 158F (I wanted 153, and didn't think to add some ice) and it finished at 150F. What can I expect in regards to fermentables/non-fermentables?

As I understand it, this slightly higher starting temperature favors longer chained carbohydrates and the lower finishing temps favor fermentables. So, will finishing at a lower temperature promote the conversion of the larger carbohydrates released during the early part of the mash?

For what it's worth, the iodine/starch conversion test started deep purple/black and finished light brown.

 

[betarhoalphadelta]

My guess is that this will behave the same as a beer that spent the entire mash in the 158 range. At that temp, you probably denatured the beta-amylase enzymes pretty quickly, so you don't get the greater fermentability you'd have if you started your mash at, say, 145 and warmed it up to 158.

 

[mcaple1]

Either way...it will be beer. But I have often heard that you have a 5 minute window to regulate your temps. I don't think most of the enzymes will be denatured as long as you got to your target temp quick enough. In my opinion, you are going to have a beer that is a bit drier due to the majority of the mash being at 150. Don't worry though, it'll still be beer in the end. And honestly, in another note, people seem to worry sooooo much about their mash temps, but then spend very little or do not realize that their thermometers are probably off by as much as 5 deg F anyway. Unless your using a calibrated thermocoupler, then I would bet you could have been mashing at 150 just as likely as you were mashing at 145 or 155. Definitely spend the extra cash and get an ACCURATE thermometer.

 

[Quadrupled]

Thanks for the answers/advice.

I actually did check my thermometer right before I began the mash and found it to read 206F for boiling water (ice water was about 28F). My reported temperatures are adjusted in an attempt to account for this inaccuracy.

Funny enough, I'm actually a scientist and have said for years how much I dislike the new cheap alcohol thermometers and prefer the nicer mercury thermometers. I guess I'll have to bite the bullet and get a thermapen (or equivalent).