The importance of heat stress

[Techbrau]

I just wanted to share some anecdotal experience and photos concerning heat stress in the boil.

For a little while several months back when we were still figuring out the LODO process, I was experimenting with longer boils with a higher boiloff rate. I was getting lots of color pickup, and the post-boil wort lost most of the fresh malt flavor that was in the mash. The finished beer also lacked the nice flavor. We then went to the short, gentle boil and saw tremendous improvement - dramatically improved taste, and far less color pickup.

Here's a picture of some pre-boil wort from a few months back:

preboil1_small.jpeg (327.47 KiB) Viewed 11302 times

And here's the same wort post-boil, pre-chilling (so no cold break has formed yet). This was just under a 2 hour boil with nearly 30% total evaporation:

postboil1_small.jpeg (346.22 KiB) Viewed 11302 times

[Techbrau]

Now, here's some pre-boil wort from a couple weeks ago:

preboil2_small.jpeg (298.73 KiB) Viewed 11300 times

And the same wort post-boil and post-chilling (so there's some cold break clouding the sample). This was a 60 minute, gentle boil with less than 10% evaporation.

postboil2_small.jpeg (321.81 KiB) Viewed 11300 times

This beer is currently lagering, and the wonderfully deep fresh malt flavor is still there. The color lightened during fermentation. Here's a pic of a sample taken from the lagering keg:

lagering.jpg (321.88 KiB) Viewed 11259 times

The 96/4 baseline recipe from the paper should be incredibly light - check out the pictures Bryan has posted of his helles here: viewtopic.php?f=12&t=11&start=90

If your finished beer (made with the 96/4 or a similar grist) is turning out significantly darker than Bryan's photos, you likely have too much oxygen exposure, too much heat stress, or both going on in your process.

[Bryan R]

For reference, here is a video of my boil intensity.
https://www.youtube.com/watch?v=7yMUYa0-QpQ

Too much intensity:
https://www.youtube.com/watch?v=k8CiVs6kOA8

[Brandon]

Timely discussion, I listened to this Brew Strong Podcast on Thermal Stress last night:

http://www.thebrewingnetwork.com/brew-s ... rmal-load/

I've been dialing in boil duration and intensity for the past few brews as well.