Low Oxygen Boiling

After reading Kunze we found that thermal stress on wort is a real thing and we can taste it too. When experimenting with longer boils with a higher boiloff rate there was more color pickup and the wort then lost most of the fresh malt flavor that was present pre-boil. The resulting beer was not smooth and drinkability and flavor suffered. Going to a shorter, gentle boil showed a lot of improvement. Far better taste, less color, and all around a better beer.

Kunze talks quite a bit about thermal stress and here are some excerpts from him:

47b5fb20380ef4f426354fccfb9ff849 820e7d831bc60ffe0effac010f8038d4 0931eb4d17bd49bf3987e67b87aa34e6 93232fbb8c2096f4593db17e10b46229 d19c1a7b06c4fe1fc3e9c19dbd6f9478

After reading Kunze I fashioned a new boil kettle lid, with a small cut out to allow for less thermal stress from the element, while still allowing for the steam to escape.

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For reference, here is a video of my boil intensity.

You should be targeting a simmer rather than a rolling boil.

It’s definitely something to play around with and fine tune in your process.