I would like to add chia, flax and sunflower seeds to my sourdough breads for added nutrients. Unfortunately the nutrients in seeds are very fragile when it comes to high temperatures.
Would the baking temperature of 450 f. destroy the fragile nutrients?
Secondly, I'm guessing I should soak the seeds first before adding to the dough, correct?
Normally, chia seeds need to be soaked anyway before eaten to take advantage of the the nutrients.
Heat will destroy some things but not others. I don't have extensive knowledge on this, but for one example, I've read that baking flax destroys the compounds that we metabolize into cyanide* but does not decrease the lignans.
If want them in your bread but are concerned about loss of heat-sensitive nutrients, consider also eating some seeds raw in other applications.
*Humans do metabolize low doses of cyanide, so limited amounts of raw flax seeds are generally considered safe.
That's the oven temp. Inside the dough - its core - the temp is far lower. Either way - soak them enough to soften but not so much that it breaks down. It sounds like it's time to experiment. Enjoy!
Remember, the crumb isn't going to get above the boiling point of water. That's enough to disable any likely enzymes but maybe not everything.
TomP