Seeds are full of carbs, minerals and proteins. Malting makes most of the calories water soluble which is why you malt grain to make alcohol. But even without it a little bit will make it into the broth.
What surprised me is the ratio of calories in black coffee versus espresso. I wonder if it’s solubility or the fact that fines make it through a screen but not a filter.
Seeds store calories as complex carbs to avoid rotting and I think predation. When the seed decides to sprout, it converts the carbs to sugars so it can put on a growth spurt. In a way, microgreens are tapping into a knowledge that brewers have had for ten thousand years or more. They don't call it 'liquid bread' for nothing.
I wonder what coffee beer tastes like. I've had espresso beer (when I could still eat wheat), but that's the sizzle, not the steak.
Colloquially known as a bean, but it's really a seed similar to a cherry pit. The fruit is actually known as "coffee cherry" and is edible.
https://coffeechronicler.com/coffee-cherry-taste/