Maybe it was the Brillo pad, just kidding.

We just harvested ours, threw it in a 5 gallon bucket and took the hose to it , (fairly gentle stream) and drained off the water. Directly after the rinse we stripped the leaves and made pesto. Never saw any of the blackening show up.

About yours, I'm stumped.

Bruised during the wash. Be more gentle.

Yep.. That's why the old Italian chefs will tell you to tear basil leaves and not cut with a knife.

Kevin

That looks a bit like bruising, and is exactly the color you get when cut basil is exposed to air for a while. (Oxidation.) That's why you don't cut basil and leave the pieces exposed to the air. Instead, you cut (blend, chop, tear) the basil with oil. The oil covering the leaves keeps the air out. That's how pesto keeps from turning brown.

But yes, when washing the leaves before making pesto, just hose em' down and drain. Don't squeeze or flex them by hand.