I accidentally ate sour soba noodles...

I made a hearty bowl of hot soba noodles with nameko mushrooms, tofu, and deep-fried fish cake (satsuma-age)... but for some reason, the soba noodles tasted sour? Apparently, this semi-dried, shelf-stable type contains pH adjusters for preservation, and if you don't rinse them thoroughly, some of it can remain. They say it's harmless to the body, but I think I'll use dried noodles next time.