I've known people that used to drink the juice of 10 lemons a day to try to alkalinize their bodies. I may have even been on that bandwagon myself at one time.
I'm very familiar with what foods are acid or alkaline forming, (at least for my own body). I'm not saying we are all alike. I think we vary in many things.
For my body, I've found :
All Citrus = alkaline forming, though very acid going in, esp. lemon and lime
Most Berries, cranberry, plum, prune, Pomegranate = acid forming (it's that way w/me because these are some of the only foods I can tolerate if/when I'm too alkaline)