I put just a small pinch of malic acid in my Earl Grey tea and now it tastes like regular black tea with calamansi. 
malic acid? whadat?
It's a food additive for acidity in powder form like citric it ascorbic. It's supposed to be synthesized from the acid from apples and pears. Very useful if you want to add acidity to food without adding liquid.
Or ascorbic
Oooh
Found this video.
Why Acids Are as Important as Salt | What’s Eating D...
Why Acids Are as Important as Salt | What’s Eating D...