We can bring some fruit with vitamin a acid to remove stains on the coins. And if you want a value rating of acid can then be sorted, there kinds of fruit acid which is the maximum acid value.
We can bring some fruit with strong acidity to remove stains on the coins. Or not, and if the pH level must be. Can sort that kind of fruit acids are the most acidic.
We can take some fruits effects pH to stains on the coins Or not, and if need to arrange the level pH value will be Can sort that the acid from the fruit. What kind of value maximum acidity