Grapes and tamarinds have the highest levels of tartaric acid concentration. Other fruits with tartaric acid are bananas, avocados, prickly pear fruit, apples, cherries, papayas, peaches, pears, pineapples, strawberries, mangoes  and citrus fruits.
Trace amounts of tartaric acid have been found in cranberries and other berries.
Tartaric acid is also present in the leaves and pods of Pelargonium plants and beans.