Topic summary
Sour

Extracted from the Wikipedia article Sourness.
The most common foods with natural sourness are fruits, such as lemon, lime, grape, orange, tamarind, and bitter melon. Fermented foods, such as wine, sour cream, vinegar or yogurt, may have sour taste. Children show a greater enjoyment of sour flavors than adults, and sour candy containing citric acid or malic acid is common.