sour

Sour is a basic taste perceived in response to acidic compounds. It arises when hydrogen ions from acids stimulate taste receptor cells on the tongue. Common sources of sourness include citric, acetic, lactic, and malic acids found in citrus fruits, vinegar, yogurt, and many fermented products. In taste science, sour intensity is influenced by acid concentration (titratable acidity) and pH, and can be modulated by temperature, texture, and other surrounding flavors.

Sour flavors are widely used in cooking and food preservation. They help balance sweetness, brighten aromas, and act as natural preservatives in pickling and fermentation. Typical examples include lemon and lime juice, vinegar-based dressings, sourdough breads, and sour beers. In beverages and candies, sourness is often intensified with various acids or flavor notes. In wine and fruit products, acidity contributes freshness and structure.

Sour is also the title of the debut studio album by American singer and songwriter Olivia Rodrigo, released in May 2021. The album received broad critical acclaim and achieved substantial commercial success, topping charts in several countries and earning multiple award nominations, including at the Grammy Awards.