lemon juice or red wine vinegar

Lemon juice is the acidic liquid extracted from lemon fruit (Citrus limon), a small citrus fruit native to Asia with a bright yellow color and distinctive sour flavor. The juice comprises approximately 5–6% citric acid, along with ascorbic acid (vitamin C), flavor compounds, and minerals. Lemon juice is prized for its bright, clean acidity and aromatic quality that enhances both savory and sweet dishes without adding sodium or fat.

Fresh lemon juice has a sharp, slightly floral citrus character and ranges in acidity depending on the fruit's ripeness and variety. Bottled versions are commonly available but often contain preservatives and lack the complexity of freshly squeezed juice.

Lemon juice serves as a fundamental acidic agent across Mediterranean, Asian, and modern cuisines. It is used to brighten flavors in seafood dishes, dressings, marinades, and sauces; to prevent enzymatic browning in fruits and vegetables; and as a key component in beverages from cocktails to lemonades. In baking, it adds tang to cakes and curds. The juice is essential in cuisines ranging from French (vinaigrettes, beurre blanc) to Middle Eastern (tahini sauces, hummus) to Asian (Vietnamese dipping sauces, Japanese ponzu). Its acidity helps tenderize proteins in marinades while its flavor complements nearly all savory ingredients.