en:E331iii

Sodium citrate may refer to any of the sodium salts of citrate -though most commonly the third-: Monosodium citrate Disodium citrate Trisodium citrateThe three forms of the salt are collectively known by the E number E331. Sodium citrates are used as acidity regulators in food and drinks, and also as emulsifiers for oils. They enable cheeses to melt without becoming greasy. - Wikipedia