醬油裏的防腐劑苯甲酸鈉是某些食物裏天然存在的

Sodium benzoate itself isn't found naturally, but benzoic acid, its salts, and esters are naturally present in many foods. Fruits and vegetables, especially berries like cranberries and bilberries, are good sources. Seafood like prawns and dairy products also contain these compounds.