acidulant; acidity regulator
A food additive used to impart sourness or control acidity; common in ingredient lists and food science contexts.
This soft drink uses citric acid as an acidulant.
You may see 'acidity regulator' written on food labels.
調味料 is a general seasoning or condiment, whereas 酸味料 is a specific type of food additive for sourness and pH control.
Compound of 酸味 (さんみ, 'sourness') and 料 (りょう, 'material' or 'ingredient'). The term is a modern technical coinage for food additives.