noun
sulfite
Technical term in chemistry; refers to a salt or ester of sulfurous acid.
この食品には亜硫酸塩が保存料として使われている。
Sulfites are used as a preservative in this food.
硫酸塩 is sulfate (SO₄²⁻), while 亜硫酸塩 is sulfite (SO₃²⁻), with one less oxygen atom.
Compound of 亜硫酸 (sulfurous acid) + 塩 (salt). The prefix 亜 indicates a lower oxidation state compared to 硫酸 (sulfuric acid).