As milk constituent is used to be frequently separated in the case of earlier canned coffee (called 'Ring' due to the constituent being attached to the interior wall of cans), cans had to be shaked before drinking, which became almost unnecessary due to the development of emulsifiers.
初期の缶コーヒーは乳成分が分離することがよくあった（缶の内部に付着するため「リング」と呼ばれた）ため、よく振ってから飲用しなければならなかったが、乳化剤の発達により振る必要はほぼ無くなった。