There was a certain period of time during which hopes were placed upon instant coffee and coffee extracts that generate no grounds as raw materials , but they never became mainstream due to their being inferior to the drip method in quality . かすが発生しないインスタントコーヒーやコーヒーエキスなどに原料としての期待が寄せられた時期もあったが、品質の点でドリップ方式に劣るため主流になることはなかった。