harsh or corrosive in tone; "an acerbic tone piercing otherwise flowery prose"; "a barrage of acid comments"; "her acrid remarks make her many enemies"; "bitter words"; "blistering criticism"; "caustic jokes about political assassination, talk-show hosts and medical ethics"; "a sulfurous denunciation"
is anything sour, bitter or sharp - cutting, caustic, acid, mordant, barbed, prickly, biting, pointed. The opposite flavor would be mild, sweet, or honeyed.