Complex sentence: Those from eastern North America are slowly mildly acrid and caused uncomfortable drying in the mouth, while specimens from Japan, New Zealand, and the USSR produced no sensation in the mouth, but significant constriction and a nauseating taste in the throat.
Split into simpler sentences: Those from eastern North America have a mildly acrid taste that took time to develop, and caused uncomfortable drying in the mouth. In contrast, specimens from Japan, New Zealand, and Russia produced no sensation in the mouth, but caused significant constriction and a nauseating taste in the throat.