Abstract: The thioglucosides (TGD) existed in the rhizome of Armoracia lapathifolia Glib were the predecessors of the essential oil of Armoracia lapathifolia Gilib,being hydrolyzed under certain conditions.The effects of time,temperature,pH and ascorbic acid added on the hydrolysis of TGD were determinated.The optimum hydrolytic conditions for the essential oil from TGD existed in Armoracia lapathifolia Gilib.Were:time,120 minutes;temperature,65℃;pH,4.0 and ascorbic acid,2mg/g.The essential oil was analyzed by GC/MS.Eighteen constituents were identified,which represent 95.15% of the whole oil.The major components characterized in the oil were:allyl isothiocyanate (31.83%),the highest among all constituents,4-pentenyl isothiocyanate (26.24%).The 3-butenyl isothiocyanate (3.10%),phenyl isothiocyanate (3.10%),phenyl isothiocyanate (1.87%) and benzyl isothiocyanate (1.65%) were only found in Chinese horseradish.

Key words: Armoracia lapathifolia Gilib Thioglucosides GC/MS Isothiocyanate