Abstract: The bitter-tasting compounds of essential oils from Zanthoxylum schinifolium Sieb.et Zucc grown in Hanyuan of Sichuan province, Anshun of Guizhou province (and its fractions separated by vacuum hydrodistillation) and Jiangjin of Chongqing municipality, and from Zanthoxylum bungeanum Maxim. grown in Hancheng of Shaanxi province were analyzed by sensory evaluation and GC-MS. A total of 20 essential oils from different species and geographical localities were subjected to evaluation of their bitterness thresholds and identification of bitter-tasting components and the results were verified by correlation analysis. The bitter-tasting components identified were further validated by addition of suspected bitter compound standards to fraction 1 of the essential oil of Anshun-grown Zanthoxylum schinifolium Sieb.et Zucc. Results showed that the bitterness threshold of essential oil varied among different Zanthoxylum species, with Zanthoxylum schinifolium Sieb.et Zucc being lower than Zanthoxylum bungeanum Maxim. The essential oil of Anshun-grown Zanthoxylum schinifolium Sieb.et Zucc was separated into four fractions with different bitterness thresholds. Correlation analysis of bitterness threshold with alcohols (linalool), ketones and their mixtures indicated that the bitterness had a highly significant correlation with ketones and a significant correlation with alcohols and that both classes of compounds synergistically contributed to the bitterness. High concentrations of alcohol gave bitter taste to the essential oil. Low concentrations of ketone or in a mixture with alcohol dramatically reduced the bitterness threshold of the essential oil.

Key words: Zanthoxylum essential oils, bitter-tasting components, gas chromatography-mass spectrometry (GC-MS), statistical analysis, alcohol and ketone