Abstract: Objective: A reversed-phase high performance liquid chromatography (RP-HPLC) method was established to simultaneously determine 4 capsaicinoids including capsaicin, dihydrocapsaicin, nordihydrocapsaicin and homocapsaicin in chili peppers. Methods: Capsaicinoids were separated on a Nucleosil C18 column (4.6 mm × 250 mm, 5 μm) using a mobile phase composed of acetonitrile and water through gradient elution at a flow rate of 1.0 mL/min. The detection wavelength was 280 nm. Results: An excellent linear relationship between peak areas and concentrations of 4 capsaicinoids in the range of 1.0 －160.0 μg/mL with correlation coefficients of 0.9965－0.9993 was observed. The precision and stability RSD (%) of this method were lower than 2.7%. The average recovery rates of 4 capsaicinoids was 97% －99% (n＝6). The contents of 4 capsaicinoids in 30 chili pepper varieties revealed an obvious difference. Conclusion: This method has been successfully used to determine 30 chili pepper varieties with stable and reproducible results. Moreover, piquancy taste is obvious when the total content of capsaicin and dihydrocapsaicin is more than 0.1%.

Key words: chili peppers, reversed-phase high performance liquid chromatography (RP-HPLC), capsaicin, dihydrocapsaicin, nordihydrocapsaicin, homocapsaicin