Abstract: Fourier transform infrared spectroscopy was used to analyze five groups of light-roasted coffee bean samples from different producing areas and different altitudes. The main components of the samples were analyzed according to the infrared spectral characteristic peaks of functional groups. In order to further analyze the compositional differences of the five groups of samples， the original spectra were subjected to second-order derivative processing. The average deviation analysis method was established based on the theory of cluster analysis, and the average deviation between the five groups of samples was calculated and analyzed. The results show that the infrared spectral characteristic peaks of the five groups of samples have similar peak shapes, that is, the main components are the same, the average deviation from the infrared spectrum is positively correlated with the altitude difference of the producing area. The research results provide identification basis for analyzing producing areas and the altitude of the coffee bean, and provide certain reference value for the study of infrared spectrum.

Key words: Fourier transform infrared spectroscopy, mean deviation method, cluster analysis, coffee bean