Discrimination of several robusta organic coffees from Sumatra Indonesia with different origins using UV spectroscopy and principal component analysis

Abstract

Comparing to non-organic coffee, organically grown coffee has been regarded to be healthier at a more expensive price. Recently, in Sumatra, Robusta organic coffee is becoming more popular. However, it is difficult to assess the origin of organic ground roasted coffee resulting in frequent mislabeling incidence in the market. In this research, an effort to discriminate Robusta organic coffee from different origins was evaluated using ultraviolet (UV) spectroscopy and principal component analysis (PCA). A total of fifty samples of ground-roasted organic coffee from two origins in Sumatra Indonesia (Lampung and Bengkulu) was used. The samples were extracted using hot distilled water, filtered, and diluted with distilled water (1:70 volume/volume). UV spectra were measured in the range of 220-400 nm with 1 nm of the resolution using a benchtop UV-Vis spectrometer. Principal component analysis (PCA) was applied for original and preprocessed spectral data in the range of 220-400 nm. Using the first and the second principal components (PC1 and PC2) using preprocessed spectra resulted in a distinct cluster between Lampung and Bengkulu organic coffee samples. This result showed the effectiveness of PCA in differentiating between the organic Robusta coffee from different origins (Lampung and Bengkulu).