Authentication of organic Lampung robusta ground roasted coffee by UV-visible spectroscopy and PLS-DA method

Abstract

In this research, a potential application of UV-visible (UV-Vis) spectroscopy combined with partial least squares-discriminant analysis (PLS-DA) method to discriminate Lampung robusta coffee with different fertilizer treatment was evaluated. The fully red ripened coffee beans were selectively harvested by hand from coffee plantation located in Lampung Barat of Lampung province from two different fertilizer treatments: chemically fertilized and organically fertilized. A number of 200 ground roasted coffee samples of each treatment (1 gram of each samples) was used as samples, respectively. The all coffee samples were extracted using hot distilled water. The aqueous coffee samples were pipetted into 10 mm of cuvette and the spectral data was obtained using a UV-Vis spectrometer in the range of 190-1100 nm. Principal component analysis (PCA) and PLS-DA method was used as unsupervised and supervised classification methods to discriminate the organic and non-organic coffee. The results showed that using the first two principal components (PCs), a clear separation between organic and non-organic coffee samples was achieved using modified spectral data in the range of 230-450 nm. The classification of organic and non-organic coffee using PLS-DA method resulted in high accuracy both for calibration and prediction steps. The overall result showed that UV-visible spectroscopy combined with PLS-DA method could be used as a low-cost, relative fast and green method to discriminate between organic and non-organic Lampung robusta ground roasted coffee.