Characterization of Robusta Bengkulu Coffee from Possible Mixings Using Combination of FTIR Spectroscopy and Chemometric

This study aimed to identify the purity of coffee in the market of Bengkulu City using a combination of FTIR spectroscopy and chemometric techniques for authentication and quality control. The experimental design included variables such as pure coffee, roasted corn, and roasted rice, roasted corn mixed coffee (50% w/w), coffee mixed with roasted rice (50% w/w), and 18 samples of commercial coffee. In addition, each variable was made with three replications. The FTIR spectrum results of coffee, roasted corn, and roasted rice powder showed an almost similar pattern. PCA analysis with the Unscrambler X program indicated that the values of PC-1 and PC-2 could describe 97% of the total variance, with PC-1 = 91%; and PC-2 = 6%. Based on PC-1, pure coffee is on the positive side, while mixed ingredients such as corn and rice are on the negative. Plotted samples of commercial coffee on pure coffee and mixed samples obtained PC-2 and PC-1 values of 95% with PC-1 = 87%, and PC-2 = 8%. From the plotting, it can be concluded that 1 out of the 18 samples was mixed with corn or rice but the concentration of the mixture is unknown.