Assessing the influence of extraction techniques on the phytochemical composition of green coffee (Coffea arabica) using principal component analysis (PCA) and hierarchical cluster analysis (HCA)

This study aimed to compare different extraction methods to determine their effects on the antioxidant properties and phytochemical composition of green coffee. A total of nine extraction techniques were evaluated based on their impact on extraction efficiency, total phenolic and flavonoid content, and antioxidant activity. Statistical analyses, including Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA), were applied for data interpretation. The findings indicated that the Ultrasonic-Assisted Microwave Extraction (UMAE) method achieved the highest extraction efficiency, along with the greatest total phenolic and flavonoid content and antioxidant activity. Notably, most analytical parameters showed a strong correlation with the first principal component (PC1), which accounted for approximately 80.40 % of the total variance. Hierarchical Cluster Analysis, represented through a heatmap, further confirmed that all parameters associated with the UMAE method consistently exhibited the highest values. Qualitative analysis and Fourier Transform Infrared (FTIR) spectroscopy validated the presence of key phytochemical compounds, including phenols, alkaloids, flavonoids, and aromatic compounds. Furthermore, Gas Chromatography-Mass Spectrometry (GC-MS) analysis identified caffeine as the dominant compound in the extracted samples.