Influence of post-harvest treatments on chemical composition, physicochemical, microstructural, and thermal properties of green specialty coffee beans

This study investigated how modifications to semi-dry (Yellow/Red Honey) and wet-processing (Double Washed, Slow Fermentation) methods impact Coffea arabica L. var. Red Catuai specialty coffee. Results revealed that mucilage retention levels and fermentation conditions dictate a metabolic shift between lipid catabolism and sugar biosynthesis, differentiating the samples. Early, complete removal of mucilage in the Double Washed method hindered organic acid accumulation, resulting in lower titratable acidity compared to Slow Fermentation (146.67 and 193.33 mL NaOH 100 g^-1, respectively). Consecutive fermentation and washing steps decreased total volatiles concentration, particularly alcohols, acids and esters, and triggered bean stress that altered color via enzymatic browning; however, thermal decomposition profiles remained uniform across all treatments. Gas chromatography-mass spectrometry revealed quantitative differences in volatiles, suggesting processing-related changes in microbial metabolic pathways. The findings demonstrate that modifying mucilage amount and fermentation conditions allows the specialty coffee industry to tailor flavor precursors and achieve unique sensory profiles.