Multivariate analysis of FT-IR, bioactive compounds, and antioxidant activity in coffee pulp (Coffea arabica var. Catimor): combined effects of ripening stage and drying method

Abstract

[EN] Coffee pulp, a nutrient-rich by-product, holds untapped nutraceutical potential but requires postharvest optimization. This study evaluated how ripening stage and drying method jointly modulate bioactive compounds in Coffea arabica var. Catimor pulp. FT-IR spectroscopy, HPLC-DAD, and antioxidant assays, coupled with multivariate analysis, revealed drying as the primary driver of compositional changes. FT-IR PCA (97.5 % variance in PC1) distinguished freeze-dried from thermally treated samples, while key VIP bands associated with lignin and structural carbohydrates, together with bioactive profiles (chlorogenic acid, ABTS, caffeine), revealed thermal degradation as a unifying process shaped by ripening stage. Drying x ripening effects modulated all variables except caffeine, which declined with ripening. Thermal treatments reduced phenolics, DPPH, trigonelline, and 5-CQA, with greater losses in overripe pulp. ABTS increased with roasting, while peak levels occurred in ripe freeze-dried samples. These results underscore the need for ripening-specific drying protocols to optimize coffee pulp's functional quality.