Processing- and fermentation-induced changes in chemical and volatile profiles of coffee cherry pulp tea

Abstract Coffee cherry pulp (CCP), a major by-product of wet coffee processing, remains underutilized in food applications despite its phenolic richness. In this study, CCP was prepared as a tea and systematically evaluated under different extraction solvents, drying methods, and brewing conditions to establish a food-relevant substrate. The selected CCP tea was subsequently fermented with Lactiplantibacillus plantarum , and fermentation-associated changes in chemical and volatile profiles were examined. Extraction solvent and brewing conditions significantly influenced phenolic content and antioxidant activity of CCP tea. During fermentation, total phenolic and flavonoid contents increased at 24 h and declined with extended fermentation, accompanied by a gradual decrease in antioxidant activity. Untargeted metabolomic analysis revealed distinct compositional differences between CCP tea and its fermented counterpart, including higher signal intensities of amino acids and other nitrogen-containing metabolites, alongside decreased levels of hydroxycinnamate esters and flavonoid glycosides such as chlorogenic acid. HS-SPME–GC/MS analysis further demonstrated fermentation-associated shifts in volatile composition, characterized by reductions in aldehydes and ketones and increases in phenols, esters, organic acids, and furans. Overall, fermentation with L. plantarum was associated with coordinated changes in both small-molecule composition and volatile profile, highlighting CCP tea as a fermentable substrate under food-relevant processing conditions. These findings provide a compositional basis for the further development and evaluation of fermented CCP-based beverages.