Biotransformation of green coffee beans by Aspergillus oryzae

Green coffee beans (GCB) (Coffea arabica L.) contain a mixture of phenolic compounds with proven antioxidant activity. In this study, solid-state fermentation of GCB was carried out by Aspergillus oryzae for 24, 36, and 48 h. After biotransformation, it was performed an extraction using a hydroethanolic solution. High performance liquid chromatography (HPLC) and ultra-high-performance liquid chromatography coupled to mass spectrometry with time-of-flight analyzer (UPLC-MS-Q-TOF) were used for chemical characterization and phytochemical quantification of the extracts. The non-biotransformed and biotransformed (24 h) GCB extracts presented similar chemical profiles. The biotransformation of (36 h) CGB revealed a reduction of 5-CQA concentration accompanied by a significant increase of caffeic, quinic, citric, protocatecuic, 3-caffeoylquinic and 4-caffeoylquinic acids, two dicafeoilquinic acid isomers, and caffeine; it was also observed the formation of theophylline; and the reduction of trigonelline. Coffee biotransformation for 48 h promoted almost total degradation of phenolic compounds.