Dynamic changes of volatile compounds during coffee-grounds beer fermentation with different yeast strains: An integrated HS-SPME-GC/MS, electronic tongue and electronic nose analysis

) through an integrated multi-omics approach. Electronic tongue and nose analyses revealed distinct bitter, umami, and sulfurous notes, with Strain E showed the most balanced sensory profile. HS-SPME-GC-MS analysis detected 460 volatile compounds, showing increasing trends during fermentation. Nine key aroma-active compounds (ROAV>1) were characterized, including ethyl butyrate, guaiacol, and 2,3-diethyl-5-methylpyrazine. Notably, guaiacol contribution decreased markedly in late fermentation with strains U and D, may indicate potential time-strain synergistic effects. Metabolic trajectory analysis revealed distinct pathways among the yeast strains: Strain R favored phenolic-ester-heterocyclic compounds, Strain E predominantly produced ester‑sulfur-heterocyclics, Strain U formed aromatic aldehydes via phenylalanine metabolism, and Strain D showed acid-ester‑sulfur conversion.Yeast selection and fermentation duration significantly influenced physicochemical properties. These findings provide new insights for valorizing coffee processing byproducts.