Flavor improvement in enzymatically hydrolyzed Citrus Huyou peel residues: based on sensory and multi-omics analysis

Peel residues of Citrus Huyou (Citrus aurantium 'Changshanhuyou') were byproducts of juice production. They were rich in free and glycosidically bound flavor compounds but remained underutilized. We designed an enzymolysis process to enhance flavor release. The conditions were optimized by single-factor and response surface methodology. Sensory evaluation confirmed that the optimized enzymolysis increased desirable citrus, floral, and sweet notes, while reducing bitterness and off-odors of Huyou residue extracts. Multi-omics analysis (GC-IMS, GC × GC-TOF-MS, UPLC-MS/MS) elucidated the variation of compounds related to the flavor improvement. Twenty-three key differential compounds were identified among four groups. The aroma contributions of terpenes were markedly enhanced. Enzymolysis significantly increased six aldehydes, eighteen esters, and six alcohols. The liberation of geranic acid from glycosidic precursors was reported for the first time in Huyou. This study provided new theoretical and methodological insights for upcycling peel residues to impart a richer and more harmonized flavor to Huyou-based products.