Characterization of key aroma-active compounds in fresh and vacuum freeze-drying mulberry by molecular sensory science methods

Mulberry is prone to rapid deterioration, but its quality can be maintained through vacuum freeze-drying. In this study, the aroma compositions of fresh mulberry (FM) and vacuum freeze-dried mulberry (VFDM) were analyzed through headspace solid-phase microextraction (HS-SPME) and solvent-assisted flavor evaporation (SAFE) coupled with GCxGC-O-TOF-MS. A total of 232 volatiles were detected in FM and VFDM, and the content of volatile compounds in VFDM decreased by at least 21.37 % after drying compared to FM. Additionally, 51 and 50 aroma-active compounds were detected in FM and VFDM, respectively, with 13 aroma-active compounds being identified in FM initially. Based on the aroma extraction dilution analysis (AEDA) results, 14 compounds with high flavor dilution (FD) factors were accurately quantified by GC-MS. The calculated odor activity value (OAV) showed that a total of 12 compounds significantly contributed to the aroma of mulberry. Finally, aroma recombination and omission experimental results showed that (E,Z)-2,6-nonadienal, beta-ionone, hexanal, and (E)2-nonenal were the key aroma-active compounds in FM, whereas (E,Z)-2,6-nonadienal, beta-ionone, (E)-2-nonenal, eugenol and ethyl isovalerate were the key aroma-active compounds in VFDM.