Identification of characteristic aroma volatiles of Ningxia goji berries (Lycium barbarum L.) and their developmental changes

As the major commercial goji berry in the world, Ningxia goji (Lycium barbarum L.) berries are generally used as a traditional herbal medicine and functional food. This berry was appreciated by consumers due to its unique aroma. However, the berry's characteristic aroma compounds are still unknown. Volatiles of Ningxia goji berries (Lycium barbarum L.) were characterized by gas chromatography–mass spectrometry (GC–MS), and their characteristic aroma components were identified by aroma dilution analysis (AEDA) and gas chromatography–olfactometry (GC–O). The developmental changes in these fruits were also monitored. Among 56 volatile compounds identified, hexanal and (E)-2-hexenal predominated in the Ningxia goji berries, which accounted for 70–94% of the total volatiles. Flavor dilution factors (FD) of 17 identified compounds were 27, but only 15 compounds had more than one odor activity value (OAV). The combined results of the GC–O and OAV revealed that hexanal, (E)-2-hexenal, nonanal, isoamylol, 1-hexanol, 1-octen-3-ol, hexyl acetate, methyl salicylate, ethyl octanoate, o-cymene, d-limonene, linalool, β-cyclocitral, β-elemene, and 2-pentylfuran were the characteristic aroma volatiles in the Ningxia goji berries. During fruit development, the content of hexyl acetate, linalool, and 2-pentylfuran increased remarkably. Conversely, β-cyclocitral and β-elemene increased at the early stage, but decreased with other characteristic compounds. We first identified the characteristic aroma volatiles of the Ningxia goji berries and determined the dynamic changes of the volatiles during development.