Understanding the release and metabolism of aroma compounds using micro-volume saliva samples by ex vivo approaches

- Aroma compounds are affected by human saliva as a function of their structure.
- Whole saliva exerts a higher effect than clarified saliva on aroma release.
- Differences in aroma release among individuals are related to saliva composition.
- The transformation of the affected compounds by saliva was proven.
- LLE-GC/MS data strongly suggest that this transformation is of an enzymatic nature.

This study investigated the behaviour of key aroma compounds in the presence of human saliva (200 μL) from different individuals (n = 3) submitted or not to centrifugation (whole vs clarified saliva). HS-GC results showed that human saliva strongly decreased the release of carbonyl compounds (aldehydes and ketones). This effect was dependent on i) the structure of the aroma compounds and ii) the saliva composition. Whole saliva exerted a higher effect than clarified saliva on aroma compounds. Moreover, this effect was individual-dependent and related to the total protein content and the total antioxidant capacity of saliva. HS-SPME and LLE-GC/MS analyses revealed that metabolism of the compounds by salivary enzymes was involved. This observation indicates that some aroma compounds could be metabolized in the oral cavity in an individual manner, which could have implications for aroma perception (e.g., formation of new metabolites with different odor thresholds and qualities) and/or organisms' health status (e.g., compound detoxification).