Olfactory Impact of Terpene Alcohol on Terpenes Aroma Expression in Chrysanthemum Essential Oils

Aroma Perception of Rose Oxide, Linalool and α-Terpineol Combinations in Gewürztraminer Wine

Cis-Rose oxide was found to be an important chiral compound in Gewürztraminer wine, with an enantiomeric ratio range from 76 to 58%. The enantiomeric ratio showed an important influence on white wine aroma when other monoterpenes were present. The aim of this study was to evaluate rose oxide at different ratios and changes to aroma perception, and the interaction of rose oxide with linalool and α-terpineol. A wine model was made based on Gewürztraminer wine. Twelve models were created with different ratios of rose oxide and concentrations of linalool and α-terpineol. Triangle tests, check-all-that-apply (CATA) and descriptive analysis were used to evaluate the aroma of the wines. Results show that the rose oxide ratios of 70:30 and 65:35 were statistically different. Additional descriptive analysis showed that the ratios altered aroma when linalool and α-terpineol were at low and medium concentrations. At high concentrations, linalool and α-terpineol masked any influence from rose oxide. Understanding how monoterpenes alter aroma perception of white wine when at different combinations and concentrations is important to achieving desired wine qualities and helps provide information on how flavor chemistry results can be interpreted without having to run sensory analysis.

A New Classification of Perceptual Interactions between Odorants to Interpret Complex Aroma Systems. Application to Model Wine Aroma

Although perceptual interactions are usually mentioned and blamed for the difficulties in understanding the relationship between odorant composition and aromatic sensory properties, they are poorly defined and categorised. Furthermore, old classifications refer mainly to effects on the odour intensity of the mixture of dissimilar non-blending odours and do not consider odour blending, which is one of the most relevant and influential perceptual interactions. Beginning with the results from classical studies about odour interaction, a new and simple systematic is proposed in which odour interactions are classified into four categories: competitive, cooperative, destructive and creative. The first categories are most frequent and display a mild level of interaction, being characterised mostly by analytical processing. The last two are less frequent and activate (or deactivate) configurational processes of object recognition with deep effects on the quality and intensity of the perception. These interactions can be systematically applied to interpret the formation of sensory descriptors from the odorant composition, suggesting that qualitatively the system works. However, there is a lack of quantitative data to work with odour intensities reliably, and a pressing need to systematise the effects of creative interactions.

Molecular cloning and functional characterization of a two highly stereoselective borneol dehydrogenases from Salvia officinalis L

Enzymes for selective terpene functionalization are of particular importance for industrial applications. Pure enantiomers of borneol and isoborneol are fragrant constituents of several essential oils and find frequent application in cosmetics and therapy. Racemic borneol can be easily obtained from racemic camphor, which in turn is readily available from industrial side-streams. Enantioselective biocatalysts for the selective conversion of borneol and isoborneol stereoisomers would be therefore highly desirable for their catalytic separation under mild reaction conditions. Although several borneol dehydrogenases from plants and bacteria have been reported, none show sufficient stereoselectivity. Despite Croteau et al. describing sage leaves to specifically oxidize one borneol enantiomer in the late 70s, no specific enzymes have been characterized. We expected that one or several alcohol dehydrogenases encoded in the recently elucidated genome of Salvia officinalis L. would, therefore, be stereoselective. This study thus reports the recombinant expression in E. coli and characterization of two enantiospecific enzymes from the Salvia officinalis L. genome, SoBDH1 and SoBDH2, and their comparison to other known ADHs. Both enzymes produce preferentially (+)-camphor from racemic borneol, but (-)-camphor from racemic isoborneol.