Study on the interaction of tannins and salivary proteins affecting wine aroma volatility: Static HS-SPME and molecular dynamics simulation approaches.

The interaction between tannins and salivary proteins might affect intraoral aroma release during wine consumption. In this study, the influence and underlying mechanism of interactions between EGCG and IB5 (salivary proline-rich protein) on wine aroma compounds was analysed by static HS-SPME in vitro and molecular dynamics (MD) simulation. The interaction between IB5 and EGCG could significantly reduce the volatility of most aroma compounds in the model wine by 20 %-70 % (p < 0.05). MD simulations indicated that the energy received by aroma compounds in the mixed system was more pronounced. In addition, the decline rate of rational correlation functions (RCF) of aroma compounds in the mixed system was obviously slower. The analysis of the independent gradient model (IGM) indicated that aroma compounds combined with aggregates of IB5 and EGCG through hydrogen bonds and van der Waals forces. The effect of the interaction between EGCG and IB5 on aroma compounds was confirmed by the volatility and molecular computational simulation. Overall, the results enhance the understanding of the mechanisms affecting retronasal aroma release during wine consumption.

Impact of tannins on intraoral aroma release and retronasal perception, including detection thresholds and temporal perception by taste, in model wines.

Tannins, as an important wine nonvolatile matrix component, can cause astringency, which may affect aroma perception through cross-modal interactions during wine consumption. An aromatic model wine with tannin extracts was evaluated by intraoral aroma release and sensory analysis after wine spitting. Overall, tannin extracts could significantly decrease all initial aroma release, while they could not reduce most aroma release at 150 s after wine spitting. Regarding the sensory evaluation results, the retronasal detection threshold of most aromas increased. The temporal aroma intensity showed a significant decrease at early time points and was almost unaffected at later time points. In addition, temporal dominance of sensation (TDS) curves revealed that the presence of astringency could reduce the dominant time of most aromas. Therefore, although there was good consistency between instrumental analysis and sensory evaluation, the effect of astringency induced by tannins on retronasal perception cannot be ignored.

Influence of tannins, human saliva, and the interaction between them on volatility of aroma compounds in a model wine.

During wine drinking, aroma release is mainly impacted by wine matrix compositions and oral physiological parameters. Notably, tannins in wine could interact with saliva protein to form aggregates which might also affect the volatility of volatiles. To explore tannins, saliva, and the interaction between them on the volatility of volatiles, the volatility of 16 aroma compounds in the model wine mixed with the commercial tannin extracts, human saliva, or both respectively, was evaluated in vitro static condition by using HS-SPME-GC/MS. The volatility of aroma compounds with high hydrophobicity or benzene ring appeared to decrease more when increasing the tannin levels. Specifically, the volatility of ethyl octanoate, ß-ionone, and guaiacol was decreased more than 20% by adding 2 g/L tannin extract. The addition of human saliva could significantly inhibit volatility of most aroma compounds in the model wine. Furthermore, the volatility of most aroma compounds in the mixture of tannins and human saliva was significantly lower than the control or the sample which were added with tannins or human saliva individually. The volatility of some aroma compounds in the mixture of the tannin and saliva was only around 50% or less, relative to the control. Two-way ANOVA analysis showed that there was a synergistic effect between tannin and saliva on decreasing the volatility of most aroma compounds (p < 0.05). Overall, understanding the effect of key factors such as tannins and saliva on volatility of volatiles could help to understand the sophisticated retronasal perceptions during wine tasting. PRACTICAL APPLICATION: The outputs of this research will be helpful in understanding the impact of tannins on retronasal aroma release during wine tasting. It might promote the control of tannins in the viticulture and brewing process to improve the retronasal perception of wine aroma.

Aroma release during wine consumption: Factors and analytical approaches.

During wine consumption, aroma compounds are released from the wine matrix and are transported to the olfactory receptor in vivo, leading to retronasal perception which can affect consumer acceptance. During this process, in addition to the influence of the wine matrix compositions, some physiological factors can significantly influence aroma release leading to altered concentrations of the aroma compounds that reach the receptors. Therefore, this review is focused on the impact of multiple factors, including the physiology and wine matrix, on the aroma released during wine tasting. Moreover, to reflect the pattern of volatiles that reach the olfactory receptors during wine consumption, some analytical approaches have been described for in vitro and in vivo conditions.

Characterization of the Key Aroma Compounds in Marselan Wine by Gas Chromatography-Olfactometry, Quantitative Measurements, Aroma Recombination, and Omission Tests.

Key odorants of red wine made from the hybrid grapes of Marselan (Vitis vinifera L.) were isolated by solid-phase extraction (SPE) and explored by gas chromatography-olfactometry (GC-O) analysis. Application of aroma extract dilution analysis (AEDA) revealed 43 odor-active compounds, and 31 odorants among them were detected with flavor dilution (FD) factors ranging from 9 to 2187. Comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (GC × GC-TOF-MS) were exploited to quantitate the aroma-active compounds with FD ≥9. The identification indicated ß-damascenone as having the highest FD factors, followed by eugenol, 2,3-butanedione, citronellol, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, phenethyl acetate, guaiacol, and 2-methoxy-4-vinylphenol. A total of 21 compounds were found to have odor activity values (OAVs) >1.0. Aroma reconstitution validation experiments showed a good similarity of blackberry, green pepper, honey, raspberry, caramel, smoky, and cinnamon aroma attributes between the original Marselan wine and the reconstructed wine. In addition, omission tests were carried out to further determine the contribution of odorants to the overall aroma.