NMR-Based Tastant Polymer Interaction Studies and the Influence on the Taste Perception of Red Wine

Abstract

Using a quantitative 1H NMR-based approach, molecular interactions between key taste active compounds and high-molecular-weight (HMW) polymers were directly investigated in red wine. Analysis of qualitative and quantitative 1H NMR spectra over time allowed a distinction of three interaction scenarios: (i) no interactions for flavon-3-ol glycosides, ellagitannins, carbohydrates, and amino acids; (ii) changes in the chemical shift to lower frequencies for flavan-3-ols and phenolic acid ethyl esters; and (iii) changes in the chemical shift to higher frequencies for phenolic acids, organic acids, inorganic salts, and alditols. Additionally, using liquid chromatography-tandem mass spectrometry (LC-MS/MS), quantitative 1H nuclear magnetic resonance (qHNMR), and high-performance ion chromatography (HPIC), a taste reconstitution model of Primitivo red wine was established for the first time. Human sensory experiments with the new taste recombinant and different HMW fractions demonstrated the influence of the tastant polymer interactions on the sour and salty taste perception of red wine and the intrinsic bitter and astringent taste of the polymers. Further, the influence of the molecular weight cutoff (MWCO) of the polymers and the pH value on the tastant polymer interactions was analyzed. Especially, the HMW fractions 30–50 kDa and >50 kDa caused strong shifts to lower and higher frequencies, respectively. NMR-based interaction studies at different pH values revealed a maximum of interactions at pH 4.0. Based on these results, flavor changes in red wine caused by tastant polymer interactions can be predicted on a molecular level in the future.

Investigating the Role of Odorant–Polymer Interactions in the Aroma Perception of Red Wine: A Density Functional Theory-Based Approach

“…Furthermore, NMR experiments on binary complexes confirmed the prevailing interaction patterns predicted by DFT-based pair calculations. Moreover, the in-depth characterization of NCIs achieved in this study extends and corroborates findings in studies on the aroma perception and taste of red wine, where specific segments of HMW polymers have been shown to exhibit π–π interactions with pyrazines, as well as further NCIs with lactones and acids while demonstrating no interactions with alcohols.…”

“…As recently shown for interactions between odorants, tastants, and polymers in red wine, compound classes with similar structural features show similar interaction behavior with red wine polymers in NMR and sensory experiments. , In detail, four different NMR interaction types could be investigated for key red wine odorants: no interactions, shielding effects, deshielding effects, and π–π interactions . To establish a correlation of the DFT-based binding affinities in terms of structure–activity relationships between the chemical nature of odorants and the effects on the perception of these odorants, human sensory experiments with odorants and selected polymer segments were carried out.…”

“…For chemical structural formulas of polymer segments and aroma compounds, see the Supporting Information in Figures S1 and S2, respectively. The set of aroma compounds is selected based on the pronounced interaction characteristics in NMR experiments, , and 2-methylpropanoic acid is included for comparison with 3-methylbutanoic acid to evaluate the influence of the hydrocarbon chain. The selected segments are structural building blocks of HMW polymers and representatives of the polymer substance classes .…”

“…Recently, the influence of interactions of aroma and taste compounds with polymers on aroma perception has been elucidated by combining human sensory experiments with NMR-based approaches. , The study aimed to determine the key odorants in Primitivo red wine, demonstrated the effect of aroma-binding by red wine polymers through human sensory experiments, and developed a direct 1 H NMR-based analysis of odorant–polymer interactions that have been shown to influence the aroma profile. The experimental results demonstrated that the polymers exhibit a strong propensity for NCIs with lactones, aldehydes, and acids, with particular emphasis on π–π interactions with phenols and pyrazines.…”

New Insights into the Production of Assyrtiko Wines from the Volcanic Terroir of Santorini Island Using Lachancea thermotolerans

“…Based on our results, the increase of total acidity provoked by L. thermotolerans was not noticed by any of the two panels of experts, showing that 1 g/L of lactic acid does not have a significant impact on lactic or acidity perception. This result is in accordance with a previous study on the role of compound interactions on red wine taste perception, where a concentration of more than 1.4 g/L of lactic acid can contribute to a sour taste of wine [70]. Nevertheless, the expert panel of Santorini seemed to discriminate the acid sensation based on acid composition and not on total acidity, as they found the wines with less malic acid and more lactic acid to be less acidic.…”