¹H NMR: A Novel Approach To Determining the Thermodynamic Properties of Acetaldehyde Condensation Reactions with Glycerol, (+)-Catechin, and Glutathione in Model Wine

Abstract

As wine oxidizes, ethanol is converted to acetaldehyde, but its accumulation is not predictable, due to poorly characterized reactions with alcohols, SO2, thiols, flavanols, and others. Measurement of these components has been thwarted by equilibria into the other forms during sample preparation. NMR spectra can be taken on intact samples and is thus ideal for this situation. Equilibria of acetaldehyde with glycerol, (+)-catechin, and glutathione were studied separately in model wine solutions at pH 3-4 by (1)H NMR and 2D ((1)H-(1)H) COSY spectra. Glycerol acetals had equilibrium constants between 1.14 ± 0.056 and 2.53 ± 0.043 M(-1), whereas ethylidene-bridged (+)-catechin dimers and glutathione thiohemiacetals had more favorable equilibria: from (3.92 ± 0.13) × 10(3) to (6.13 ± 0.32) × 10(3) M(-2) and from 10.18 ± 0.22 to 11.17 ± 0.47 M(-1), respectively. These data can be used to create accurate measures of acetaldehyde in its various forms and, consequently, offer insight into wine oxidation.

Yeast alter micro‐oxygenation of wine: oxygen consumption and aldehyde production

“…This showed that these four selected heterocyclic acetal alcohols were all well correlated with acetaldehyde. This close correlation also shows that it may be possible to relate the dioxane or dioxolane levels to acetaldehyde levels in wine, as reported recently …”

Enological tannins affect acetaldehyde evolution, colour stability and tannin reactivity during forced oxidation of red wine

“…. After the first two days of oxidation, the quantity of acetaldehyde dramatically decreases, consistently with the involvement in numerous reactions owing to the great reactivity of this electrophile compound (Peterson & Waterhouse, ). Enological tannins determine an increase in the production of acetaldehyde probably owing to the presence of more structures containing O‐diphenols (Danilewicz, ; Waterhouse & Laurie, ) and/or to traces of metal catalysts present as contaminants of enological tannin preparations.…”

Simultaneous determination of diethylacetal and acetaldehyde during beer fermentation and storage process

“…Acetaldehyde in alcoholic beverages can be produced by yeasts and acetic bacteria or from the oxidation reaction of alcohol and phenolic compounds . However, the electrophilicity of acetaldehyde leads to its participation in reversible reactions with various nucleophiles in alcoholic beverages, including alcohols, thiols, sulfur dioxide and flavonoids . In acidic conditions, acetaldehyde reacts easily with ethanol to generate diethylacetal .…”

“…observed the acetaldehyde and acetal from distillation cut, raw liquor and Chinese finished liquor . Aged and micro‐oxygenated wines were monitored in production by sensory analysis or by measuring acetaldehyde . During the brewing process, the determination and quantitative analysis of acetaldehyde could assist in the evaluation of complete and proper fermentation; improper fermentation resulted in reprocessing or dumping of beer.…”

“…Considering that acetaldehyde has no UV‐active or fluorescent groups, HPLC methods have usually used 2,4‐dinitrophenylhydrazine or cysteamine as derivatization reagents. Recently, Peterson and Waterhouse determined the thermodynamic properties of acetaldehyde condensation reactions in model wine using proton nuclear magnetic resonance spectroscopy . Headspace gas chromatography (HS‐GC) has been a useful tool to analyze volatile substances in the food, beverage, environmental, medical and chemical fields.…”