Cyclocurcumin has a strong ability to scavenge ˙OH by its 4′-OH phenolic hydroxyl via a hydrogen-atom transfer mechanism in a physiological environment.

Making use of anthocyanin copigmentation, it is possible to effectively improve color quality and stability of red wines and other foods. This can be done by selecting strong copigments, but a 1-fold experimental screening usually entails a high cost and a low efficiency. The aim of this work is to show how a theoretical model based on density functional theory can be useful for an accurate and rapid prediction of copigmentation ability of a copigment. The present study, concerning the copigmentation between oenin and quercetin under the framework of implicit solvent, indicates that, in these conditions, the intermolecular hydrogen bonds play an important role in the system stabilization. The dispersion interaction slightly affects the structure, energies and UV-Vis spectral properties of the copigmentation complex.

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On the basis of the dispersion-corrected density functional theory, a computational model is proposed to describe the oenin/syringic acid copigmentation and to explore the non-covalent interaction between the anthocyanin and the copigment in the framework of implicit solvent approach. The predicted binding free energy and visible spectrum shift of this copigmentation complex are in accordance with the experimental observations. The used model provides a good structural description of oenin/syringic acid complex and suggests that the intermolecular hydrogen bonding, in which the hydroxyl-rich sugar moiety in oenin plays a key role, may be the determinant for the formation and nature of the copigmentation complex.

In order to analyze the molecular rearrangement of terpenes in wine during aging, the changes in linalool, α-terpineol, nerol, and geraniol in model wine were investigated in the dark at low temperature for 90 days. Headspace-gas chromatograph−mass spectrometer/olfactometry was used for qualitative and relative quantitation of terpenes. Quantum mechanical calculation was used to analyze the Gibbs free energy. The results showed that nerol was converted into D-limonene, terpinolene, linalool, and α-terpineol. Geraniol was converted into β-ocimene, terpinolene, and linalool. Linalool was converted into terpinolene. The conversion rate of nerol to terpinolene was the highest with 5.94%. α-Terpineol was not converted spontaneously into other terpenes due to its lowest Gibbs free energy, indicating that the cyclization and isomerization could occur spontaneously through an exotherm reaction. However, the dehydroxylation of linalool, nerol, and geraniol required an energy source.

A visual and easy-to-implement representation approach of red wine color is proposed in this work. The wine color under standard conditions, called feature color, was reproduced in the form of a circular spot. The feature color was further decomposed into two orthogonal aspects, the chromatic and light–dark components, characterized in the form of chromaticity distribution plane and lightness distribution plane, respectively. The color characterization of wine samples showed that this method well represented the color characteristics and can provide intuitive visual perception of wine color, in a way that is more reliable and convenient than the photographic method. The applications for monitoring the color evolution during winery and laboratory fermentation and the age discrimination of 175 commercial red wines suggest that this visual method is effective for color management and control of wine during fermentation and aging. The proposed method is a convenient way to present, store, convey, understand, analyze and compare the color information of wines.