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Grape pomace is a major winery solid residue and several tons are annually produced worldwide. Since it is a valuable source of high value-added compounds, many strategies have been implemented for its valorization. The extraction of bioactive molecules with a broad range of applications is certainly the most investigated topics. In this context, oleanolic acid, a triterpenoid with a relevant biological activity, has been recently detected in grape pomace in remarkable quantities (0.45 mg per gram of fresh pomace). Herein, we report on a selective extraction of oleanolic acid from grape pomace by using dimethyl carbonate (DMC), a recommended green solvent as a better alternative to fossil-based solvents. Chemical–physical properties, Hildebrand's solubility and Kamlet–Abboud–Taft parameters have been considered to select a greener alternative to fossil-based solvents and theoretical calculations have been performed to determine the interaction between DMC and the oleanolic acid. The obtained grape pomace extracts were characterized by means of NMR and LC-MS. DMC allows the recovery of oleanolic acid from grape pomace, due to its weak polarity and poor ability to form H-bonds, with a molar selectivity of 61%, thus promoting the adoption of alternative green and sustainable technologies for biomass residue valorization. Also, DMC was recycled and reused in three consecutive extractions and no significant losses in terms of oleanolic acid extraction yield were detected. [ABSTRACT FROM AUTHOR]

BACKGROUND: Four red wine matrices representing different red wine styles with the same VOCs (volatile organic compounds), were obtained by enriching a bleed wine with increasing amounts of deodorized dry extract obtained from the pressed wine of the same vinification. The release of VOCs was determined by solid phase micro‐extraction‐gas chromatography–mass spectrometry (SPME‐GC–MS), in conditions mimicking those applied during sensory assessments. RESULTS: Results show that even though the perception of the overall odor intensity was not significantly influenced by the matrix, this latter modulated the odor profiles: at rising wine dry extract, fruity, floral odors decreased, while dehydrated fruit, woody‐toasty, vegetal‐earthy notes increased. These changes cannot be fully explained by the observed significant influence of the matrix on the release of VOCs or by their correlations with the considered matrix components (ethanol, residual sugars, phenolics, pH), but findings suggest that perceptual interactions are involved. CONCLUSION: This study could be useful in pressing and blending management for wine aroma quality also considering wine compositional trends under the current climate change context. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: Climate changes have been leading to an excessive synthesis of quercetin (Q) and its glycosides (Q‐Gs) in specific red grape varieties, such as Sangiovese. This has resulted in concentrations overcoming the solubility threshold of Q in wines, with the consequent formation of undesirable precipitates. This study aims at assessing the impact of various factors, including anthocyanins, temperature, nucleation seeds and time, on the precipitation of Q in red wine. Results: The influence of anthocyanins on Q solubility was examined by adding a grape skin extract rich in anthocyanins to a model solution containing 89 μmol L−1 of Q. The data revealed that the solubility of both Q and Q‐Gs increased as a function of the anthocyanin concentration in the model solution. In a subsequent experiment, red wines were stored at two different temperatures (2 and 20 °C), supplemented with Q nucleation seeds, and monitored over a 10‐day period. Notably, after only 3 days of contact with Q seeds at 2 °C, a reduction of over 75% in Q concentration was observed in the supernatant. Among the considered factors, contact with nucleation seeds emerged as the most significant one (P < 0.0001). Conclusion: Q precipitation in red wines is influenced by the presence of anthocyanins in solution, although it is not the sole determinant. The data also suggested that a potential strategy for wineries to mitigate the risk of Q precipitation in bottled wine would be the acceleration of this process by promoting the formation of nucleation seeds. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Copper (II), a vital fungicide in organic viticulture, also acts as a wine oxidation catalyst. However, limited data are currently available on the impact that maximum allowed copper (II) ion doses in wine grapes at harvest can have on aged wine quality. This was the focus of the present study. We investigated the copper (II) effects by producing both white and red wines from musts containing three initial metal concentrations according to the limits set for organic farming. In detail, the influence of copper (II) on fermentation evolution, chromatic characteristics, and phenolic compounds was evaluated. Interestingly, the white wine obtained with the highest permitted copper (II) dose initially exceeded the concentration of 1.0 mg/L at fermentation completion. However, after one year of storage, the copper (II) content fell below 0.2 ± 0.01 mg/L. Conversely, red wines showed copper (II) levels below 1.0 mg/L at the end of fermentation, but the initial copper (II) level in musts significantly affected total native anthocyanins, color intensity, hue, and acetaldehyde concentration. After 12-month aging, significant differences were observed in polymeric pigments, thus suggesting a potential long-term effect of copper (II) on red wine color stability. [ABSTRACT FROM AUTHOR]