Extraction of Some Ellagic Tannins and Ellagic Acid from Oak Wood Chips (Quercus pyrenaica L.) in Model Wine Solutions: Effect of Time, pH, Temperature and Alcoholic Content

Abstract

The subject of the present work is the study of the influence of pH, temperature, alcoholic content and time on the extraction of some individual ellagic tannins (castalagin, vescalagin, grandinin, roburin D and E) and ellagic acid from oak wood chips (Quercus pyrenaica L.) within model wine solutions. The determination of these compounds by reversed-phase high-performance liquid chromatography (HPLC), after 104 extraction days, enabled us to establish the qualitative and quantitative evolution of each component and the effect of each extraction condition on individual and total ellagic tannins from oak wood chips. Vescalagin and castalagin were the most abundant individual ellagic tannins measured under all extraction conditions. Individual ellagic tannins and ellagic acid increased during the first weeks of extraction, followed by a decrease. Under the extraction conditions examined, temperature was the main factor influencing ellagic tannins and elagic acid evolution. The results suggest that a decrease/degradation of these compounds is less noticeable at low temperatures (12ºC). After 104 extraction days the ellagic tannins content in a model wine solution at 12ºC was higher than the content of ellagic tannins in solutions at 20ºC. On the other hand, the effects of alcoholic content and pH of model wine solutions on the extraction and evolution of the analysed compounds (except for castalagin and vescalagin) seemed to be less important than temperature.

Extraction of phenolics from new oak casks during spirit maturation: impact on spirit colour

“…Moreover, increasing pH enhanced wood fibre swelling (36) and improved the extractability of wood compounds (37). Also, at a pH of 3.1-3.7, Jordao et al (38) highlighted the positive effect on ellagitannin extraction. In spirits, pH ranged from 3.1 to 7.6 (with an average of 4.5) during maturation and pH dropped by 0.6 to 1.8 units (39) owing to the extraction of organic acids (40).…”

Characterisation of Pinotage Wine During Maturation on Different Oak Products

“…Ellagitannins, which were not measured in the present study, are also likely to contribute to the increased TAC R during oak maturation due to their extraction from the oak wood. Ellagitannins have been shown to have high radical scavenging activity (Saint-Cricq de Gaulejac et al, 1998), while the hydrolysis products of ellagitannins, namely ellagic acid (Ivekovic et al, 2005) and gallic acid (Jordão et al, 2005), are also potent antioxidants due to the many available hydroxyl groups. Ellagic tannins are extracted rapidly into a hydro-alcoholic medium, such as wine, followed by a gradual decrease (Jordão et al, 2005).…”

“…Ellagitannins have been shown to have high radical scavenging activity (Saint-Cricq de Gaulejac et al, 1998), while the hydrolysis products of ellagitannins, namely ellagic acid (Ivekovic et al, 2005) and gallic acid (Jordão et al, 2005), are also potent antioxidants due to the many available hydroxyl groups. Ellagic tannins are extracted rapidly into a hydro-alcoholic medium, such as wine, followed by a gradual decrease (Jordão et al, 2005). Changes in other unknown compounds, which are not necessarily phenolic in nature but have been shown to make a large contribution to the wine TAC M (De Beer et al, 2006), cannot be estimated, but contribute to the TAC R of the wine.…”

Differentiation of Wines Treated with Wood Chips Based on Their Phenolic Content, Volatile Composition, and Sensory Parameters

“…These compounds are oak derived and occur in important levels in European oak barrels (Prida and Puech ; Chira and Teissedre , 2013b). They can be hydrolyzed and are soluble in model wine solutions (Jordão and others ), and wines and spirits (Moutounet and others ). Other extractable wood chemicals, which might be impact molecules, include phenolic aldehydes, phenolic alcohols and ethylphenols released via toasting, oak lactones, and furanic compounds (Koussissi and others ).…”