Oxygen and SO₂Consumption of Different Enological Tannins in Relationship to Their Chemical and Electrochemical Characteristics

Abstract

The oxidative behavior of five commercial enological tannins of different sources (tea, grape marc, grape seed, untoasted oak, and toasted oak) was investigated in model wine solutions in the presence or absence of SO 2 . Solutions of the tannins were also analyzed for total phenolics, methyl cellulose precipitable tannins, high-performance liquid chromatography, and linear sweep voltammetry. Tea and oak-derived tannin solutions were characterized by the highest oxygen consumption rates, with oak-derived tannins exhibiting the highest oxygen consumption rates per milligram of phenolic material present. Linear sweep and derivative voltammetry parameters were well-correlated with oxygen consumption rates, whereas total phenolics or total tannins were not. All tannins were associated with consumption of SO 2 upon reaction with oxygen, with the lowest rate of SO 2 lost per milligram of O 2 reacted being observed for oak tannins.

Effect of Different Enological Tannins on Oxygen Consumption, Phenolic Compounds, Color and Astringency Evolution of Aglianico Wine

“…Ellagitannins are obtained from oak and chestnut wood [ 6 ], while gallotannins are mainly from galla and tara nuts [ 7 ]. Tea tannins, well known for their beneficial bioactivities [ 8 ], were also tested in model wine solutions by Ugliano, Slaghenaufi, Picariello and Olivieri 2020 [ 9 ], who showed that they were capable of rapidly consuming oxygen, although this is associated with an increased decline in the SO 2 content.…”

“…In regard to enological tannins, Ugliano, Slaghenaufi, Picariello and Olivieri [ 9 , 18 ] ascertained that different types of commercial tannins increase the oxygen consumption rate (OCR) and affect sulfur dioxide during an oxidative process in model wine solution. Moreover, Rinaldi and Moio [ 19 ] showed that the addition of different types of enological tannins affects the astringency and determines different astringency subqualities in Sangiovese wine.…”

Electrochemical Approaches for Rapid Characterization of Oxidizable Compounds in Different Oak Alternatives

“…Strong and highly significant correlations were found for both total phenolics and total tannins when total AUC of linear sweep votammograms was considered (Figure 2), with regression equations of y = 0.0002x − 183.58 for total phenolics and y = 0.0001x − 155.52 for total tannins respectively. Previous studies have indicated that AUC of either total raw voltammograms or subsections thereof are well correlated with wine values for total phenolics [20] as well as with total phenolics or total tannins values of commercial tannin powders [11,21]. Other studies have shown that the phenolic content of oak extracts is highly representative of their antioxidant capacity [17] as well as of their ability to consume oxygen during wine storage [7,11].…”

“…Chemical and electrochemical analyses. Total phenolic index (TPI) and methyl cellulose precipitable tannins (MCPT) were determined as previously described [11]. Briefly, at the end of the extraction period, OAs extracts were centrifuged, and TPI was determined spectrophotometrically using the Folin-Ciocalteau reagent, with results being expressed as mg/L eq.…”

“…They can enrich the wine with the same substances that are released during oak barrel aging, in particular aroma compounds, but also ellagitannins and other non-volatile phenolics [7,8]. The latter point is of great importance as ellagitannins play a central role in wine aging chemistry, affecting wine antioxidant capacity [9,10], ability to consume oxygen [7,11], and SO 2 consumption by oxidation reactions [11], and they deeply influence wine mouthfeel [5,8]. However, phenolic content of oak varies largely depending on geographical and biological origin of the wood, its age, and its anatomy [3], as well as by cooperage, in particular toasting.…”