Anthocyanin Addition Alters Tannin Extraction from Grape Skins in Model Solutions via Chemical Reactions

Abstract

Condensed tannin extraction and stable color formation are two of the cornerstones of red wine production. Without condensed tannin, red wine would lack the tactile feeling of astringency, and without the formation of modified pigments, it would lack color stability for long-term aging. To understand how malvidin-3,5-diglucoside interacts with condensed tannin under nonoxidative conditions, an experiment was designed conducting model-wine skin extractions of Sauvignon blanc grapes harvested at various dates of maturity. Monomeric malvidin-3,5-diglucoside was isolated from color concentrate and added during these extractions. Following a 72 h extraction, solutions were evaluated for recovery of monomeric anthocyanins, skin tannin concentration, skin tannin extractability, and impact of anthocyanins on condensed tannin size. Anthocyanins showed a significant impact on the extraction of flavan-3-ol material in the early stages of ripening that declined in the latter stages of ripening. Furthermore, anthocyanins significantly decreased the size of the condensed tannin extracted. These results suggest that anthocyanins are not only enhancing the extractability of condensed tannin but also readily incorporating into the polymeric material, leading to a decrease in the average molecular mass of the condensed tannin polymer. The extent of reaction in 72 h suggests that the rate of interflavan bond cleavage may be higher than previously reported and merits closer scrutiny.

Effect of applied shading during fruit ripening on tannin structure–activity relationships of grape skin extracts

“…5. There are similarities and differences to previously published work 15,38 . The relationship between the molecular mass of tannins and tannin activity is the same as that of other work; however, there are differences in subunit composition correlations and pigmentation.…”

“…These results disagree with some previously published work showing increases in extractability near the commercial harvest. A possible explanation for this is variability in berries and extraction techniques used 38 . In this experiment two different samples were extracted separately; in that experiment a sequential extraction technique was used that may provide a better understanding of changes in tannin extractability.…”

“…In that work it was shown that increasing anthocyanins led to decreasing tannin size during the experiment. Although that experiment gave insight into how anthocyanins may impact the size distribution of tannin, it was conducted on a white grape variety 38 . Furthermore, work looking at tannin using model wine extractions by acid catalysis may misrepresent the tannin by reasons discussed below.…”

“…Although both average molecular mass by GPC and mDP by phloroglucinolysis are measures of polymer size, mDP is a calculation based on the ratio of extension and terminal flavan‐3‐ol subunits in the tannin polymer. If a terminal subunit was not a flavan‐3‐ol subunit (e.g., anthocyanin), it would lead to an inaccurate accounting of terminal subunits analytically and would therefore lead to a false high in reported mDP 38 . Anthocyanins which have been incorporated as terminal subunits into the proanthocyanidin structure have been shown to have a lower proclivity to cleave under acidic conditions due to the flavylium form having a positive charge.…”

Investigating the Role of Odorant–Polymer Interactions in the Aroma Perception of Red Wine: A Density Functional Theory-Based Approach

“…During red wine fermentation and aging processes, biochemical reaction precursor compounds such as (+)-catechin and p -coumaric acid are incorporated into different polymers with molecular weights ranging from 5 kDa to more than 50 kDa. , These high-molecular-mass polymeric polyphenols (HPPCs) , consist of covalently bonded segments of polyphenols, including anthocyanins, flavan-3-ols, and pyranoanthocyanins and are responsible for red wine’s color, astringency, and antioxidant activity. , The complex interactions between HPPCs and aroma compounds depend on various factors, including the type and structure of the aroma compounds and polymers and the composition of the wine matrix. These factors determine the physicochemical properties such as polarity, solubility, volatility, and molecular size. − Moreover, environmental conditions such as temperature, relative humidity, pH, and oxygen availability also play a role .…”