Red Wine Tannin Structure-Activity Relationships during Fermentation and Maceration

Area of Science:

• Enology
• Food Chemistry
• Analytical Chemistry

Background:

• Tannins significantly influence red wine astringency and mouthfeel.
• Understanding tannin structure-activity relationships is crucial for wine quality control.

Purpose of the Study:

• To investigate the correlation between tannin structure and activity in commercial red wine fermentations.
• To determine the key factors driving tannin-wine interactions during extraction.

Main Methods:

• Tannins were isolated from wine samples using low-pressure chromatography.
• Tannin characterization involved gel permeation chromatography and phloroglucinolysis.
• Tannin activity was assessed by measuring hydrophobic interactions with a polystyrene divinylbenzene HPLC column.

Main Results:

• Tannin activity is primarily dictated by molecular size.
• Seed tannins positively correlated with activity, while skin and pigmented tannins showed negative associations.
• Tannin oxidation was found to reduce activity, and increased molecular mass, not oxidation, correlated with perceived astringency.

Conclusions:

• Molecular size is the dominant factor in tannin activity during red wine extraction.
• Seed tannin content is beneficial for activity, whereas skin and pigmented tannins may be detrimental.
• Controlling tannin oxidation and focusing on molecular mass are key for optimizing astringency quality.