Interactions between grape skin cell wall material and commercial enological tannins. Practical implications

Area of Science:

• Enology
• Food Chemistry
• Plant Biochemistry

Background:

• Proanthocyanidins are key phenolic compounds in wine impacting color and mouthfeel.
• Enological tannins are widely used in winemaking to modulate wine structure and stability.
• Grape cell wall components can interact with wine constituents, potentially affecting tannin levels.

Purpose of the Study:

• To investigate the adsorption of commercial enological tannins by grape skin cell wall material.
• To determine the factors influencing the interaction between proanthocyanidins and cell walls.
• To assess the enological implications of these tannin-cell wall interactions.

Main Methods:

• Preparation of insoluble cell wall material from Vitis vinifera cv. Monastrell grape skins.
• Incubation of cell wall material with six different commercial enological tannins.
• Analysis of non-adsorbed proanthocyanidins using phloroglucinolysis and size exclusion chromatography.

Main Results:

• Cell wall material demonstrated a significant affinity for proanthocyanidins, with up to 61% binding observed for one tannin.
• Adsorption was primarily related to the molecular mass of the proanthocyanidins, rather than their galloylation percentage.
• Size exclusion chromatography revealed changes in the molecular mass distribution of tannins after interaction with cell walls.

Conclusions:

• Grape skin cell wall material effectively adsorbs enological proanthocyanidins.
• The molecular mass of proanthocyanidins is a key factor in their adsorption by cell walls.
• Understanding these interactions is crucial for optimizing the timing of enological tannin addition during winemaking.