The Influence of Hydrolytic Enzymes on Tannin Adsorption-Desorption onto Grape Cell Walls in a Wine-Like Matrix

Abstract

This study evaluates the capacity of four hydrolytic enzymes to limit the interactions between grape cell-walls and tannins and/or to favor tannin desorption. Adsorption and desorption tests were conducted by mixing a commercial seed tannin with purified skin cell-walls from Syrah grapes, in the presence or absence of hydrolytic enzymes, in a model-wine solution. The effects of the enzymes were evaluated by measuring the tannins in solution by High Performance Liquid Chromatography (HPLC) and the changes in the cell wall polysaccharide network by Comprehensive Microarray Polymer Profiling (COMPP) while the polysaccharides liberated from cell walls were analyzed by Size Exclusion Chromatography (SEC). The results showed that the enzymes limited the interaction between tannins and cell walls, especially cellulase, pectinase and xylanase, an effect associated with the cell wall structural modifications caused by the enzymes, which reduced their capacity to bind tannins. With regards to the tannin desorption process, enzymes did not play a significant role in liberating bound tannins. Those enzymes that showed the highest effect in limiting the adsorption of tannins and in disorganizing the cell wall structure, cellulase and pectinase, did not lead to a desorption of bound tannins, although they still showed a capacity of affecting cell wall structure. The results indicate that enzymes are not able to access those polysaccharides where tannins are bound, thus, they are not a useful tool for desorbing tannins from cell walls. The practical importance implications of these findings are discussed in the manuscript.

Grape Pulp Fiber as Possible Fining Agents for Red Wine

“…Currently, numerous studies have reported the existence of interactions between wine phenolic compounds, such as anthocyanins and tannins, with plant cell walls from different sources such as apple [ 7 ], carrot [ 8 ], or the skin and pulp of the grapes [ 9 , 10 , 11 , 12 ].…”

The Application of Ultrasound and Enzymes Could Be Promising Tools for Recovering Polyphenols during the Aging on Lees Process in Red Winemaking

“…Our results showed that both the use of PEC and GLUC significantly increased the liberation of tannins compared to the control solution, and, as reported with total anthocyanins, the combination PEC + GLUC extracted the highest concentration of tannins. It is a well-known fact that both the plant cell walls and the yeast cell walls, which are in high concentrations in wine lees, have a great capacity to absorb tannins, absorbing even more than 50% of the tannins put in contact with them in model solutions [ 25 , 26 , 48 ]. Therefore, the greater effect of the combination of both enzymatic treatments, which act on both types of cell walls, was an expected result.…”

“…Mazauric and Salmon [ 48 ] determined that there was no preferential adsorption of low or high polymeric size tannins, since they barely detected variation in the mDP of the tannins that remained in the wine after putting them in contact with yeast lees for a week. However, it has been reported that the plant cell walls do preferentially bind tannins with a higher degree of polymerization [ 25 , 26 ]. Therefore, techniques that degrade these plant cell walls will release those higher molecular weight tannins, such as observed when US and the pectolytic enzyme (PEC) were used.…”

“…When only enzyme treatments were used, the pectolytic enzyme released the highest amount of polysaccharides. The capacity of this enzymatic preparation (composed of pectin lyase and polygalacturonase) to degrade plant cell walls and release soluble polysaccharides has been extensively studied in other studies [ 25 , 26 , 50 ]. In the study of Osete-Alcaraz et al [ 25 ], cell walls from Monastrell grape skin were put in contact with different hydrolytic enzymes and it could be observed how the pectin-lyase extracted a very high quantity of soluble polysaccharides (especially low molecular weight polysaccharides) from the purified grape skin cell walls.…”

“…On the other hand, and since plant cell walls also are present in the lees, the possible role of pectinase enzymes, whose main enzyme activities are methylesterase, polygalacturonase and pectin-lyase, on the desorption of phenolic compounds needs to be addressed. These enzymes facilitate the degradation of the pectin fraction of the grape cell wall that is part of the lees [ 24 ], and this degradation may release low molecular weight polysaccharides to the wine and help the liberation of polyphenols [ 25 , 26 ].…”