Influence of Polysaccharides on Extraction of Polyphenols during Maceration at Different Grape Maturities
Jan-Peter Hensen,* Fiona Hoening, and Fabian
Weber
*Rheinische Friedrich-Wilhelms-Universität Bonn,
Friedrich-Hirzebruch-Allee 7, Bonn/ North Rhine-Westphalia/53115,
Germany (hensen@uni-bonn.de)
Red wine sensory properties and quality largely depend on
extraction of anthocyanins and tannins during winemaking and
their interactions with other wine components. The climatic
conditions in cool climate regions make it much more challenging
to produce red wines with deep color and a full body, presumably
because of the poor extractability of phenolic compounds. The
high demand for those types of red wines necessitates the full
use of the grape’s phenolic potential. There is, however, still a
lack of knowledge regarding the mechanisms that change the
extractability and the impact of polysaccharides. To further
understand the correlation between grape maturity and polyphenol
extractability, the influence of grape polysaccharides
was analyzed in microvinifications of Cabernet Sauvignon and
Pinot noir in 2020. Grape polysaccharides extracted from
differently ripe grapes were added to musts from three harvest
dates (Cabernet Sauvignon: 17.1, 20.9, 21.8 Brix; Pinot noir:
16.7, 19.7, 21.6 Brix). The added polysaccharides were previously
extracted as the alcohol-in- soluble residues at three different
harvest points in 2019 from the respective berries from the same
vineyard. The addition of these polysaccharides during maceration
influenced tannin concentration in the resulting wine, while
anthocyanin concentration was determined by actual berry
ripeness. The observed effects were greater when polysaccharides
from riper berries were added. Possible interactions with the
polysaccharides stabilized or bound tannins in the must, which
led to contrasting results in the different wines. While Pinot
noir wines had more measurable tannin concentrations, addition of
polysaccharides led to a decreased tannin concentration in
Cabernet Sauvignon wines. The stabilizing effects could be based
on protective reactions, with other wine components hindering
those to bind tannins. The smallest impact of added
polysaccharides was found in must from unripe grapes. Varietal
and ripeness-specific effects highlight the diverse interactions
of polysaccharides with polyphenols during vinification.
Funding Support: The German Ministry of Economics and Technology (via AiF) and the FEI (Forschungskreis der Ernährungsindustrie e.V., Bonn). Project AiF 20024N.