Comparison of consecutive harvests versus blending treatments to produce lower alcohol wines from Cabernet Sauvignon grapes: Impact on polysaccharide and tannin content and composition

Comparison of water addition and early‐harvest strategies to decrease alcohol concentration inVitis viniferacv. Shiraz wine: impact on wine phenolics, tannin composition and colour properties

“…Although H‐2 had a similar monomeric anthocyanin concentration at the end of MLF, tannin was 2.3 times higher, and non‐bleachable pigment was 1.9 times higher in H‐3 relative to H‐2. These results strongly suggest that the increase in both extractable tannin and anthocyanin with the delay in harvest facilitated the rapid development of non‐bleachable pigment, which is in agreement with our previous observations (Bindon et al , , Schelezki et al ). A further consideration was on the visual properties of the wines made at the different harvest timepoints, which relates to the hue measure described by Somers and Evans () as the ratio of brown to red pigments.…”

“…Therefore, to find a strong relationship for three samples taken from a single vineyard lends support to the use of the uncorrected tannin extractability assay to monitor potential tannin extraction in wine during grape ripening, particularly for cultivars such as Shiraz where shrivel occurs late in the season (McCarthy and Coombe ). These results are supported by recent observations for Cabernet Sauvignon grapes by Schelezki et al (), who observed that loss of berry volume progressed during ripening, resulting in a significant increase in wine tannin concentration in the corresponding wines, which was well predicted ( R 2 = 0.94) by the uncorrected extractable tannin measure in the grapes.…”

“…The proportion of epigallocatechin extension units decreased when the tannin composition of H‐1 and H‐2 wines was compared with that of the H‐3 wines, a similar trend to that observed for tannin size and mDP in these treatments. The observed effect of grape maturity on wine tannin concentration and composition was not unexpected, having been observed in other studies (Bindon et al , Schelezki et al ), however, it is noteworthy that an increase in wine tannin through a delay in the grape harvest date is not always observed (Casassa et al ). The observed increase in wine tannin concentration with delayed harvest may have been because of an increase in tannin extractability in response to changes in grape subcellular structure (Bindon et al , ).…”

“…This study compared two strategies for alcohol reduction in red winemaking, early‐harvest and water addition to must, using phenolic outcomes in the wine as a potential indicator of quality loss or gain. Previous studies using a juice substitution approach to dilute Cabernet Sauvignon and Merlot, in which no change in the grape solids (seeds, pulp and skin) to must volume ratio occurred during fermentation, showed that alcohol could be effectively reduced by water addition with no adverse effect on wine phenolics (Casassa et al , Schelezki et al ,b). Given that Shiraz is a key red grape cultivar produced in Australia, it was of relevance to observe whether a similar outcome could be achieved.…”

“…Several unknowns exist for the water addition process following changes in Australian regulations (Food Standards Australia New Zealand ) which allow water to be added to must. Studies have been conducted for Vitis vinifera cultivars Cabernet Sauvignon and Merlot, whereby must was runoff after crushing and an equivalent volume of water added (juice substitution) to decrease the alcohol concentration of finished wines, with no significant change to wine tannin concentration or colour (Casassa et al , Schelezki et al ,b). These results indicated potential benefits of water addition to reduce alcohol but needed to be confirmed for Shiraz, the principal grape cultivar grown in Australia.…”