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November 2015 WINES&VINES 107 WINEMAKING skins and seeds were quite similar in astringency, though with a much higher average DP in skins than seeds, but a high DG of tan- nins in seeds. Average levels of polymerization and galloylation depend on grape variety, and the former is much affected by the state of ripening of the raw mate- rial. A 2013 work by German re- searchers with reference to the subquality of astringency (velvety, puckering, drying) concludes that average DP and DG are less important than they are with as- tringency intended as a single descriptor. These latest results confirm that there is still a lot to learn about relations between polyphenols and sensory effects. However, it should be remem- bered that polyphenols are particu- larly reactive, and they establish fairly complex reactions starting during the first stages of fermen- tation that alter molecular struc- ture and also sensory properties: For example, the formation of anthocyan-tannin polymeric pig- ments influences color but also reduces the sensation of astrin- gency in the wine. Preserving color Color, as we have mentioned, is a fundamental characteristic of red wines, and it's the one the taster perceives immediately, often in- fluencing his whole assessment. The technological problem, then, is working to maximize the coloring component during the extraction stage, but this is not enough because it is necessary to favor the chemical transforma- tions that induce a stabilization of the coloring component, which otherwise is easily subject to deg- radation or precipitation phe- nomena. For example, we can remember the influence that a yeast strain carries out on the phe- nolic profile of red wines due to the adsorption of anthocyanins on the wall of dead cells. The choice of a suitable selected strain could help reduce the phenomenon. Huge research work and applica- tion on a production level have made a lot of operational inter- vention available to winemaking companies, but that is another story. Enzo Cagnasso is a member of the Group on Wine Research at the Univer- sity of Turin Department of Agricultural, Forestry and Food Sciences. The school is located in Alba, Italy, an important winegrowing zone of southern Piedmont. The main work of the enological group is focused on indigenous grapevine va- rieties including Nebbiolo, Barbera, Moscato Bianco and others. GIVE US A CALL, OR JUST STOP BY You will always be able to speak to a knowledgeable and friendly person who can help. 7AM-5PM, Mon.-Fri. 7AM-noon, Sat. P.O. Box 540, Route 116 8 Ashfi eld Road, Conway, MA 01341 The electronically controlled FELCOtronic 820-HP offers incomparable power and precision. See our website or catalog, or stop by our showroom to see our wide range of hand tools and grape pruning and harvesting equipment. YEARS s i nce 195 4 800-634-5557 www.oescoinc.com scan this code to visit our website OESCO, Inc: Equipment, Supplies & Service All Year Long Prune & Harvest with Ease High temperatures are known to create conditions that increase the intensity of red wine color. • Reach 1/4" deep into wood surface, where Ozone & water-based chemicals cannot! • Proven to completely remove Brett & Zygo • Sanitize a barrel with less than ½ gal of H 2 O • Rejuvenate & preserve barrel toasting • Sanitize fermenters, storage tanks & bottling lines