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56 WINES&VINES September 2016 WINEMAKING PRACTICAL WINERY & VINEYARD The must was inoculated seven hours after destemming with 250 mg/L of selected dry yeast (Lalvin EC-1118). Malolactic bacteria (Lalvin VP41 from Lallemand) was added 48 hours after yeast inoculation (10 mg/L). Diammonium phosphate was added to increase the yeast as- similable nitrogen to 225 mg/L before fermenta- tion. Sugar consumption during fermentation was monitored daily, and the tank temperature was maintained at 26° ± 2° C (75.2°-82.4° F). Cap management consisted of a whole- volume tank pumpover followed by a five- minute punchdown twice per day during active fermentation. Alcoholic fermentation was completed (reducing sugar less than 2 g/L) after nine to 10 days in all wines. Fermentation kinetics and temperature curves showed good reproducibility for all treatments during both years (data not shown). During post-fermen- tation, extended maceration (EM) wines re- ceived one 1-minute punchdown per day, after which the tanks were sealed and sparged under lid with N 2 . Visual seed maturity was determined fol- lowing a published protocol (see "Comparing Seed Maturity and Tannins"). 18 Under this protocol, seeds from a representative sample are contrasted against a color chart comprised of 12 colors with corresponding numbers, starting with a bright green (1), through green- yellow, yellow, yellow-brown and dark brown (12) as seeds ripen. 18 Fruit and wine analysis included anthocya- nins, total phenolics, protein precipitable tan- nins and wine color (CIELab). Pomace samples were analyzed for tannins recovered in the skins and seeds after the maceration length allotted for each treatment. The proportion of skin- or seed-derived tannins extracted into wine was calculated as the difference between what was found in either the skins or the seeds at harvest, plus the amount remaining in the pomace, and then dividing by the estimated amount of tannin extracted. 14 A trained panel provided descriptive senso- rial analysis (DA) of the wines, which occurred after three months of bottle aging (about 240 days after crushing). Briefly, DA was performed on the 2011 wines for aroma, color, taste and mouthfeel attributes (n = 3), as described in Lawless and Heymann. 14 Eleven panelists (five males and six fe- males; aged 22 to 74 years, average age 44.1, median age 34; six with previous DA experi- ence) were recruited from students, faculty, staff and retirees from the University of Cali- fornia, Davis, campus. Panelists participated in six one-hour training sessions in two weeks, followed by nine 30-minute evaluation ses- sions in two weeks. The wines were evaluated for color, aroma, taste and mouthfeel attributes in individual tast- ing booths under white light and in pear-shaped black ISO glasses (ISO 1977) labeled with three- digit random numbers, except for color, in which transparent ISO glasses were used. Results The main findings of this research indicate the following: • Wines made from the late-harvest treat- ment had significantly higher pH and lower titratable acidity compared to wines from the early harvest fruit (data not shown). The final EtOH concentrations confirmed that both the maturity and the EtOH adjustment treatments had the de- sired effect, yielding an overall difference of 2.7% (v/v) in the EtOH concentration between wines made from fruit with un- adjusted Brix and wines produced with chaptalization and/or the saignée/water- back adjustment treatments. • Seed tannins (on a fresh weight basis) were higher in the early harvest fruit during both years (see "Comparing Seed Maturity and Tannins"), but this higher concentration did not necessarily result in higher extraction into wine. Relative extraction of grape tannins was higher in riper fruit than in unripe fruit. • Overall extraction of fruit tannins (seeds and skins) into wine ranged from 12% to 16% and varied as a function of the growing season. Relative and absolute tannin extrac- tion was higher in 2012, which was warmer. • Extended maceration resulted in a decline in anthocyanins irrespective of fruit maturity and ethanol concentration, which, in turn, resulted in lower wine color saturation. • Tannin extraction into wine was not affected by the EtOH (11.72% to 14.40% v/v). No effect of the EtOH concentration on the proportion of seed-derived tannins was ob- served when comparing low EtOH wines with their high EtOH counterparts. Thus, differences in EtOH concentration during maceration as high as 2.7% (v/v) appeared to have no effect on the source of extraction of wine tannins (seeds or skins) or on the overall concentration of extracted tannins. • Extended maceration resulted in higher tan- nin extraction into wine. However, tannin extraction was independent of fruit maturity and EtOH concentration during maceration. • Of the total wine tannin content, extended maceration had about 80% of seed-derived tannins compared to control wines that had about 67% of seed-derived tannins. EXPERIMENTAL DESIGN FOR PRODUCTION OF MERLOT WINES 3 tank replicates Control (10 days of skin contact) Extended maceration (30 days of skin contact) Control Chaptalized to 25º Brix Early harvest (20.35º ± 0.16º Brix) 3 tank replicates 3 tank replicates Control (10 days of skin contact) Extended maceration (30 days of skin contact) 3 tank replicates 3 tank replicates Control (10 days of skin contact) Extended maceration (30 days of skin contact) Control Saignée and water-back to 20º Brix Late harvest (24.91º ± 0.46º Brix) 3 tank replicates 3 tank replicates Control (10 days of skin contact) Extended maceration (30 days of skin contact) 3 tank replicates Harvest date Sept. 22, 2011 Sept. 13, 2012 Harvest date Oct. 25, 2011 Oct. 17, 2012 Experimental design followed for making Merlot wines during the 2011 and 2012 harvests.