Issue link: http://winesandvines.uberflip.com/i/383377
64 p r a c t i c a l w i n e r y & v i n e ya r d O c t O B e r 2 0 1 4 w i n e M A K i n G wines with LT oak staves, a 30% loss for wines with Noisette, a 50% – 60% reduc- tion for wines with MT, MT+ oak staves and the largest decrease of about 70% for wine with Special staves. In the first months of a Merlot trial in Medoc, France, ellagitannins were extracted at a rate faster than the rate of the condensation reactions between ella- gitannins and other nucleophilic wine constituents (catechin, epicatechin and ethanol). When most of the ellagitannins have been extracted from the first mil- limeter of the wood, the red wine goes deeper into the wood to extract more ella- gitannins (consequently, at a slower rate). Not only do the toasting stages diminish the quantity of these com- pounds but also the watering procedure. Wine with light toast staves extracts not only more ellagitannins but also faster than other samples. The above decreases during the maceration time can be attrib- uted to the high reactivity of ellagitan- nins toward other wine constituents. 8,10 Oak wood sensory evaluation Figure 3 shows the average intensity of each gustatory and olfactory attribute during the different contact times of the control wine and the same wine treated with oak wood for 12 months. The wines treated with toasted oak staves become less astringent and bitter during the contact time. This reduction in the astrin- gency sensation could be attributed to their lower ellagitannins levels and the chemical complex formation between wine tannins, polysaccharides and pep- tides brought out by the oak. For all wines treated with toasted oak staves, it is observed that vanilla, spicy and woody characters increase along with sweetness. The woody aroma of wines aged with staves toasted in the "Special" method was more intense after two months of contact, afterward it did not intensify significantly. Therefore, judges found that woody, spicy and vanilla aro- mas do not fluctuate during the macera- tion time for wines treated with Special toasted staves. The watering process dur- ing the toasting process influences not only the level of hydrosoluble tannins but also a wine's sensory profile. Correlations between sensory and chemical results The analysis of variance revealed that the toasting method has a significant impact (p less than 0.05) on chemical composition and sensory perception of oak wood extract. Each sensory descrip- tor was correlated with the chemical con- centration of the oak wood compounds of interest (Table I). This procedure allowed us to measure the extent to which sensory and chemi- cal variables are correlated. Based on the correlation analysis, astringency and bit- terness intensify significantly with ella- gitannins concentration (R = 0.828 and p = 0.001 for astringency, while R = 0.607 and p = 0.003 for bitterness). The highest astringency and bitter- ness was perceived for wines with LT oak staves (4.98 for astringency and 4.67 for bitterness) containing 27.33 mg/L of released ellagic acid. The above estab- lished correlations permit characteriza- tion of tannin quality when ellagitannin levels are known. Additionally, astrin- gency and bitterness were more per- Figure 2. Evolution of total ellagitannins during different contact times.