Characterization of Georgian white grape wines made ... - Oiv2010.ge

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stem contact and all wines – without. Rkatsiteli from Kardenakhi fermented and aged with stem contact, had less purity and less brightness than wines vinified without stems. Names Table 1 General composition of amphorae wines alcohol (% v/v) tot. acidity (gL -1 tartaric acid) volatile acidity (gL -1 acetic acid) pH purity brightness Dom. wave length Kakhuri Mtsvane 12,7 5,1 0,48 3,47 16,02 91,22 575,85 Rkatsiteli Kardenakhi 11,9 5,2 0,44 3,49 12,29 92,86 576,07 Rkatsiteli Gurjaani 12,6 5,7 0,41 3,22 13,15 92,43 576,22 Rkatsiteli Kardenakhi with stems 11,8 5,0 0,54 3,45 6,67 85,75 577,19 The amounts of volatile compounds determined by gas-chromatography in Rkatsiteli and Mtsvane grape wines are presented in Tab. 2. The reported metabolites, even if they were expression of a particular vinification process, did not let a punctual analysis about their origin because of the unknown development of microflora during fermentation. Higher alcohols and esters, produced during alcoholic fermentation, play an important role in the flavour of the wines, depending on the types of compounds and their concentrations (Valero et al. 2002). The most plentiful compounds were the higher alcohols, in agreement with the literature (Baumes et al. 1986). At concentrations below 300 mgL -1 they certainly contribute to the desirable complexity of wine; when their concentrations exceed 400 mgL -1 , higher alcohols are regarded as a negative quality factor (Mateo et al. 2001). The total concentration of higher alcohols in experimental wines was below 300 mgL -1 . It can be mentioned, that there was not any difference among wines, except of isoamyl alcohol content, which was higher in stem contact wine. Also this last wine characterized with highest amount of 1-hexanol, which indicated that extended the pomace and especially the stem contact time can raise the formation of this compound, which agrees with results obtained by other authors (Cordonnier and Bayonove 1979, Rankine and Pocock 1969). It is significant, that there was notable difference between stem and non-stem contact wines in the content of ethyl lactate, ethyl 3-OH-butyrate, ethyl 4-OH-butyrate and monoethylsuccinate, which were much higher in first one. Wine made by Kakhuri Mtsvane grape variety was distinguished with higher concentration of 2-phenyl ethanol, 2-phenyl ethyl acetate. 4
Compounds Table 2 Volatile Compounds in amphorae wines (µgL -1 ) Kakhuri Mtsvane Rkatsiteli Kardenakhi Rkatsiteli Gurjaani Rkatsiteli Kardenakhi with stems isoamyl acetate 265 241 119 144 hexyl acetate 88 64 64 68 2-phenyl ethyl acetate 83 n.d. 12 11 Σ acetates 436 305 195 223 acetic acid (gL -1 ) 0.48 0.44 0.41 0.54 Σ acetates/ acetic acid (gL -1 )x10 -3 0.91 0.69 0.47 0.41 ethyl hexanoate 334 235 390 232 ethyl octanoate 294 207 278 198 ethyl decanoate 37 n.d. 39 25 Σ ethyl esters 665 442 707 455 hexanoic acid 2385 1662 2708 1872 octanoic acid 2741 1917 2629 1724 decanoic acid 744 363 419 311 Σ fatty acids 5870 3942 5756 3907 Σ ethyl esters./ Σ fatty acids 0.113 0.112 0.123 0.116 n-pentanol 18 18 20 35 ethyl lactate 26 n.d. 38 263 n-hexanol ethyl 3-OH-butyrate 1236 17 853 41 992 43 1787 71 isoamyl alcohol 62226 63550 66785 101450 diethylsuccinate 2294 1770 3142 1832 ethyl 4-OH-butyrate 281 255 221 480 N(3-methybutylacetamide) 5 n.d. 13 9 benzyl alcohol 46 12 24 20 2-phenyl ethanol 37715 24792 24245 23102 Monoethylsuccinate 1580 560 2629 3782 Tab. 3 presents the results from HPLC and spectrophotometer analyses. There was not fixed any important difference among non stem contact wines. But it can be noted, that stem contact wine had less contents, in all parameters, to the contrary of wine made by the same variety, without stems. The possible explanation of this can be - extending the maceration time and especially stem contact, might extract more of other compounds, which would absorb or interact with various polyphenols and thus reduce their levels in wine (Spranger et al. 2004). Table 3 Polyphenolic compounds in amphorae wines (mgL -1 ) caftaric acid cis-pcoumta ric acid trans-p coumta ric acid procya ni-dine B1 (+)- catechi n (-)-epicatechi n flavans total polyphenols total flavo noid s Kakhuri Mtsvane 20,8 2,1 4,7 30,0 36,7 10,0 1380 1670 1680 Rkatsiteli Kardenakhi 23,0 3,0 7,6 33,2 30,1 8,0 1530 1600 1710 Rkatsiteli Gurjaani 20,7 2,9 7,4 27,2 21,9 4,5 1320 1760 1760 Rkatsiteli Kardenakhi with stems 15,9 2,8 5,9 25,7 25,0 7,1 1200 1490 1360 The results obtained in the analyses of the volatile compounds released by aroma precursors after enzymatic hydrolysis are shown in the Tab. 4. Values of some terpenol compounds, such as linalool, α-terpineol, cis-furanlinalool oxide, of Kakhuri Mtsvane grape wine are more higher in comparison with three different Rkatsiteli wines. Differences among wines from the same varieties and between wines from different varieties are better explained when we look to the ratio among specific compounds rather than to each compound by itself. So, the relations among linalool/nerol and linalool+nerol+geraniol/α-terpineol are different in 5
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