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

The hard part of grape cluster influence on the quality of kakhetian wine
type
M. Mikiashvili 1 , Z. Kiknavelidze 2 , M. Khositashvili 3 , B.Nakhucrishvili 3 , S. Favale 4 , G.
Ciolfi 4
(1) Organization: testing laboratory L.T.D. ― Norma‖ (1) , L.T.D. ―Vazi +‖ (2) , Institute of
Horticulture,Viticulture and Wine-making, (3) , CRA-Unita di Ricerca per le Produzioni
Enologiche dell’ Italia Centrale. (4) .
Address: 1- V. Ninua,3, Tbilisi, Georgia, marika.mik@gmail.com
2- Tsinamdzgvrishvili,4, Zahes, Tbilisi, Georgia, zura_kiknavelidze@yahoo.com
3- M.Gelovani, 6, Tbilisi, Georgia, marina_khositashvili@yahoo.com
4-Velletri, Via Cantina Sperimentale, 1 – 00049 Velletri (RM), Italy stefanofavale@libero.it
Abstract
The ancient Georgian traditional wine-making method stipulates the processing of grapes
and alcoholic fermentation of must with stem contact in Kvevri (earthwork amphorae) buried
into the ground. The received wine material ages in Kvevri during three - five months with
hard parts of grape. The aim of our work was to study stem affect on the quality of kakhetian
wine. We studied phenolic and aromatic compounds of samlpes by HPLC and Gas mass
spectrometry. The wine made by Kakhetian technology contained high amounts of phenolic
rather than wine made by European one. Long wine material maceration prolong the phenolic
compound extraction from hard parts of seed and especially from stem. In wines made in
earthwork amphorae were found the following correlation: samples with stem contact
consisted less quantity of phenolic carbo acids, total polyphenols (1600 - 1490 mgL -1 ) and
total flavonoids (1710- 1360 mgL -1 ). The reduction of phenolic compound by stem contact in
wine materials may be caused by correlation of phenolic compound extracted from stem (by
coagulation and sedimentation) or by their adsorption by stem.
La technologie de la fabrication du vin géorgien traditionnel prévoit le traitement du raisin
et la fermentation alcoolique du marc avec les rafles dans les Qvevri (les cruches, installées
dans la terre). La matière du vin obtenue subit la formation avec les parties solides de la
grappe pendant trois-cinq mois dans les Qvevri. L’objectif de l’examen consistait à examiner
l’influence de la rafle sur la qualité du vin kakhétien. Il a été examiné dans les spécimens les
composés phénoliques, composants aromatiques et par l’analyse à l’aide de spectromètre de
masse liquide et gazeuse. Dans les matières du vin fabriquées de technologie kakhétienne les
composés phénoliques étaient partout augmentés que dans les matières européennes. Avec la
temporisation durable de la matière du vin sur le marc il est prolongé l’extraction des
composés phénoliques depuis des pièces solides de la grappe, surtout depuis des rafles. Ces
modeles, lequels a arrêté avec la rafle il a raccourcit pour sentir les acides carbon de phenol,
les polyphenols general (1600 -1490 mgl -1 mde) et les flavavonoides (1710 - 1360 mgl -1 mde)
dans la matière du vin raccourcir les matieres phenols en contact avec la rafle, il est
provoquée de l’action réciproque des composés phénoliques provenus de la rafle (avec la
coagulation et la sédimentation) ou de l’adsorption par la rafle.
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Introduction
The main subject of various published works about wine compounds, is the study of
phenolic and volatile ones, because they are very important contributors for wine sensory
properties — colour, flavour, astringency, and bitterness (Arnold and Noble 1978,Arnold et
al.1980, Cocito et al. 1995, Kotseridis and Baumes 2000, Powers et al. 1988, Singleton 1992).
It is well known that for given grape varieties, the kind of winemaking technology can
notably affect the levels of phenolic and volatile compounds of wine. Wines made by skin
fermentation with stem-contact contained much more polymeric phenols than those made by
skin fermentation without stem-contact wine, and extending pomace contact time increased
both total and polymeric phenol levels in wines (Kantz and Singleton 1991). Stem contact
wines contained much higher concentration of proanthocyanidins than non-stem contact
wines (Bourzeix et al. 1986, Spranger et al. 2004, Sun et al. 2001), due to the important
transference of this compounds from stems to wines during fermentation (Sun et al.
1999).The aroma of white and red wines is the product of a biochemical and technological
succession and it is decisively influenced by the alcoholic fermentation procedure (Bayonove
et al. 1998, Rapp 1988). The complexity of wine aroma is defined by all technical factors. As
many viticulture and oenological factors greatly influence the types and concentrations of
flavour components (Zhou et al. 1996), the ability to define each individual component would
provide an approach to optimize the operational conditions, mainly the winemaking
technologies.
Viticulture and wine making in Georgia have been widely practiced since ancient time
(Olmo 1976, Zohary and Hopf 1993, Zohary and Spiegel-Roy 1975).Continuous and
intensive selection of grape varieties that favoured the production of desired wine styles led
over the centuries to a plenty of native cultivars, which possess various distinct oenological
characteristics and organoleptic properties. Good example of variety of Georgian winemaking
is local type Kakhetian wine, which is made in earthwork amphorae (Beridze 1965)
by using all parts of grape during fermentation and the first step of wine aging (Marjanishvili
1983, Nanitashvili 1978, Valero et al. 2002). Because of this, wine is characterized with
varietal aroma, high extract and polyphenolic consistence. For the production of this type of
white wine are always used the following grape varieties: Rkatsiteli (V. vinifera L.) and
Kakhuri Mtsvane (V. vinifera L.).
The object of our work was to study characteristic consistence of Kakhetian wine type
made in earthwork amphorae using different grape varieties from diverse areas and prepared
in different way.
Materials and methods
Standards
Used materials: (+)-catechin, (-)-epicatechin, hexyl acetate, ethyl hexanoate, ethyl
decanoate, ethyl lactate, ethyl octanoate, (Sigma, USA), procyanidin B1 (Extrasynthèse,
France), caffeic acid , geraniol, nerol, linalool, benzyl alcohol, ethyl 3-OH-butyrate (Fluka,
Switzerland), α-terpineol, gallic acid, 2-phenyl ethanol, isoamyl acetate, hexanoic, octanoic
and decanoic acids (Merck-Schuchardt, Germany), 2-phenyl ethyl acetate, diethylsuccinate
(Carlo Erba, Italy).
Winemaking technologies
Grapes were harvested in September 2007 at a technological maturation. All parts of
grapes were processed in earthwork amphorae: Kakhuri Mtsvane from Akhmeta region,
Rkatsiteli from Kardenakhi region and the same variety from Gurjaani region – all without
stem contact and also Rkatsiteli from Kardenakhi region with stem contact. Fermentation
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proceeded 10-12 days, with stirring every 6 hours and approximate temperature – 20°C,
thanks to spontaneously cooling (which takes place by good thermoconductivity of earthwork
amphorae in the ground); at the end of fermentation and filling-up, SO 2 (30 mgL -1 ) was
added; wines were left in earthwork amphorae until March of next year, then transferred to
stainless steel tanks and stored at room temperature before analyses.
Chemical and physical parameters of wines
Alcohol content, pH, total acidity, volatile acidity and chromatic characteristic were made
according to the official methods of O.I.V. (1990).
Spectrophotometric analysis
Total polyphenols, flavans and flavonoids were determined according to Di Stefano et. al.
(1989).
HPLC analyses
Catechins and hydroxycinnamic acids were performed according to Ummarino et al.
(2001). Instrument was as follows: degasser, quaternary pump, thermostated column
compartment (Agilent Technologies, 1100 series, USa), autosampler, DAD detector (Agilent
Technologies, 1200 series, USA); guard column ODS-Hypersil (C18) 20 x 2.1 mm-5µm (CPS
Analitica, Italy); column ODS Hypersil 200 x 2.1 mm – 5µm (CPS Analitica, Italy) for
catechins and hydroxycinnamic acid. Quantities were expressed as mgL -1 for wine;
particularly, hydroxycinnamic acids were expressed as mgL -1 of caffeic acid.
Volatile compounds
Volatile compounds were determined by gas chromatography as described in literature
(Gianotti and Di Stefano 1991). Chromatographic conditions were: instrument GC 8000
(Fisons Instruments, Italy), detector FID, helium flow 2.9 mLmin -1 , column HP- FFAP 50 m
x 0.32 mm x 0.50 µm (Agilent Technologies, USA), injection temperature 220 °C, oven
temperature 33 °C held for 5 min, then 3 °C min -1 to 200 °C, then isotherm for 10 min, then
10 °C min -1 till 220°C and isotherm 220°C for 15 min. Detector temperature was 245 °C, and
injection volume - 3 µL. Commercial standards were used in order to identify and quantify
volatile compounds in sample, added with 1-heptanol as internal standard.
Varietal compounds
Glycosidically bound varietal compounds from wines were determined according to Di
Stefano (1996). For enzymatic hydrolysis, overnight at 40°C, Cytolase (Genecor) was used.
The analyses were carried out by GC HP 5890 Serie II and MS HP 5972, column HP-
Innowax 30 m x 0.25 mm x 0.25 µm, splitless injection 2 µL, helium flow 1 mLmin -1 ; starting
temperature 30°C for 2 min, oven temperature 30°C min -1 from 30°C to 60°C, 2°C min -1 up to
160°C, 3°C min -1 up to 230°C, and then held for 10 min. Commercial compounds were used
for calibration, with internal standard method. 200 µL of 1-heptanol (67,6 mgL -1 in
methanol/H 2 O 20% v/v ) were added as internal standard. The concentration of each varietal
compound was expressed in µgL -1 , and in µg of linalool per litre of wine, when commercial
standard was not available.
Results
The general compositions of different wines are shown in Tab.1. From this table, it can be
seen, that between Rkatsiteli Kardenakhi samples fermented with and without stem contact,
there is not difference in all analysed factors, thus according to Ribereau-Gayon et al. (2000)
wines fermented without destemming must contain less volumes of alcohol and acidity. It can
be underlined a little difference in chromatic characterization, that comes among wines with
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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.
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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
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Kakhuri Mtsvane and both Rkatsiteli from Kardenakhi wines (with and without stem contact),
which, in turn, are different from another region Rkatsiteli (Kardenakhi) wine.
Compounds
Table 4 Varietal compounds in amphorae wines (µgL -1 )
Kakhuri
Mtsvane
Rkatsiteli
Kardenakhi
Rkatsiteli
Gurjaani
Rkatsiteli
Kardenakhi with
stems
trans-furan linalool oxide 9,3 6,1 7,8 6,5
cis-furan linalool oxide 19,9 11,9 13,8 11,3
linalool 25,8 12,6 4,3 12,1
α-terpineol 11,2 6,0 6,6 5,7
trans-pyran linalool oxide 9,8 4,1 6,7 4,7
nerol 6,9 15,8 14,3 19,3
geraniol 30,9 48,3 35,5 61,0
trans-8-OH-linalool 54,4 40,8 33,0 53,0
cis-8-OH-linalool 65,8 116,4 36,2 44,4
trans/cis furan linalool oxide 0,5 0,5 0,6 0,6
trans/cis pyran linalool oxide 0,9 0,7 0,8 0,9
trans/cis 8-OH-linalool 0,8 0,4 0,9 1,2
linalool/geraniol 0,8 0,3 0,1 0,2
nerol/geraniol 0,2 0,3 0,4 0,3
linalool/nerol 3,7 0,8 0,3 0,6
[linalool+nerol+geraniol]/ α –
terpineol
5,7 12,8 8,2 16,2
Conclusion
Wines in earthwork amphorae were vinified using ancient, traditional method of
winemaking, which can be fined as good quality wine in regards of all standards. Were
studied their polyphenolic and volatile composition. Main differences were notified among
wines made with and without stem contact. It was distinguished that stem contact wine
consists less quantities of various polyphenols and more – n-hexanol and isoamyl alcohol.
About varietal content can be said that by using this technology no difference was found
among wines.
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