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13CHEMICAL SCIENCES
HEAVY METALS IN GEORGIAN RED WINES KINDZMARAULI AND SAPERAVI OF WINE ENTERPRISE
"KHAREBA"
Kekelidze N.
Ivane Javakhishvili Tbilisi State University
Tbilisi, Georgia Kekelidze T.
Ivane Javakhishvili Tbilisi State University
Tbilisi, Georgia Akhalbedashvili L. Ivane Javakhishvili Tbilisi State University
Tbilisi, Georgia Mirtskhulava M. Ivane Javakhishvili Tbilisi State University
Tbilisi, Georgia
Maisuradze G.
Ivane Javakhishvili Tbilisi State University
Tbilisi, Georgia
Kvirkvelia B.
Ivane Javakhishvili Tbilisi State University
Tbilisi, Georgia Tsotadze G.
Ivane Javakhishvili Tbilisi State University
Tbilisi, Georgia
Mskhiladze A.
Ivane Javakhishvili Tbilisi State University
Tbilisi, Georgia Lipartiani V. Wine enterprise "Khareba "
ABSTRACT
At valuation security of wines special role should be given to analytical control of pollutants, such as heavy metals (HM). Content of HM in wines depends on type of soil, processing conditions of vineyard, climatic conditions, vinification, anthropogenic factors and so on.
In work first studied the migration of heavy metals Pb, Cu, Zn, Cd, Co, Ni, Mn, Fe in a chain: soil^-stem^-skin^pulp^-wines Kindzmarauli and Saperavi from unique vineyards Mukuzani and Sabue of Kakheti region of Georgia.
To determine the HM content in samples atomic absorption spectrometry was used. The quantity of HM in chain soil ^-stem^-skin^pulp twines decreased more than an order, but non-uniquely. In leaves content of Cu and Fe in 5-10 times prevails their content in soil and skin, in juice and wine decreased in hundred times. The content of all HM in Georgian wines studied not prevails 0.2 mg/l. Most of HM in the grapes precipitates during fermentation into sediments, which is the reason for their significantly lower content in wine. Keywords: Georgian red wines, heavy metals, chemical analysis
Introduction
Wine is much more complex and heterogeneous liquid than any other beverage [1, 2]. Growing grapes, especially crops of red grapevine, is demanding to harvest. Due to numerous amounts of compounds, which are e.g. water, ethanol, minerals, inorganic compounds, organic acids, carbohydrates, and polyphenol compounds [3], the quality of wine is important. Among a lot of inorganic compounds heavy metals play the significant role as essential trace elements necessary for
good health, but they could be toxic when their concentrations exceed limits of safe exposure [4-8]. The amounts of heavy metal in wine vary depending on the specific cultivar, the grapevine-growing soil, the climatic conditions, the methods of pest and disease control, the grape processing method and vinification [8, 9, 10].
More than 500 grades of grapes from 4.5 thousand of grades known to the world, growing in the territory of the Georgia indicate that this country is one of the ancient world centers of formation of cultural and wild
grapes. Archaeologists have found evidence that eight thousand years ago in Georgia were producing the wines from a cultivated vine [11].
The wines of Kakheti (Eastern Georgia) are rightly considered one of the best first-class table wines, which successfully compete with the wines of the most famous French brands and often surpass them.
One of the most known grades of grapes is Sa-peravi - the red grade of grapes of the late period of maturation, which has received the name "dyer" thanks to abundance of dyes in berry. Wines, received from it, are of excellent quality, have very high potential of storage -50 years and more [12]. The highest quality of
wines from Saperavi is noted aged from 4 up to 30 years.
Among the other wine-making countries Georgia is famous for the unique Kakhetian manufacturing technique of wine, whose essence consists in storage and aging of wine in special clay jugs of a cone-shaped form - kvevri (with a capacity up to 500 decalitres). Kvevri is dug into the earth, leaving only the jug hole on the surface (fig.1). Such immersion allows achieving the constant temperature (14 degrees), ideal for fermentation and storage of a mash that stipulates the perfect quality of Georgian wine [13]. In 2013, the Georgian method of making wine in the kvevri was listed as an intangible cultural heritage of UNESCO.
<№ • J"
s^ti'M. f^^^
Fig.1. Georgian jug for maturation and saving wines - kvevri
It was the application of Kakheti winemaking technology that prompted us to conduct a comparative chemical analysis of red wines from Saperavi grapes growing in eastern Georgia and compare them with wines, made from the same sort, but according to European technology. Objects for research are kindly supplied by the wine enterprise "Hareba". The study includes a complete chemical analysis of the mineral constituent represented by both natural inorganic substances and compounds of anthropogenic origin.
Because of a valuation the security of wines special role should be given to analytical control of pollutants, such as heavy metals (HM) which potentially have toxic and carcinogenic properties. Moreover, in recent work first studied the migration of more widespread heavy metals Pb, Cu, Zn, Cd, Co, Ni, Mn, Cr and Fe in a chain:
soil^-stem^-skin^pulp^juice^-wmes Kindzmarauli and Saperavifrom unique vineyards of Kakheti region of Georgia.
Methods and objects of study
Soil samples were taken in 5 cm layers up to 50 cm in the Khakheti region -Mukuzani and Sabue vineyards. All solid samples were treated by method of dry mineralization according to ISO 19730:2008 and GOST 26929-94. The stem and grape samples were taken at the same site as the soil samples.
a) The soil samples were collected, dried, ground and passed through a 1 mm sieve. 10 g air-dry soil was weighed in a 250 ml conical flask and moistened by bidistilled water. Then 40 ml of a mixture of HNO3 and HCl (1:3) was carefully added to avoid any losses in the course of the reaction with the organic matter of soil. The sample was heated for 3 h on a sand bath. After cooling, it was transferred into a 100 ml flask and brought to volume with bidistilled water.
b) The grape analyses were conducted after the technological ripeness (in the end of October) with a must sugar content of 22 - 25 percent and titrable acids-7 - 8.5 g/dm3. Grape berries (about5 000 g per sample) were cut using grape shears with rubber gloves.
The grapes were divided in skin, pulp, juice,using stainless steel forceps and treated by the method of dry mineralization by following way:
A 10 g sample of skin (pulp or juice respectively) was weighed in a quarz crucible and put into a furnace (T = 400°C) until ashing has occurred. After cooling to a room temperature, 5 ml HNO3 (1:1) was added, evaporated in a sand bath and put again into the furnace (T = 400°C). The procedures were repeated until the ash was white. It was finally dissolved in 2 ml 20 % by v/v HCl, transferred in a graduated 50 ml flask and brought to volume with bidistilled water.
c) Wine samples were treated by the method of wet mineralization. A sample of 50 ml red wine was put into a glass, 5 ml con. HNO3 was added and heated on a sand bath. If the sample was not discoloration for 1 hour, it was cooled and then 2 ml con. HNO3 was added. Heating was continued till the solution discoloration, after which the latter was transferred into a graduated 10 ml cylinder and brought to volume.
d) The HM content in samples was measured, using flame atomic absorption spectrometry (spectrometer of firm Perkin-Elmer AAnalyst 200) in accordance with ISO 11466 and GOST P 53218-2008. An air-acetylene flame was utilized for all the elements.
e)The reagents used in the experimental studies had the qualification "analytical-grade", standard samples of the composition of solutions of metals of the GSO series and multi-element standard solutions ICP-MS-68A-A CP-MS-68A-B and ICP-MS-68A-C were used.
The distribution of the content of TM in the soil and in the solid parts of the vine (Figures 2, 4) is as follows: most of all is contained manganese, copper and iron in leaves, then in stems and skin. But already in the liquid part (Figures 3, 5) - this is juice, fermented wort and wine sealed - the content of these elements is reduced by two orders of magnitude. Consequently, when obtaining the juice, migration of TM from the stems and skin almost does not take place. But in the
The experiments were done in triplicate, and the results are shown as the mean values of three measurements.
Results and discussion
Analysis of heavy metals in uncontaminated soils of the vineyards of Sabue and Mukuzani showed that Sabue's soil is distinguished by a higher (almost twofold) content of copper, zinc and a small degree of iron and lead. Only the content of cadmium is twice higher in Mukuzani, than in Sabue soils. With increasing depth of soil from 5 to 50 sm HM contents decreased in Mukuzani vineyard ( table 1): Cu from 53.65 till 42.6mg/kg in and Zn from 78.5 to 67.1mg/kg, but in more clean region - Sabue vineyard, content of all elements studied increased a little with increasing of depth. It is necessary to note especially the anomalously high content of manganese in the Mukuzani soils and in particular of the Sabue soils, where the content of manganese is higher at depth. This fact points to the natural, and not anthropogenic, origin of Mn in the soils of Kakheti. But the level of any of the presented elements does not exceed the officially sanctioned OPC (Officially Permissible Concentration) for HM in neutral (loamy and clay) soils with pH> 5.5. Thus, the content of HM in the soils of vineyards of Sabue and Mukuzani is within the norm.
Table 1.
process of alcoholic fermentation, the main amount of copper, which enters the must and wine materials from the grapes, precipitates and is removed from the fermenter. Therefore, according the classical scheme of processing grapes, the content of copper in young wine materials is insignificant. Moreover, as an excellent oxidation catalyst, copper in small doses can accelerate the process of must fermentation, in particular, in the transformation of phenolic compounds.
300 i? 250 200 150
C
£ 100 J 50 0
iL
Cu Fe Co
Ni Cd Zn Mn Pb Cr Element
Soil-5 (M) Soil-50 (M) leaves stem I skin
The content of HM in soils of vineyard Mukuzani and Sabue, mg/kg
N Sample Cu Fe Co Ni Cd Zn Pb Mn Cr
1 Soil-5(M) 53.65 36.25 25.45 66.90 1.95 76.15 36.80 1200 59
2 Soil-50(M) 42.60 31.25 23.70 60.40 2.55 67.10 37.20 1280 57
3 Soil-5(S) 122.20 50.00 24.45 64.75 1.05 130.5 41.35 2560 67
4 Soil-50(S) 147.00 50.00 22.80 64.85 1.15 136.5 47.00 2640 63
Fig. 2. The migration of HM elements from soil to solid parts of vine of vineyard Mukuzani: content of Mn is
1200 and 1280 mg/kg
2,5
M 2 £ 2
" 1,5 juce
Wine (cisterna)
^5, ■ ■ I Wine (sealed)
A
Cu Fe Co Ni Cd Zn Mn Pb Cr Element
3
0
Fig. 3. The content of HM elements in juice and wine Kindzmarauli.
600 500
S 400
"S3 Soil-5 (S)
m
300 Soil-50 (S)
e t
J 200
■ leaves
■ stem
100 skin
Cu Fe Co Ni Cd Zn Mn Pb Cr Element
0
Fig. 4. The migration of HM elements from soil to solid parts of vine of vineyard Sabue: content of Mn in soil-5
and soil-50 is 2560 and 2640 mg/kg accordingly
4,5 4 3,5 1 3 1 M § 2,5 e ■ juce
nte 2 <3 15 J ■ Wine (kvevri)
1 Wine sealed
0,5 0
Cu Fe Co Ni Cd Zn Mn Pb Cr
Element
Fig. 5. The content of HM elements in juice and wine Saperavi
The increased content of copper and iron in leaves (Figures 6, 7). Most noteworthy, the iron content in Sa-compared to the soil is the result of spraying with cop- peravi wine, aged in Kvevri, decreased by only one or-per-containing pesticides contained in steel containers der and amounts to 4.25 in the Kvevri wine, 2.81 mg /
l in the sealed bottle. Perhaps, this insignificant increase in the concentration of iron is explained by its replenishment from the clay material of kvevri and the steel material of the tanks. Since it is known that 15-20 mg /
l of iron and more can enter the must and winematerials as a result of their contact with the metal parts of technological equipment and pipelines.
Fig. 6. The change of some HM concentration from soil to wine Kinzmarauli, obtained by European technology:1- Soil (5 sm); 2 - Soil (50 sm);3 - leaves; 4 - stem; 5 -skin; 6- juice; 7 - wine from tank; 8 - wine
sealed. Mukuzani site.
Fig. 7. The change of some HM concentration from soil to wine Saperavi, obtained by Kakhetian way:1- Soil (5 sm); 2 - Soil (50 sm);3 - leaves; 4 - stem; 5 -skin; 6- juice; 7 - wine from kvevri; 8 - wine sealed. Sabue site.
According to the recommendations of O.I.V. (1990) (International Organization of Grape and Wine) in wine should be contained no more than 0.3 mg / l Pb, 0.01 mg / l Cd, 1 mg / l Cu and 5 mg / l ZnO. Our data showed, that quantity of this elements in wine studied doesn't exceed this limits.
To compare with different wine from other countries Kinzmarauli and Saperavi contain HM in quantity, no exceeding MAC (table 2). Moreover, content of some elements in ten times less of MAC of these elements and their content in other wines.
Some authors believe that the source of heavy metals in wine could be the grapes, the processing the heavy metal content of wines. The variety and age of the grapes also play a role in the heavy metal content of wines. But most authors are inclined to the fact that the amount of heavy metals in wine varies depending on the particular grade, soil of the vineyard, climatic conditions, methods of combating with pests and diseases, methods of processing grapes and vinification. Penetration into the vine of heavy metals, formed as a result of man's production activity, i.e., by anthropogenic way, can lead to an increase of their content in wine.
Table 2
The comparative contents of HM in different wines of some countries, mg/l
H M Kindzma- rauli Georgia Sa- peravi,Geor-gia Pinot Noir, Finland [2] Caberne, Bela-rusia[14] Changli, China,Cab-ernet Sauvi-gnon Mavru d, Bulgaria [8] Chianti, Germany [16] Cabernet Sauvi-gnon, Turkey [15] MAC
Cu 0.04 0.07 0.039 1.62 0.37 0.31 0.28 0.51 5.0/0.1
Fe 2.50 2.19 1.80 1.59 2.66 13.35 15.0
Co 0.04 0.06 0.017 nd
Ni 0.08 0.08 0.16 0.08 0.91
Cd 0.003 0.007 nd nd nd 0.01 0.0008 nd 0.03
Zn 0.29 0.75 0.52 1.24 0.65 0.91 0.8 2.09 10.0
Pb 0.04 0.09 nd nd 0.15 0.009 nd 0.3
M n 0.45 0.42 1.40 3.98 2.81
Therefore recently there is rather heavy situation; in particular as U.K. researchers find the red and white wines from most European nations (13 countries) carry potentially dangerous doses of at least seven heavy metals [17]. The exceptions are Argentina, Brazil and Italy.
Conclusion
The concentration of all HM studied in represented Georgian red wines Kindzmarauli and Saperavi don't exceed the MAC. Most of HM in the grapes of wine Saperavi precipitates during fermentation into sediments, which is the reason for their significantly lower content in wine. Prevailed concentration of Cu and Fe to compare with other HM in Georgian wines is explained by its replenishment from the clay material of kvevri and partly the steel material of the tanks.
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