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17CHEMICAL SCIENCES
SOME MINERAL COMPONENTS IN GEORGIAN RED WINES SAPERAVI AND KINDZMARAULI
Kekelidze N.
Kekelidze T.
Akhalbedashvili L.
Mirtskhulava M. Maisuradze G.
Kvirkvelia B.
Tsotadze G. Liparteliani V.
Ivane Javakhishvili Tbilisi State University
Tbilisi, Georgia
ABSTRACT
The aim of this work is to determine the mineral components of red wines Saperavi and Kindzmarauli from eastern Georgia, produced by winery "Khareba".
On the base of ISO methods was worked out standard operation procedure of sampling, preparing and chemical analysis of all parts of vine (leaves, stems, pulp, juice, skin and seeds) and soil samples from two different depths.
The study make it possible to trace the migration of contained in the soil or introduced into it the elements up to the final product - wine. Initial results indicate on non homogeneous distribution of Na +, K +, Ca2 +, Mg2 +, PO43-, SO42" ions along the whole chain from the soil to wine.
Keywords: Georgian red wines, mineral components, chemical analysis
Introduction
Wine contains more than 600 natural substances. Among them about 20 organic acids and their salts, tens of aromatic alcohols and ethers, amino acids, phenolic, minerals, some of enzymes, vitamins and minerals that promote normal digestion and metabolism [1-4]. In common the components of wine may be classified by following way [5]:
1. Compounds, which are the components of grapes (water, bound acids, sugars, nitrogen-contained compounds, phenols, pectins, mineral components, vitamins, aromatic matters);
2. Compounds, formed in fermentation process (ethanol, high alcohols, polyhydric alcohols, bound and free acids, aldehydes, ketones, ethers and carbon dioxide).
There are many papers describing the effect of volatile and polyphenolic components on the taste, smell and therapeutic properties of wine, but almost in all works these components are considered as a mixture, without an analysis of its individual components [1-4]. Complete chemical analysis at the present state is not available and it is possible to be satisfied with only the definition of the most important components of wine, in particular, mineral part, which affects fermentation temperature, and subsequent reactions [6].
The content of mineral compounds is very various and, conventionally, they can be divided into cations and anions: cations are K+, Na+, Ca2+, Mg2+, Cu2+, Fe2+, Fe3+; anions -PO43-, SiO32-, CO32-, SO32-, CL-, J-, NO3-[7].
Insistence of must on solid parts of the bunch, especially on ridges, sharply increases the content of mineral substances. The red wines, produced by insisting on pulp, the content of K, Na, Mg and other elements is approximately twice greater than in whites. Conversely, the calcium content in red wines is 50% lower than in whites. This is due to the formation of insoluble tanat of calcium, which precipitates.
During fermentation of the must the total content of minerals is significantly reduced as a result of the precipitation the salts of Ca, K, Mg and other metals. The assimilation by yeast of phosphoric acid, Pb, As, Zn, Cu, Fe and other elements also leads to a decrease in mineral content in wine.
Some elements are precipitated at aging the wine. Cu and K isolated as oxalate and tartrate, Fe and Pb by reaction with phenolic compounds form heavy soluble tanat or tannin-protein compounds and precipitate.
But content of mineral components significantly depends on composition of soil, on contamination degree of water and atmosphere, i.e., on environment.
So, minerals are taken up by the vine from the soil. The main part of them formed as a result of organic materials' digestion. They present in wine in inorganic and organic forms and usually make up approximately 0.2 to 0.6% of the fresh weight of the vine. Potassium is the most important mineral from the mineral compounds, mentioned above. It accounts for 50 to 70% of the cations in the juice. During ripening, the potassium content of the grape increases. Its movement into wine leads to the formation of potassium bitartrate, which reduces the acidity and increases the pH of juice. It should
be noted that the tartaric acid salt of potassium is involved in wine instability problems.
The aim of this work was to trace the migration and transformation of main mineral components, such as potassium, sodium, phosphates, sulfate, chloride, and others from soils of Mukuzani and Sabue vineyards (Kakheti, Georgia) through vine (stem, skin, pulp, seed) in juice and then in wines Saperavi and Kindzma-rauli, using AAS, photocolorimetry, spectrophotometry, conventional chemical analysis methods.
Materials and Methods
Samples of Mukuzani and Sabue soils, vine (stems, skins, seeds) and young and aged wines Sa-peravi and Kindzmarauli were collected. The test wines were obtained directly from producer - winery "Khareba". All obtained samples were stored at 40C -60C. The soil of the regions is well drained, with medium clay texture, soft friable consistency, high water retention capacity, and absence of stones. A microwave oven (Berghof Speedwave MWS-3; Berghof, Eningen, Germany) and specially made Teflon vessels were used for the digestion procedure. The microwave acid digestion procedure was performed as follows: after weighing 0.20 g of samples for each soil, the samples were conveyed into pressure-resistant PTFE vessels, followed by the addition of 4 ml of the acid mixture HNO3 - HCl - HF with ratio 1:3:1. The digested samples were transferred to 50 ml volumetric flasks, and bi-distilled water was used to set the final volume.
The stems, skins, seeds were treated in accordance with GOST 26926-86 for following chemical analysis: washed in running water, dried at the room temperature, grinded in mortar, and ashes. After dry mineralization the sample was alloyed with soda, leached and treated by HCl. Silica was removed from solution and determined gravimetrically. In filtrate were determined
potassium, sodium, calcium, magnesium, aluminum, phosphor and chlorine, using photometric, flame spec-trophotometric, volumetric, complexometric, mercuri-metric and turbidimetric methods in accordance with ISO (ISO 762:2003; ISO 763 2003) and GOST (2642885; 26425-85;30407-96). Cl- and SO42- ions were determining from aqueous extracts.
All the stock solutions were prepared in high-density polyethylene containers and were kept in refrigerator at 40C-60C. Nitric acid (HNO3 62%), hydrochloric acid (HCl 36%), and hydrofluoric acid (HF 40%) were of analytical grade. To ensure accuracy, all the analyses were repeated three times.
Results and discussion
The mineral substances necessary for the successful cultivation of vines are supplied to the soil in a vineyard either by the bedrock, and vine roots are capable of reaching down to considerable depths to find them. Their content in a given wine varies depending on the amount of rainfall in a particular area. In red wines their greater amount is extracted from the solid matter of the grapes during the maceration and fermentation processes [8].
A high dispersion of the contents of elements observed in wines was widely described in the literature [9-12]: grapes, must and wine contain dissolved non-organic salts, and these salts are minerals or metal elements, which occur naturally in grapes, which attach to berry surfaces as a result of practice of viticulture, or which enter the wine during the vinification process.
Our results showed that the mineral compositions of studied wines and soils were interrelated. Composition of the main components of soil samples researched is almost the same for both Mukuzani and Sabue vineyards and a nearby environmentally clean zone (Table 1).
Table 1.
Results of soil analysis, mas. %
No SiO2 Al2Os P2O5 CaO MgO K2O Na2O Cl- , mg/100g (aq. extract) SO42-, mg/100g (aq.extract) Humus
1 51.47 11.67 0.15 10.79 0.75 1.0 1.6 2.66 3.0 1.84
2 56.33 13.21 0.13 6.97 1.79 1.0 1.5 2.31 2.8 2.01
3 55.76 16.65 0.26 3.55 0.38 1.9 2.0 3.37 3.0 2.83
4 57.11 13.12 0.25 3.16 3.38 1.8 2.0 2.67 2.4 2.74
5 57.69 17.01 0.22 3.06 0.56 1.4 1.6 2.67 3.0 3.42
1-Mukuzani vineyard, depth 5sm; 2- Mukuzani vineyard, depth 35sm; 3- Sabue vineyard, depth 5sm; 4 - Sabue vineyard, depth 35sm; 5 - ecologically clean area
Consequently, the vineyards are not contaminated by any external introduced elements. At the same time the soil contained essential major elements for grapevine growth. It must be note that Mukuzani vineyard is distinguished by a high, close to the maximum, content of calcium (norm for soil ~ 6%).
In contrast to the soil, in the changing the content of the main macronutrients in bunch of grapes in the row: stem, leaves, skin, pulp, seeds no regularity is not observed (Figure 1). The content of magnesium and calcium in leaves are almost an order of magnitude higher than in stem. The amount of aluminum and silicon in particular decreases in the row: stem, skin, pulp, seed, and then rises sharply in the leaves - roughly an
order of magnitude for silicon (Figure 2). The phosphorus content in the leaves also increased. Conversely, the potassium content gradually decreases from the stems of grape to the leaves and the seeds.
It is known that potassium is the main and most abundant cation in the wines [1]. A variety of grapes, soil and climatic conditions, time of harvest, the temperature of fermentation and storage, and the pH affect the amount of potassium in wine [10]. Its concentration in wine ranges from 200mg/l to 2000mg/l [2]. The content of potassium in studied wines decreases from 20000mg/kg and 14000mg/kg in stems of Mukuzani and Sabue accordingly, 8000mg/kg and 9500mg/kg in pulp, 3000mg/kg and 4000mg/kg in leaves to
730mg/kg and 800mg/l in Kindzmarauli and Saperavi wines accordingly (Fig.1-3).
The high level of potassium is observed in Brazilian (1032mg/l), Californian and Spanish wines [13-15],
Sodium is less common in wine, but at the same time is the main extracellular cation, and play rather big role in maintenance of the acid-base balance and in osmotic regulation [6, 9]. Its content varies in the range 10mg/l-300mg/l. In Kindzmarauli and Saperavi wines
but in Turkish and Chinese wines potassium level is lower (~500 mg/l) [9, 16]. Our data lay between their results.
■ Si Al P
Ca
Mg
K
Na
sodium was found in lower concentrations (60mg/l). In addition to being a natural element found in grapes, sodium can be added to wine during sulfur dioxide additions when SO2 is added in the form of sodium metabisulfite (Na2S2O5).
Si Al
Ca Mg K Element
Na P
j? 25000 "SB £= 20000 4-t
n
Si 15000 e n
<3 10000
5000 0
. V"
"V
////
Figure 1. Mineral composition of different parts of vine
Figure 2. Content of some main elements in vine leaves
<3 300 200 100 0
Si Al Ca
Mg K Na Element
I Kindzmarauli Saperavi
Figure 3. Content of some main elements in Kindzmarauli and Saperavi wines
P
S
This principal component can be related to soil composition and winemaking process [10].
The concentration of magnesium in Kindzmarauli wine is 88mg/l, but in Saperavi no more than 43.24mg/l. In accordance with authors of [7] Mg in Cabernet Sauvignon, grown in Turkey was varied in range 27mg/l-68mg/l, in Cabernet Sauvignon (80.30mg/l-98.52mg/l) and Merlot (79mg/l-90mg/l) wines produced in Southern Brazil [17] and Cabernet Sauvignon (80mg/l-160mg/l) wines produced in China [16]. The Mg content in wines can be attributed to a number of factors including the soil composition, pH, the time, the temperature of storage, and the rate of pressing [18]. Reducing the amount of mineral compounds continues during processing and aging of wine material [19]. The yeast cells partly utilized potassium, calcium and sodium.
Potassium is precipitated in the form of tartar. The concentration levels of calcium in studied wines: 50mg/l in Kindzmarauli and 69mg/l in Saperavi - were close to the values found in other researches [9,10,15]. Averaging about 80mg/l, calcium can cause tartrate instability in wine.
pH of juice from Mukuzani vineyard is equal 2.92, but from Sabue vineyard - 3.20. pH of Saperavi wine, obtained by Kakhetian method of winemaking (in pitcher) reaches 3.44, and for semi-sweet wine Kindzmarauli pH not more than 3.00. Those values of pH is more convenience for binding of sulfur dioxide with acetaldehyde, because rate of this reaction increases with pH growth [7].
Among anions in studied wines preferentially were found sulfates (200mg/l -260mg/l) and phosphates (about 145 mg/l) followed by anions of chlorine and silicon. In wines sulfates occur in amounts of 400mg/l -1000 mg/l [7]. Usually the vine takes sulfates in trace quantities from the soil as remnants of nitrogen, potassium or magnesium fertiliser. The most amount of sulfates falls into the wine, especially white wine, from the sulfuring added to the grape must. Phosphates get in the soil in an acceptable form through the process of
erosion. A smaller amount also comes from phosphoric fertilisers.
Conclusion
The main elements like K, Ca, Mg and Na were abundant in our wine samples like in other different red wines studied. These elements are also important for the geographical classification of wines. During ripening, the potassium content of the grape increases. Its movement into grapes leads to the formation of potassium bitartrate, which reduces the acidity and increases the juice pH. Original results indicate on nonhomoge-neous distribution of Na +, K +, Ca2 +, Mg2 +, PO43-, SO42-ions along the whole chain from the soil to wine.
Perhaps, the study of mineral content of "Khareba" red wines presented here can be used to obtain a successful regional classification for future studies.
,,This work was supported by Shota Rustaveli National Science Foundation (SRNSF) [DI/38/7220/14, The Complex Study of Antioxidantes and Mineral Components in Georgian Red Wines by Modern Physical-chemical Methods]"
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NATURAL ADSORBENTS FOR CLEANING WATER FROM
ARSENIC
Akhalbedashvili L.
Janashvili N.
Kvatashidze R.
Todradze G.
Loria N.
Jalaghania S.
Al.Tvalchrelidze Caucasian Institute of Mineral Resources, TSU, Tbilisi, Georgia;
ABSTRACT
The problem of contamination of soil, surface and ground water with Arsenic compounds are particularly acute for a lot of countries.One of the best solutions to the problem of cleaning natural waters, is to use the sorption methods. In submitted work studies, we first compared the adsorption of As(III) in cationic (As3+) and in anionic (AsO33-) forms from water solutions on different adsorbents, such as diatomite, activated carbon and especially natural zeolites clinoptilolite and mordenite from deposits of Georgia, in initial and modified forms.
The dependence of the exchange capacity of arsenic from the form of finding it in a solution, to the type of modification of the zeolite, pre-treatment temperature and the concentration of the model solution was established. It is shown that the two mechanisms work in the adsorption of cationic form - ion exchange and donor-acceptor; during the adsorption of the anionic form AsO33- pre-dominates the physical adsorption.
Keywords: Arsenic (III), adsorption, zeolites, diatomite
Introduction
Widespread environmental contamination with Arsenic leads to the intensive study of its behavior, in particular the migration in natural environments. Elevated concentrations of Arsenic in groundwater used for drinking water supply are causing chronic diseases in humans, conditioned by anthropogenic pollution of soil and rocks, and high natural levels of Arsenic in the water-bearing rocks.
Over 70 million people in Eastern India, Bangladesh, Vietnam, Taiwan, and Northern China have been victims of Arsenic poisoning [1-5]. The USEPA has classified Arsenic as a "Class A" carcinogen [6] and recently reduced the Maximum Contaminant Level (MCL) in drinking water from 50 ppb to 10 ppb. To meet those drinking water standards, small water utilities need low cost and effective Arsenic removal techniques. Artificial pollution with Arsenic is associated with the use of pesticides containing this element as
[Pb3(AsO4)2], atmospheric deposition, mining processes - which uses Arsenic (gallium arsenide).
More widespread forms of Arsenic in the environment are arsenate [AsO43-, As (V)] and arsenite ions [AsO33-, As (III)]. Arsenite is more mobile and more toxic form of Arsenic [7]. In general, toxicity increases in the sequence: organic arsenical<As (V) <As (III)<arsine (AsH3) [8]. Adsorption of Arsenic on a mineral surface is a very important process, which controls its biological accessibility in natural systems. The biological accessibility and toxicology of Arsenic depends as on its forms and from a great quantity of chemical, physical and biological factors - which include pH, mineralogy, oxidative-reduced potential, microbiological population, presence of the ligands of different nature [7].
There is an intensive research worldwide to improve established techniques and to develop novel treatment technologies for removing Arsenic from
