Fruit growing
and viticulture of South Russia
Quality Management
A modern assortment of technical grapes should be formed take into account the correspondence of the genetic potential of cultivars with terroir of cultivation, and the changing biotic and abiotic environmental factors. Climatic changes observed in recent decades are global in nature and have a significant impact the processes occurring in the biosphere. The weather conditions in 2018 had significant differences in temperature and water regimes from long-term average values, which made it possible to identify the biological characteristics of the adaptation of the studied red grape varieties to prevailing abiotic conditions, as well as to evaluate the organoleptic, physical and chemical, and biochemical properties of the wine materials from these varieties. In terms of the number of anthocyanins and the content of phenolic substances, the wine materials of the studied varieties of AZES breeding surpass the control variant. The largest number of anthocyanins was found in wine material from Krasnostop AZOS grapes 1050 mg / dm3. In the wine material of the Cabernet AZOS, it was found 606 mg / dm3 in comparison with the Cabernet Sauvignon control 467 mg / dm3. There was no mathematically proven effect of the concentration of these substances the quality of wine in the experiment. The correlation coefficient between the content of phenolic substances and anthocyanins and the qualitative assessment of the studied table red wines was r = 0,14 and r = 0,17, respectively. In the experiment, the amount of extract given is statistically significantly correlated with the quality of red wine. As a result of mathematical processing of the data obtained during the research, the correlation coefficient between the content of sugarless extract and the qualitative assessment of table red wines was r = 0,68. According to the results of studies, it was found that wine materials prepared from grape varieties of the AZES breeding are not worse than the control of Cabernet Sauvignon according to organoleptic characteristics.
Organic acids are the main indicators of the chemical composition of grapes and wine, participate actively in the processes occurring in the wine formation, determine the acidic properties and taste of wines, the stability of products to turbidity, the intensity of redox processes is affected, and they are the markers of the authenticity of wines. The results of study of the behavior of one of the main grapes and wine acids malic acid are given in the paper. It is characterized by a sharp taste and can be transformed into lactic acid during biological acid reducing of wines. We analyzed the aqueous solutions of malic acid in concentrations from 0.549 103 to 1.792 103 mol / dm3 in the presence of strong electrolytes during continuous potentiometric titration with a coulometrically generated base in order to determine its effect the integral characteristics of wine quality. The titration of solutions was carried out against a background of 1.0 mol / dm3 KCl to maintain the constant ionic strength and conductivity in a setup consisting of a diaphragmless cell with generator and indicator electrodes. It has been hypothesized that in highly diluted solutions, malic acid and its anionic forms are in dimeric form. An analysis of experimental data and its theoretical interpretation show that malic acid is titrated as tetrabasic acid, and its existence in a stable dimeric form is confirmed. The nature of hydrogenic and intermolecular bonds is discussed. Critical points of malic acid solutions were found using the titration curves (ρ, pH0, pH1, t1, t2 etc.) whose values can be used for the integral quality control of wines. It is proposed to use the results obtained to improve methods for assessing quality and identifying the grape raw materials and the wines.
The varietal characteristics of the grapes are of great importance when choosing the direction of their use. These features include the color of the grape and its flavor characteristics, the presence of coloring agents in the berry, the ripening period, etc. Features of the variety are reflected in the quality of the wine and its organoleptic properties. The physical and chemical composition of the must and wine varies greatly depending on the quality of the grape and its variety, the natural conditions of the cultivation area, agricultural technology and technology of wine preparation. So, different grape varieties have different amounts of sugar, organic acids, minerals, enzymes and vitamins in the berries. This paper presents the results of a comparative analysis of must and wines prepared from white grape varieties of interspecific origin, grown under the same conditions. The objects of research were must and wines from white technical grape varieties of the ARSRFVW breeding Tsvetochny, Donus, Platovsky, Stanichny, Hungarian varieties Crystal, Bianka, Lakhed mezesh and the Western European Aligote grape variety grown in the vineyards of the Novocherkassk department of the Experimental Field located at the SRFVW. The research was carried out on the basis of the wine-making technology laboratory and the quality control of grape and wine products laboratory of SRFVW. Experienced wines were prepared under micro-winemaking conditions according to the classical technology for dry white wines using the technological equipment for grape processing. The organoleptic analysis of the wines under the study showed that the experimental samples of wines from grape varieties of Aligote, Lakhed Mezesh and Stanichny had the brightest varietal aroma and full harmonious taste and received a high tasting score (8.7 points). It has been established that the chemical composition and organoleptic properties of wines made from grape varieties of interspecific origin largely depend on the varietal characteristics of the grapes.
An experimental study of the behavior of dilute (c < 2×10-3, mol/dm3) aqueous solutions of malic acid in the presence of strong electrolytes in the process of continuous potentiometric titration with an electrogenerated base was performed. A phenomenological model of malic acid ionization is proposed, based on the assumption that its molecular and ionized forms exist in dimeric forms in solutions, including highly diluted ones. The proof of the correctness of the proposed model was performed by solving two mathematical models and testing them experimentally. The first classical model was that malic acid under experimental conditions is in monomeric form and in the process of titration is successively ionized by two steps. The second model was based on the fact that malic acid, like its anionic forms, is in aqueous solutions in a stable dimeric form and is titrated as a four-base acid. Ionization constants are found for each of the models, and the relationship between them is described. For the second model, it is shown that the process of ionization of malic acid in the third and fourth stages is difficult due to the fact that protons are located in a ring of carboxyl groups and are titrated much more difficult than the terminal ones, since their bond with oxygen atoms is strengthened during titration. Distribution curves of the assumed molecular and ionic forms of malic acid formed during titration are constructed, and the nature of hydrogen and intermolecular bonds is discussed. The influence of malic acid the appearance of wine titration curves was revealed. The results of comparing the ionization constants of dimernic forms of tartaric, malic, citric, formic, lactic, succinic and acetic acids found by this method are presented. The results obtained are used in titrimetry methods for evaluating the quality of grape raw and wines.
The influence of systemic application of top-dressing for Chardonnay and Merlot grapes with water solutions of special organomineral microfertilizers the biological productivity of plants, the chemical composition of berries and the quality indicators of wine materials is studied. In 2016-2017, special organomineral composition containing amino acids, ascophyllum nodosum algae extract and the trace elements (B, Cu, Fe, Zn, Mn, Mo, Co) were used in the Black Sea zone of the Krasnodar Territory. Significant influence of agricultural ways the number of fruit-bearing shoots, inflorescences and growth activity of grapes was revealed. In comparison with the control variant (without preparations), the number of fruit-bearing shoots per bush increased by 7.4-19.2 % and inflorescences by 3.7-12.5 %. In the summer period, against the background of the negative effect of abiotic factors, sufficient hydration of cells in grape plants with preparation`s treatments was achieved by increasing in the connected form of water. The photosynthetic activity of the leaves was maintained due to the formation of a more powerful palisade mesophyll. Fertilizing with organomineral microfertilizers helped to strengthen the reproductive function of plants (an increase in yield by 19-30 %, depending on the variety), and had a positive effect on the commercial quality of grapes. In the juice of grapes a sugar content is increased in comparison with the control variant by 17 % for Chardonnay and 14 % for the Merlot, and as a result, the volume fraction of ethyl alcohol in wine was significantly higher compared to control samples (1.3% vol.). Top dressing with organomineral microfertilizers contributed to a decrease in the mass concentration of titrated acids in the juice of grape berries by 13 %. A higher organoleptic value of wine materials from grapes grown on the background of organomineral top dressing was given. The samples had more complete varietal nuances and long good taste.