Fruit growing
and viticulture of South Russia

Annotation

The aim of this work was to study the changing type of titration curves of samples when receiving from a specific grapes varieties and wine mash depending on the production technology, and to compare these results with the results of the analysis by method of capillary electrophoresis and ion exchange method. We have developed the apparatus for automatic titration and structured a technique for quickly receiving and mathematic processing of product titration curves and to obtain the information about the content of sum of titrate acids. Such titration curves indirectly present the information on the overall proportion of metals cations and the ratio between various acids. The research objects are the wine materials and the worth from red grapes varieties, growing in the central zone of Krasnodar Region - Merlot, Kurchanskiy and Vladimir. In the micro vine-making shop of NCRRIH&V from experienced grapes varieties the mash have been received using the same technological scheme, excluding its the impact on the assessment of the varieties quality. The comparison of the experimental titration curves of mash from the initial grapes and received wines is carried out. It is shown that the content of titrate acids in the wine raw is higher than their content in the original material, and it increases in time when wine row is on the yeast sediment. It is established that malic-lactic acetic fermentation decreases in titrate able acidity. The salt part of the organic acids in the analyzed samples is found by titration curves. The results of the analysis were compared with data of capillary electrophoresis and they showed the high informatively of mathematical processing of the pilot data results. The results received in the research allow us to predict the final result of the analysis of grapes juice.

Annotation

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.

Annotation

Quality control and product safety directly depends on the competence of the testing laboratory. In connection with the improvement of the regulatory framework on quality and food safety increase in requirements for testing laboratories. The relevance of the article is connected with the introduction of a new version of the current international standard ISO / IEC 17025 �General requirements for the competence of testing and calibration laboratories�. The article analyzes the key changes of the document and the recommendations for their implementation in the activities of testing laboratories are given. The role of the requirements of science, legislation and the customer is defined. It is shown that the transition of testing Laboratories to the new standard version will allow to prove that they are acting professionally and capable to give the technically sound results. Elements of a risk-based approach are described, as well as the introducing requirements, based on production functionality. Suggested to develop the algorithm of risk management. Noted that new document regarding the requirements or processes, procedures, documented information and organizational responsibilities is more flexibility than that in the previous version. The area of the standard � laboratory activity is defined, the set of work for the laboratory is described, accent on a constant analysis of the professionalism of laboratory personnel is made. Aspects of competency confirmation for employees are described. The relevant issues of information technology are observed, the importance of using the specialized computer programs in the laboratory is defined that allow to carry out the complex statistical calculations and keeping of control charts. The responsibility for metrological traceability and its provision in the laboratory is specified. The rules of decision adoption for declarations about conformity are described. It is shown that new changes in laboratory activities will increase in the reliability of test results, and the effectiveness of quality control, and product safety and the high product competitiveness will provide.

Annotation

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 (�, 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.