Fruit growing
and viticulture of South Russia

Annotation

One of the most common ways to counterfeit the red wines is to adjust the coloring of cheaper white wine materials with both synthetic food colors (indigocarmine, carmoazine, etc.) and natural colors (extracts of blueberries, currants, etc.). The color characteristics of juice and wine products vary considerably depending on the type of feedstock, the technology of production, and the composition of the blend. In this regard, some unscrupulous manufacturers often use cheaper fruit and berry raw materials for coloring of grape wines. The purpose of the present research was the comparative characteristics of the phenolic complex and the optical characteristics of genuine red wines and falsifiers obtained using natural and synthetic dyes. The objects of research were table wine materials from Cabernet-Sauvignon and Rkatsiteli grapes, juices and fruit extracts, a mixture of synthetic dyes. The impact of natural and synthetic colourants on the optical characteristics of wine-making materials has been studied. Variation ranges were obtained for physical-chemical and optical parameters of model test solutions in terms of their colour intensity variation. The relation between colour intensity and phenolic compounds content along with monomeric anthocyanins was established (r=0.96 and 0.94, respectively). It was demonstrated that monomeric anthocyanins were absent in the model systems that contained synthetic adulterated winemaking materials. It is the significant difference in the qualitative composition of native and adaltirative wine materials: the total phenolic compounds and colour intensity index colourants were much lower in the coloured samples as compared to the established and recommended values for authentic wines, that allow to use these indicators in a set of criteria for identifying adulteration of wine products.

Annotation

A large assortment of grapes used for the production of rosé wines, along with technological processing peculiarities result in the final product with colour characteristics ranging from pale pink to dark crimson. Colour variability of rosé wines within the same product name of different batches may raise consumer�s doubts as to the origin and quality of a beverage. CIELab system is a promising way to wine colour quantitative expression with a view to its reproduction. The paper presents data on experimental comparison of organoleptic and instrumental methods for wine colour assessment. The study was conducted on samples of rosé table dry wines from �Cabernet Sauvignon�, �Saperavi�, �Bastardo Magarachsky� and �Sangiovese� grapes. Colour converter was used for reproduction of L *, a *, b * trichromatic coordinates. It was shown that wine samples from �Cabernet Sauvignon�, �Bastardo Magarachsky� and �Sangiovese� grapes were characterized by pastel colours, while Saperavi wines demonstrated pink and raspberry shades due to both the varietal characteristics of the grapes and the physical-chemical composition of the wines. The total content of phenolic substances in the samples of rosé wines can vary by 1.5-3 times, and range from 350 to 912 mg/dm3. Comparison of the visual and instrumental colour assessment methods demonstrated strong similarities between descriptive and colour expression of the studied samples color. The CIELab system can be used to mathematically express the colour of a wine, reproduce an image and colour, which can be used to regulate and manage the control of rosé wines.

Annotation

The direction of redox processes during biological aging of wine material is caused by the oxygen uptake, that is why its amount in sherry production is of decisive importance for the quality of the finished product. The aim of this work was to study changes in the volume components and physic-chemical characteristics of sherry base wines during biological aging, depending on the area of film overgrowing. The research was carried out on sherry base wines of �Aligote�, �Rkatsiteli� and �Kokur Belyi� grape varieties. Regulation of sherry yeast activity was carried out by introducing of tartaric acid as a metabolism inhibitor in experimental samples in the amount of 2.0 and 4.0 g/l. It was shown that the access of air oxygen at a time of biochemical transformation of metabolites provoked the non-enzymatic oxidative processes. Under the conditions of complete sherry film overgrowing in the base wines during aging, there is a decrease in the value of redox potential, optical dense D420, mass concentration of glycerin and all forms of phenolic substances, as well as a significant increase in the mass concentration of aldehydes, acetoin and diacetyl. When a discontinuous film overgrowing the increasing mass concentration of aldegides and their derivatives is observed in smaller amounts (in 1.4 and 2.6 times, respectively), in this case the values of optical dense (by 6 and 40 %), redox potential (by 6 and 17 %), and acetic acid increase. There is also an insignificant decrease in the concentration of glycerin, as a source of nutrition for sherry yeast, by 17 and 6 %, while in the control the content of the component decreases by 39 %. Under the conditions of incomplete film overgrowing on the surface of the base wines, the light fruit notes are observed against the background of aldehyde tones, as well as brown shades in color negatively affecting the tasting evaluation of the samples.

Annotation

Stabilization of wine means the removal of causes that provoke sediment formation in it, and giving stable transparency to the beverage during the warranty period using various technological operations. The aim of this work was to assess the impact of various technological methods at the stage of must (acidification with organic acids (citric, tartaric and malic), as well as must clarification with bentonite) on the tendency of base wines to crystalline haze and morphological features of crystalline sediment. The object of research was white dry base wines produced from the autochthonous grape variety Kokur Belyi, cultivated in the Republic of Crimea. It is established that the method of must acidification by adding citric acid provides a significant decrease in the temperature of saturation with calcium tartrate by 4.6 times compared to the control. Processing of must with bentonite also contributed to a decrease in the Tsat (�aT) indicator by 33.5-44.9 %. It was shown that methods of must acidification with tartaric acid, as well as must clarification with bentonite, provided a stabilizing effect towards crystalline calcium haze for young wine to the end of experiment (3 months). The characterization of crystalline sediment by visual assessment and microscopy showed that potassium bitartrate was present in all tested samples. At the same time, the volume of sediment and morphological features of crystals were significantly different: in experimental variants with introduction of citric, tartaric and malic acids, as well as in the control sample, an abundance of small transparent crystals of potassium bitartrate, which resemble �crushed glass� in shape, was observed. Presence of large crystals was noted in samples with introduction of bentonite at the stage of must, as well as malic acid in the amount of 2 g/dm3 . The results obtained are intended to support preventive measures in the production of wines to ensure their stability to crystalline haze.