Ethyl carbamate, the ethyl ester of carbamic acid, has been identified in fermented foods and alcoholic beverages. Since ethyl carbamate is a probable human carcinogen, reduction of its content is important for food safety and human health. In alcoholic beverages, ethyl carbamate is mostly formed from the reaction of ethanol with urea, citrulline and carbamyl phosphate during fermentation and storage. These precursors are generated from arginine metabolism by wine yeasts and lactic acid bacteria. This review summarizes the mechanisms of ethyl carbamate formation, its impact on human health and methods used in winemaking to minimize its content. These approaches include genetic modification of Saccharomyces cerevisiae wine strains targeting pathways of arginine transport and metabolism, the use of lactic acid bacteria to consume arginine, direct degradation of ethyl carbamate by enzymes and microorganisms, and different technological methods of grape cultivation, alcoholic fermentation, wine aging, temperature and duration of storage and transportation.

In winemaking, malolactic fermentation (MLF), which converts L-malic acid to L-lactic acid, is often applied after the alcoholic fermentation stage to improve the sensory properties of the wine and its microbiological stability. MLF is usually performed by lactic acid bacteria, which, however, are sensitive to the conditions of alcoholic fermentation. Therefore, the development of wine yeast strains capable of both alcoholic fermentation and MLF is an important task. Using genome editing, we engineered a modified variant of the triploid wine yeast strain Saccharomyces cerevisiae I-328, in which the CAR1 arginase gene was replaced by the malate permease gene from Schizosaccharomyces pombe and the malolactic enzyme gene from Oenococcus oeni. Genome-wide transcriptional profiling confirmed the expression of the introduced genes and revealed a limited effect of the modification on global gene expression. Winemaking experiments show that genome editing did not affect fermentation activity and ethanol production, while use of the modified strain resulted in a tenfold reduction in malate content with simultaneous formation of lactate. The resulting wines had a softer and more harmonious taste compared to wine obtained using the parental strain. Inactivation of arginase, which forms urea and L-ornithine through the breakdown of arginine, also resulted in a twofold decrease in the content of urea and the carcinogenic ethyl carbamate in wine. Thus, the new strain with the replacement of the arginase gene with the MLF gene cassette is promising for use in winemaking.

The main problems of grape storage are berry dehydration and rot. One of the solutions to reduce rot and preserve the quality of grapes during storage is the use of aerosol treatment with calcium content before storing. The aim of the study was to evaluate the effect of physiologically active substances based on calcium in various concentrations on the quality and organoleptic characteristics of table grape cvs. ‘Italia’ during long-term storage. The effectiveness of the studied systems of treatment was evaluated according to the content of sugars and titratable acids, the activity of the redox enzymes of polyphenol oxidase and peroxidase, weight loss of bunch and organoleptic properties. The greatest effectiveness established by using preparation of Master Green Ca, Brentax KCa, and Brentax Ca (in concentration 150g / 20l). Experimental treatments significantly decreased the weight loss of bunch (less than 4%), and preserved organoleptic properties of berry at a high level (8.2-8.9 points). Decrease in the activity of oxidative enzymes had a positive effect on the quality of table grapes and contributed to its better preservation. The data obtained make it possible to rationalize the system of long-term storage of grapes by using of aerosol treatment with calcium-based preparation.

A grape plant is capable to adapt, grow and produce crops in different environmental conditions. At the same time, agro-climatic conditions of grape growing area have a significant effect on the product quality. Environmental climatic conditions of Crimea contribute to cultivating grapes from very early to late ripening varieties. Diverse range of abiotic conditions allows choosing an optimal terroir for the formation of necessary grape conditions depending on the application target. Significant spatial climate variability within the region makes it possible to evaluate the impact of environmental factors on biosynthetic and accumulative properties of grapes. The purpose is to study changes in the profile of carbohydrate-acid complex of wine grape varieties under the influence of agro-ecological growing conditions. Materials and methods. Study objects were white and red grape varieties growing in various viticulture and winemaking regions of Crimea. A research for grape plant response to the variability of environmental factors basing on a long-term comparative study of chemical composition of its fruits, determining the varietal biochemical identity and technological properties in a particular region, was carried out. Results and conclusion. As a research result, the cumulative effect of agro-ecological factors on the accumulation of components of carbohydrate-acid grape complex was established, and in particular years it was possible to identify the dependence between their quantitative content and individual environmental factors. Accumulation of the mass concentration of sugars in grape berry directly correlated with the Huglin index value (r = 0.7). With regard to the mass concentration of titratable acids, an inverse correlation was revealed with the Winkler index value (r = -0.59). A comparative analysis of the results shows that one grape variety grown under different climatic conditions may show different ability to synthesize the components of carbohydrate-acid complexes, determining its suitability for various output production. There is a direct correlation of the mass concentration of sugars on the average air temperature for the last month before harvest (r=0.70) within the variety. Виноградное растение способно адаптироваться, произрастать и давать урожаи в разнообразных природных условиях. В то же время агроклиматические условия территории возделывания винограда оказывают существенное влияние на качество продукта. Природно-климатические условия Крыма способствуют возделыванию винограда от очень ранних до поздних сортов, а широкое разнообразие абиотических условий позволяет подобрать оптимальный терруар для формирования необходимых кондиций винограда в зависимости от целей его применения. Значительная пространственная изменчивость климата в пределах региона позволяет оценить воздействие факторов среды на биосинтетические и аккумуляционные свойства винограда. Цель – изучение изменения профиля углеводно-кислотного комплекса винограда технических сортов под воздействием агроэкологических условий его произрастания. Материалы и методы. Объектом исследования являлся виноград белых и красных сортов, произрастающий в различных виноградо-винодельческих районах Крыма. Проведено исследование реакции виноградного растения на вариабельность экологических факторов на основе многолетнего сравнительного изучения химического состава его плодов, обусловливающих биохимическую индивидуальность и технологические свойства сорта в конкретной местности. Результаты и заключение. В результате проведенных исследований установлено совокупное влияние агроэкологических факторов на накопление компонентов углеводно-кислотного комплекса винограда, а в отдельные годы удалось выявить зависимости их количественного содержания от отдельных фактора среды. Установлена прямая зависимость накопления массовой концентрации сахаров в виноградной ягоде от величины индекса Хуглина (r = 0,7). В отношении массовой концентрации титруемых кислот от значения индекса Уинклера выявлена обратная зависимость (r = -0,59). Сравнительный анализ результатов, показывает, что один и тот же сорт винограда, выращенный в неодинаковых климатических условиях, может проявлять различную способность к синтезу компонентов...

In winemaking, malolactic fermentation (MLF), which converts L-malic acid to L-lactic acid, is often applied after the alcoholic fermentation stage to improve the sensory properties of the wine and its microbiological stability. MLF is usually implemented by lactic acid bacteria, which, however, are sensitive to the conditions of alcoholic fermentation. Therefore, the development of a wine yeast strains capable of both alcoholic fermentation and MLF is an important task. Using genome editing, we engineered a modified variant of the triploid wine yeast strain Saccharomyces cerevisiae I-328, in which the CAR1 arginase gene was replaced with the malate permease gene from Schizosaccharomyces pombe and the malolactic enzyme gene from Oenococcus oeni. Genome-wide transcriptional profiling confirmed the expression of the introduced genes and revealed a limited effect of the modification on global gene expression. Winemaking experiments show that genome editing did not affect the fermentation activity and the production of ethanol, while the use of the modified strain ensured a tenfold reduction in malate content with the simultaneous formation of lactate. The resulting wines had a softer and more harmonious taste compared to the wine obtained using the parental strain. Inactivation of arginase, which forms urea and L-ornithine through the breakdown of arginine, also led to a twofold decrease in the content of urea and the carcinogenic ethyl carbamate in wine. Thus, the new strain with the replacement of the arginase gene with the MLF gene cassette is promising for use in winemaking.