Project title: "Isolation of pure cultures of the Saccharomyces cerevisiae yeast for Protected Designation of Origin (PDO) wines produced from Saperavi grape varieties on the territory of Georgia and study of their specific properties with the purpose of industrial use"

Funding organization: LEPL Shota Rustaveli National Science Foundation of Georgia, fundamental research project: FR-22-6630

Project supervisor: Nino Vephkhishvili

Project coordinator: Mariam Aleksidze

Scientific researchers: Giuli Andronikashvili

                                    Magda Davitashvili

                                    Vano Shiukashvili

Consultant: Giorgi Songhulashvili

Implementation period: 17.03.2023 - 17.03.2026.

 

Abstract

Georgian winemaking, which is an important branch of the country's economy, has massively switched to the use of dry commercial cultural yeasts imported from abroad, due to their ease of storage and consumption. However, this fact also has a negative side: wines produced from grapes of the same variety, but harvested in different places, are monotonous, have lost their individuality and, at the same time, have a high intrinsic value.

In order to solve these problems, to begin with, this three-year (17.03.2023 - 17.03.2026) project was created for only one - the oldest, most popular and technologically important - Georgian grape variety Saperavi.

The works of the first reporting period of the project have been completed: according to the plan-schedule, Saperavi grapes were harvested in ten micro-zones of viticulture and winemaking of Georgia. Red wines of protected designation of origin are made from Saperavi grown in these areas: Napareuli, Kindzmarauli, Kvareli, Akhasheni, Mukuzani, Akhoebi, Khashmi saperavi, Kakheti, Bolnisi, Tsinandali.

The sweet of the harvested grapes was fermented spontaneously - on its own wild yeast - in the red manner, together with Chacha; After removing the produced wines from chacha, the dominant pure cultures of Saccharomyces cerevisiaes corresponding to each wine were separated and purified from the remaining sediment with microbiological methods, which were sent for genetic identification to Great Britain, the Norwich Quadram Institute, the National Collection of Pure Strains and the Laboratory of Microbiology. PCR method was used to identify each of them. As expected, pure strains from different origins were found to be both different from each other (different origins) and related (same variety - Saperavi). 

So, in the first reporting period of the project, for the first time in Georgia, 10 new pure strains of Saccharomyces cerevisiaes were identified for 10 Protected Designation of Origin (PDO) wines produced from Saperavi grapes, which were even genetically identified at the DNA level.

Currently, the works of the second reporting period, provided by the project plan-schedule, are being carried out - the study of the microbiological and technological properties of the discovered pure cultures.

 

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Project title: The role of "native" cultural yeast in the formation of quality indicators of wine

Funding organization: Shota Rustaveli National Science Foundation of Georgia, master's project: MR-23-306

Master's student of Viticulture and Winemaking Program: Sophio Sidonashvili

Scientific supervisor: Nino Vephkhishvili

Consultant: Gaga Buishvili

Annotation

Saperavi is an ancient entrepreneurial grape variety, the wines made from which have high values: technological, commercial, and medicinal-prophylactic. In addition, the dry commercial cultured yeast imported from abroad adds a monotonous character to the wines of different localities, including wines made from Saperavi, as if it absorbs their individuality.

To solve this challenge, in recent years, TeSaU scientists and the university's partner company “Shumi” Winery, together with microbiologists of the Free University of Brussels, have bred their own pure cultures for red wines of three protected designations of origin: Napareuli, Kindzmarauli, Mukuzani, using technological and microbiological methods.

In Georgia, this kind of thing - fermentation of wine with its own yeast - is an innovation. "Shumi" started the production of such purely Georgian wines from these three sacred cultures, but, obviously, specialists are interested in the comparison of the quality indicators of newly bred, "native" pure strains and wines made on imported yeasts, which is served by this project.

The duration of the project is 10 months: December 2023 - October 2024 and is divided into several stages.

According to the tasks and plan-schedule, experimental wines were made from grapes harvested in the Napareuli, Kindzmarauli and Mukuzani microzones in the family cellar "Gorgora" in the village of Ikalto with 4 types of yeast: on the sacred culture corresponding to the wine of the place of origin (Napareuli, Kindzmarauli, Mukuzani), wild and 2 different commercial yeasts. , total, 12 options; The main physicochemical characteristics of young and 6 months wines were determined; For planted wines, additionally - the content of toxic substances: heavy metals and radionuclides, as well as common phenolic compounds, total and monomeric anthocyanins, antioxidant activity of wines; Organoleptic characteristics of experimental wines were studied: color, aroma, taste properties, harmony, body.

Currently, according to the results obtained based on the experiment, a master's thesis for public protection is being written; A report is being prepared to be presented at a scientific conference and also an article is to be published in an agricultural journal.