Selection of 80 newly isolated autochthonous yeast strains from the Tikves region of Macedonia and their impact on the quality of red wines produced from Vranec and Cabernet Sauvignon grape varieties.

The main objectives of this study were to (i) isolate newly autochthonous yeast strains from the Tikves region of Macedonia and (ii) test their impact on the quality of red wines from Vranec and Cabernet Sauvignon grape varieties. The newly isolated yeast strains were obtained by spontaneous fermentation of grape must from Vranec and Cabernet Sauvignon varieties collected from ten different micro-regions in Macedonia. The grapevines from both varieties grown in "Barovo" micro-region were the richest sources of yeast strains. In addition, the molecular identification and typing of strains were also carried out. The monomeric anthocyanins, polyphenolic content and other oenochemical characteristics of the wines were also compared with the wines from commercial yeast strain "SiHa". The Vranec wine from yeast strain F-8 and Cabernet Sauvignon wine from yeast strain F-20 had significantly (p<0.05) higher concentrations of monomeric anthocyanins and total phenolic compounds than other wines.

The impact of some wine-making practices on the quality of Vranec red wines from Macedonia produced by the newly-selected local strain "F-78".

The impact of enological practices (temperature, flipping and the inoculation amount of newly selected yeast F-78 from third-stage selection) on the level of monomeric anthocyanins, total phenolic compounds and the overall taste of fifteen red wines from Macedonian Vranec grape variety were studied. The most important factor which affects the level of monomeric anthocyanins was temperature. The inoculation amount had a positive influence on the phenolic extraction. More inoculation amount leads to faster ethanol formation and acceleration of the anthocyanins extraction. The flipping of the must during fermentation was controversial. The best wine-making procedure for production of the typical for the region high-extractive aged wines included a fermentation temperature of 20-24°C, intensive flipping (5-6 times/24h), and inoculation quantity 3-4% and a fermentation on 20°C, medium flipping (3-4 times/24h) and inoculation quantity 3-4% for production of commercial, young and easy to drink "Beaujoulais" wines.

Targeted analysis of bioactive phenolic compounds and antioxidant activity of Macedonian red wines.

Phenolic composition of twenty-two Macedonian red wines, including ten autochthonous monovarietal Vranec wines produced with different yeasts for fermentation, and twelve wines from international varieties (Syrah, Merlot and Cabernet Sauvignon) from different wine regions was studied. All wines presented relatively high value of total phenols and antioxidant activity. A total of 19 phenolic compounds were identified and quantified using HPLC-DAD and among them, malvidin-3-glucoside and its derivatives were the major compounds, followed by the petunidin derivatives, while caftaric acid was the predominant cinnamic acid derivative in all wines. The anthocyanin content was mainly affected by the grape variety and to a less extent by the yeast used in fermentation. In particular, the use of locally isolated yeasts affected higher amount of anthocyanins and phenolic acids compared to the wines fermented with commercial yeasts. Principal Component Analysis showed a satisfactory grouping of red wines according to the grape variety.