The chemical composition and quality of eight pure cold‐pressed oils and two blend oils from Macedonia were examined in this work. The highest level of oleic acid was determined in apricot kernel oil and rapeseed oil with abundance of 70.9 and 59.2%, respectively. The highest level of polyunsaturated fatty acids was seen for flaxseed and hemp seed oil with abundance of α‐linolenic acid of 55.1% for flaxseed oil and linoleic acid of 57.4% for hemp seed oil. Apricot kernel oil and roasted sesame seed oil had the highest oxidative stability with induction times of 7.6 and 10.9 h. Apricot oil, hemp seed oil, and flaxseed oil had the highest level of total vitamin‐E‐active compounds with 58.8, 58.1, and 69.7 per 100 g of oil with predomination of γ‐tocopherol. The highest peroxide number was detected in blend oils (oil 2 and oil 8) with values over 10 meq O2/kg of oil. The highest FFA was detected in rapeseed oil (1.57%). Roasted and unroasted sesame seed oils had relatively high specific extinction (K232 values 3.55 and 3.33, respectively). However, the highest UV extinction had a blend of pumpkin seed oil and sunflower oil with a value of 3.84. Practical applications: The results of this study can be applied for determination of the most important major and minor components responsible for quality evaluation of cold‐pressed oils. Statistical results indicated a strong relationship between the level of monounsaturated fatty acids in the oil and their oxidative stability. The level of tocopherols and other vitamin‐E‐related compounds was in strong relationship with the antioxidant activity of the oils measured by the DPPH method. Phytosterols, as minor compounds present in the oils, did not contribute significantly to the total antioxidant potential of the oils but, their levels in particular oils, together with fatty acids, can be useful and reliable markers for the purity of the oils and determination of the composition of blends. Score plot of fatty acid profile, induction time, peroxide number, FFA, specific extinction, total phenolic compounds, total flavonoids, DPPH and TEAC assay, vitamin‐E‐active compounds, and phytosterols of ten cold‐pressed edible oils from Macedonia.
a b s t r a c tThe main objectives of this study were to (i) isolate newly autochthonous yeast strains from the Tikveš 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.
a b s t r a c tThe 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/24 h), and inoculation quantity 3-4% and a fermentation on 20°C, medium flipping (3-4 times/24 h) and inoculation quantity 3-4% for production of commercial, young and easy to drink ''Beaujoulais" wines.
The bioactive compounds and "in vitro" antioxidant activity measured by three antioxidant assays of some traditional and non-traditional cold-pressed edible oils from Macedonia were object of this study. The fatty acid composition showed dominance of monounsaturated oleic acid in "sweet" and "bitter" apricot kernel oils with percentages of 66.7 ± 0.5 and 57.8 ± 0.3%, respectively. The most dominant fatty acid in paprika seed oil was polyunsaturated linoleic acid with abundance of 69.6 ± 2.3%. The most abundant tocopherol was γ-tocopherol with the highest quantity in sesame seed oil (57.6 ± 0.1 mg/100 g oil). Paprika seed oil, sesame seed oil and sweet apricot oil were the richest source of phytosterols. DPPH assay was the most appropriate for the determination of the antioxidant activity of cold-pressed sunflower oil due to high abundance of α-tocopherol with a level of 22.8 ± 1.1 mg/100 g of oil. TEAC assay is the best for the determination of the antioxidant activity of sesame seed oil and paprika seed oils as the richest sources of phenolic compounds. β-carotene assay was the most suitable assay for oils obtained from high pigmented plant material. Triacylglycerols and phytosterol profiles can be used as useful markers for the origin, variety and purity of the oils.
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