In Master's thesis we determined the antioxidative activity of yogurt with added flower honey and spruce tips extract and the activity of individual ingredients (yogurt, flower honey with spruce tips extract) in yeast Saccharomyces cerevisiae as a model organism. Additionally, antimicrobial activity of yogurt, flower honey with spruce tips extract and the spruce tips extract in selected microorganisms was investigated. After a two-hour exposure of yeast cells to water and ethanol working extracts, we determined the antioxidative activity of the tested substances by measuring the intracellular oxidation of the 2',7'-dichlorodihydrofluorescein oxidized dye. The antimicrobial activity was determined by colony count method and by determining the percentage of growth inhibition. The results showed that water extracts of flower honey with spruce tips extract and the combinations of yogurt with added ingredients have a more positive effect on reducing intracellular oxidation of yeast cells than ethanol working extracts. The thesis also discovered that yogurt does not contribute to reducing intracellular oxidation, but the addition of flower honey with spruce tips extract does. Antimicrobial tests show that yogurt (at 5 °C) had a bactericidal effect on Listeria monocytogenes, Staphylococcus aureus and Pseudomonas aeruginosa. Antimicrobial activity was found in flower honey with spruce tips extract, but the spruce tips extract itself inhibited the growth of L. monocytogenes and S. aureus. None of the tested substances had an antimicrobial effect on Kluyveromyces lactis. For the studied concentrations of yogurt with added flower honey and spruce tips extract and for the content of the added ingredients that got the best sensorical score, we confirmed antioxidative activity on the cellular level and antimicrobial activity in certain species of microorganisms.
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