The objective of the study was to analyze the effect of total content of minerals in waters on the effectiveness of extraction of polyphenols and flavonoids and on the antioxidant properties of brews from leaves of green and black tea, leaves of peppermint, chamomile inflorescences, leaves of sage, and flowers of lavender. The process of brewing was conducted at an initial temperature of 95 °C, under cover, for 15 min, with the use of 10 waters differing in terms of mineral components. The content of total polyphenols and total flavonoids was determined in the brews obtained. The antioxidant properties were assayed with the use of stable DPPH radicals and Ferric Reducing Antioxidant Power (FRAP) reagent. A significant effect of water mineralization on the extraction of phenolic compounds and on the antioxidant properties of the brews obtained was observed. In the majority of cases, the highest concentrations of polyphenols and flavonoids were obtained in brews prepared with the use of deionized water and waters with medium levels of mineralization. It was also demonstrated that there was a significant reduction of antioxidant properties in brews prepared with the water that had the highest level of mineralization (2896 ppm), at 70% and 93%, respectively, for green and black teas.
Keywords: antioxidant activity; flavonoids; herbal brews; mineral compounds in water; polyphenols.