Aronia berries are famous for their high content of phenol compounds, particularly procyanidins, anthocyanins and flavonoids. The aim of this graduation thesis was to determine total phenolic content (TPC) and antioxidant activity (AA). In the study we compared aronia juices (trademarks Mediterra, Eden, Volovec and juice which was squeezed in the laboratory), dried aronia berries (trademarks Mediterra and Volovec) and aronia powder (trademark Mediterra and laboratory-prepared lyophilised powder). From dried aronia products we prepared water extract with 2 % acetic acid and ethanol extract. Using the Folin-Ciocalteu method, TPC was determined spectrophotometrically. The highest TPC was found in lyophilised powder, where chlorogenic acid equivalent was 241,8 µmol/g. We found no major differences in TPC content between dried berries and aronia juices. AA was determined with DPPH• radical scavenging method and the results were expressed as trolox equivalents. The highest AA was found in lyophilised aronia powder. The water extract contained 157 µmol/g, whereas the ethanol extract contained 197 µmol/g of AA. Between juices, the highest TPC content, 34 mM, and the highest AA content, 44 mM, was determined in Eden juice. The laboratory preparation of aronia powder showed that lyophilisation is good for preservation of bioactive components of dried aronia products.
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