The influence of roasting degree on polyphenolic content in coffee

Kava je jedan od najčešće konzumiranih napitaka širom svijeta, zbog svojih fizioloških efekata i senzorskih svojstava. Danas je poznato da je kava također i bogati izvor polifenolnih spojeva koji imaju visoki antioksidacijski kapacitet i pokazuju pozitivne učinke na ljudsko zdravlje. Svrha ovog rada bila je spektrofotometrijski odrediti udjel ukupnih fenola i flavonoida, ukupnih flavan-3-ola (metodama s vanilinom i p-DAC reagensom), ukupnih tanina i procijanidina te odrediti antioksidacijski kapacitet ABTS metodom u 4 uzorka kave (Arabica i Cioccolatato, Coffea arabica te Robusta i Vijetnam, Coffea canephora), prženih u 3 stupnja. Temperatura prženja značajno utječe na udjel polifenola u kavi. Najveći udjel ukupnih fenola, flavonoida i procijanidina određen je u tamno prženim uzorcima Robuste. Udjel ukupnih flavan-3-ola u uzorcima Robuste, Vijetnam i Cioccolatato linearno se povećava povišenjem temperature prženja te je najveći u tamno prženoj kavi, dok je kod Arabice najveći u svijetlo prženoj kavi. Uzorci Vijetnama karakterizirani su najvećim antioksidacijskim kapacitetom, dok su uzorci Arabice imali najslabije izražena antioksidacijska svojstva.Coffee is one of the most frequently consumed beverages in the world, due to its physiological effects and sensory properties. Today it is well established that coffe is also a rich source of polyphenolic compounds, which exhibit good antioxidant properties and have beneficial effects on human health. The purpose of this work to determine spectrophotometricaly, the contents of total phenols, flavonoids, flavan-3-ols (using the Vanillin index and the reaction with p-DAC reagent), tannins and procyanidins, as well as their antioxidant capacity using the ABTS assay of 4 different coffee varieties (Arabica and Cioccolatato, Coffea arabica as well as Robusta and Vijetnam, Coffea canephora), roasted in 3 different roasting degrees. The roasting degree has significant influence on the content of polyphenols in coffee. The highest content of total phenols, flavonoids and procyanidinswas was determined in dark roasted Robusta coffee. According to the increased roasting degree the content of total flavan-3-ols in Robusta, Vijetnam and Cioccolatato coffee is increasing and it is the highest in dark roasted coffee, while in Arabica coffee it is the highest in green coffee. Vijetnam coffee was characterized with the highest antioxidant capacity, while the Arabica coffee exhibited the lowest antioxidant properties