Kinetika termalne degradacije ukupnih polifenola, flavonoida, antocijana i pojedinačnih antocijanatokom pripreme dve vrste džema od divljih kupina

Abstract

Fresh wild blackberries were processed into sugar and sugar-low jams at high temperatures (90, 95, 100 and 105 °C). Total phenolic (TP), flavonoid (TF), anthocyanin (TA) contents and antioxidant activity, as well as the content of individual anthocyanins were significantly affected by the temperature, heating time and jam type, with the largest retention in the sugar-low jam prepared at 90 °C for 5 minutes and with the largest decrease in the sugar jam prepared at 105 °C for 30 minutes. Cyanidin- 3-rutinoside was found to be the most stable and cyanidin-3-malonylglucoside was found to be the least stable in sugar-low jam. In sugar jam, cyanidin-3-rutinoside and cyanidin-3-malonylglucoside have shown a relatively equable stability, while cyanidin-3-glucoside was the least stable. In the temperature interval from 90 ºC to 105 ºC, the degradation of total anthocyanins in both sugar and sugar-low jam types followed the first-order reaction, with activation energies (Ea) of 57.4 kJ/mol and 48.0 kJ/mol, respectively. The half-life values (t1/2) of total anthocyanins ranged from 6.6 to 15.9 minutes for the sugar jam and from 13.1 to 27.7 minutes for the sugar-low jam. The degradation of total anthocyanins is more susceptible to temperature elevation in the sugar jam compared to the sugar-low type.