• Anthocyanin;
  • berries;
  • DPPH radical scavenging activity;
  • heating method;
  • juice concentration;
  • quality attributes


The effects of conventional (CV) and microwave (MW) heating on total soluble solid (TSS) content, total anthocyanin content (TAC), total phenolic content (TPC) and antioxidant activity of raspberry juice obtained from two cultivars of Amol (AM) and Siyahkal (SK) were scrutinised. Antioxidant activity of the juices was measured by 2,2 diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and expressed as EC50 value. In the both methods, the concentration rate constant for the juices was significantly decreased by increasing operational pressure from 12 to 100 kPa (< 0.05). A first-order reaction kinetic model was successfully fitted for the degradation of monomeric anthocyanins at all operating pressures. The results also showed that thermal treatment of MW compared CV in both SK and AM cultivars caused a lower decrease in the TAC, TPC and antioxidant activity. Moreover, the changes in trend of the antioxidant activities due to the thermal treatment were positively correlated with the TPC (= 0.74, < 0.05) and TAC (= 0.61, < 0.05).