Abstract:

In order to explore the effect of blanching treatment on enzymatic browning substances in litchi fruit pericarp
during heat pump drying process, the whole litchi was blanched in 0.3 g/100 mL citric acid at (95±3) ℃ for 90 s or 180 s
before drying and the enzymatic browning substances were determined. Due to a significant decrease in the activities of
polyphenoloxidase (PPO) and peroxidase (POD), total phenols, anthocyanin and red color index of dried litchi fruit pericarp
were highly prevented. No significant difference between blanching time and the activities of PPO and POD or the content
of anthocyanins in dried litchi after 60 h drying was observed.

Key words: litchi, blanching, polyphenoloxidase (PPO), peroxidase (POD), total phenol, anthocyanin