Abstract:

The effect of three different blanching methods including microwave, steam and hot water treatments on the
quality of pumpkin leaves was studied by analyzing peroxidase (POD) activity, the contents of vitamin C, soluble protein
and oxalic acid, and color. Results showed that POD activity was obviously inhibited by all three blanching methods. The
relative residual POD activity was decreased to 7.10% after 60 s of steam blanching. The hot-water blanching showed that
POD activity was influenced more obviously by blanching temperature, which was significantly inhibited at 95 ℃ and
decreased to 4.85% after treatment at this temperature for 60 s. Relative residual POD activity of pumpkin leaves fell to
5.05% after microwave blanching at 480 W for 50 s. Hot water blanching retained the highest contents of vitamin C and
soluble protein, followed by microwave blanching and steam blanching. Lower content of oxalic acid, maximum value of
L* and minimum value of a*, confirming the best color of pumpkin leaves, were obtained by hot water blanching. Hot water
blanching for 60 s at 95 ℃ is the most appropriate way for pumpkin leaves. These results can lay a technical basis for deep
processing and utilization of pumpkin leaves.

Key words: pumpkin leaves, hot water blanching, microwave blanching, steam blanching