Abstract:In order to explore suitable quick-frozen preprocessing techniques of hami melon (Cucumis melo var. saccharinus), hot water blanching (temperature 80℃, 90℃, 100℃; time 0.5~4 min), 100℃ steam blanching ( time 0.5~4 min ) and high pressure processing ( pressure 100 MPa, 200 MPa, 300 MPa; time 1~9 min) were adopted to study the effect of different preprocessing ways on quality of hami melon. Futhermore, the effect of hardness maintenance in different concentrations of CaCl2 solution was evaluated. The polyphenol oxidase (PPO) and peroxidase (POD) activity of hami melon extract was inhibited effectively by hot water blanching, while the hardness and vitamin C content decreased significantly with increasing temperature and time of blanching. High pressure processing at 100~300 MPa could barely suppress PPO and POD activity of hami melon, and under certain conditions the enzyme activity was even activated, meanwhile the texture was seriously damaged. Vitamin C content also decreased significantly. However, 100℃ steam blanching inhibited PPO and POD activity effectively and also performed better than hot water blanching and high pressure processing in keeping hami melon texture and vitamin C. Therefore, 100℃ steam blanching at 1 min was chosen to preprocess hami melon, and in this condition PPO and POD residual activity levels were 55.5% and 46.0% respectively. Compared with the fresh hami melon, hardness maintained 80% and vitamin C lost only 13%. On this basis, soaking in 1.0% (m/m) CaCl2 solution improved hami melon hardness and vitamin C content by 7.6% and 6.8%, respectively.
