Effects of high hydrostatic pressure on physico-chemical and structural properties of two pumpkin species.

The effects of high pressure treatments (200, 400, 600 MPa for 5 min) and a thermal treatment (85 °C for 5 min) were evaluated on cubes of two pumpkin species (Cucurbita maxima L. var. Delica and Cucurbita moschata Duchesne var. Butternut) up to 2 months of refrigerated storage. Increasing the pressure, small parenchyma cells from the pumpkin tissue exhibited collapses and separations, especially for Butternut. This species showed a lower hardness than Delica at time 0. For both species, 400 MPa and thermal treatment were the most effective in the inactivation of pectinmethylesterase, which reactivated after 2 months, especially for Butternut. Colorimetric parameters decreased after all treatments. Antioxidant activity resulted affected by pressure, showing a significant increase during storage especially for the samples treated at 200 MPa after 2 months, comparable to the thermal treated ones. Among the tested treatments, 400 MPa may be considered as the best option for the quality retention during storage.