High-pressure-freezing effects on textural quality of Chinese cabbage

Differences in texture and histological structure of Chinese cabbage (midribs) pressurized at room temperature or ca. -20 degrees C were investigated. Use of rising pressure at room temperature enhanced de-esterification of pectin in midribs and increased firmness and rupture strain. When samples were frozen at 100 MPa (ice I formed) and at 700 MPa (ice VI), rupture strain increased. However, texture of samples frozen at 200 MPa (liquid), 340 MPa (ice III), 400 MPa (ice V) was comparatively intact. Release of pectin and histological damage in midribs frozen at 200 and 340 MPa were less than midribs frozen at 100 and 700 MPa, High-pressure-freezing was more effective in improving both texture and histological structure than freezing (-30 degrees C) at atmospheric pressure. However, texture of high pressure-frozen midribs (pliant) was greatly different from raw midribs (crisp).