High-pressure-freezing effects on textural quality of carrots

Raw or 3 min blanched carrots were pressurized for 45 min at -18 degrees C similar to -20 degrees C and then thawed at 20 degrees C. When carrots were frozen at 100MPa (ice I), firmness decreased and strain increased. Textural values of carrots pressurized at 200MPa (liquid), 340MPa (ice III), 400MPa (ice V) at ca. -20 degrees C were acceptable. When pressure was increased above 500MPa, the strain increased. Release of pectin and histological damage in carrots pressurized at 200, 340 and 400MPa were less than carrots frozen at 100 and 700MPa (ice VI). After pressurization at 200 and 340MPa at -20 degrees C, carrots were stored in a freezer (-30 degrees C). Firmness decreased and strain increased, but textural values were higher and histological structure were more intact than those frozen at -30 degrees C (0.1MPa) then stored. Thus, high-pressure-freezing at 200, 340 and 400MPa appeared to be effective in improving both the texture and histological structure of frozen carrots.