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Texture and histological structure of carrots frozen at a programmed rate and thawed in an electrostatic field

Fuchigami, M., Hyakumoto, N., Miyazaki, K., Nomura, T., Sasaki, J.
Journal of food science 1994 v.59 no.6 pp. 1162-1167
carrots, texture, freezing, thawing, electrostatic interactions
To investigate the most suitable rate of freezing and method for thawing, raw and blanched carrots were frozen with LN2 (freezing rate: -5 degrees C or -2 degrees C/min, final temp: -30 degrees C) using a program freezer (PF), or were frozen using conventional freezers (F: -80 degrees C, -30 degrees C and -20 degrees C). Then, they were thawed in five different ways: electrostatic thawing (ET, -3 degrees C, 17 hr); -3 degrees C, 17 hr, 5 degrees C, 17 hr, 20 degrees C, 30 min; 100 degrees C, 3 min. Firmness of thawed carrots and amount of undamaged tissues by LM and TEM observations were greatest to least: PF -5 degrees C/min > PF -2 degrees C/min > -80 degrees CF > -30 degrees CF > -20 degrees CF, and ET greater than or equal to -3 degrees C > 5 degrees C > 20 degrees > 100 degrees C, respectively. Results suggest the optimum rate of freezing was -5 degrees C/min. The frozen disks were defrosted comparatively fast even at -3 degrees C by ET. Drip, cell damage and softening of disks were prevented by ET.