TEXTURE AND HISTOLOGICAL STRUCTURE OF CARROTS FROZEN AT A PROGRAMMED RATE AND THAWED IN AN ELECTROSTATIC-FIELD

To investigate the most suitable rate of freezing and method for thawing, raw and blanched carrots were frozen with LN(2) (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>-2O degrees CF, and ET greater than or equal to-3 degrees C>5 degrees C>20 degrees C> 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.