Effect of ultrasonic and osmotic dehydration pre-treatments on the colour of freeze dried strawberries.

The effect of pre-treatments on the colour of freeze-dried strawberries was studied. Strawberries were subjected to different ultrasound and osmotic dehydration conditions followed by freeze-drying. Two concentration levels of sucrose solution (25 and 50 % w/w) and four levels of processing time (from 10 min to 45 min) were studied.