Abstract:  The characteristics of moisture transfer in osmotic treatment of tilapia fillets were investigated in this study. The changes of weight were quantitatively determined during osmotic treatments of fresh tilapia fillets with the sodium chloride concentration (10%～30%), ratio of solid to liquid (1:5～1:15) and fillet thickness (3～10 mm) as the independent treatment factors. Results were as follows: First, the weights of fillets increased when fresh tilapia fillets were soaked in 10% sodium chloride (NaCl) solution. The osmotic dehydration of fillets occurred in 20% NaCl solution or more. Second, if the osmotic solution concentration and fillet thickness were set, the dehydration rate (DH) of fillets was found to increase with increase of ratio of solid to liquid, which means ratio of fillet weight to solution. Finally, effects of fillet thickness on DH were found to be related to osmotic time. The DH of thinner fillets could be reduced when treatment time was prolonged.

Key words: tilapia, fish fillet, osmotic treatment, moisture, transfer