Effect of Physical Osmosis Methods on Quality of Tilapia Fillets Processed by Heat Pump Drying

In order to achieve the influence of different pretreatment methods on heat pump dried tilapia fillets, the effects of trehalose, ultrasound-assisted and freeze-thaw cycle assisted osmotic dehydration on the color, rehydration, texture and Ca2+-ATPase activity were investigated. Tilapia fillets (100 mm length x 50 mm width x 5 mm height) were first osmoconcentrated in a trehalose solution combined with 4 degrees C under atmospheric pressure for 1 h, different power of ultrasound and freeze-thawing respectively, then heat pump dried. The results showed that under the same drying method, the comprehensive score of ultrasound in 400 Watt was best, compared to freeze-thaw, the ultrasound pretreatment had a significant (p<0.05) effect on the color and Ca2+-ATPase activity, but had no significant (p>0.05) effect on the rehydration and texture. However, both of them significantly (p<0.05) affected the quality in comparison to that of osmosis at 4 degrees C. It indicates that suitable ultrasonic pretreatment conditions improve the quality of dried products effectively and the conclusion of this research provides reference for heat pump dried similar products.