Abstract:The grass carp salting was treated with ultrasound to reduce the salting and drying time. The effects of ultrasound treatment on the saline temperature , moisture content, salinity, texture, microstructure and sensory evaluation of dried grass crap were investigated after salting treatment assisted with different ultrasound power (0 W, 120 W, 240 W, 360 W and 480 W) at 40 kHz and then dried with low temperature heat pump operated at 20 ℃ with 50% humidity. Results showed that the ultrasound had an obvious heat effect. Compared to the ambient temperature, the temperature of saline could be increased by 4~16 ℃with ultrasound treatment (180 min) in an open salted container. The salinity, elasticity and sensory scores increased from 3.58%, 0.70 g, 29.00 to 5.21%, 0.84 g and 43.00, respectively, after treated with ultrasound-assisted salting 120 min and then dried with heat pump for 50 h, and the moisture content and hardness decreased from 27.04% and 2355 N to 24.88% and 1582 N, respectively. Results of paraffin sections and scanning electron microscopy showed that the ultrasound-assisted salting treatment completely destroyed the connective tissues among the muscle fibers, and a quick salt could enter into the muscle fiber cells, which made muscle tissues more full. Consequently, ultrasound-assisted salting could accelerate the rates of salting and drying of grass crap, which improved the quality of dried grass crap product.
