Effect of low frequency ultrasound thawing method on the quality characteristics of Peru squid ( Dosidicus gigas).

The effects of different thawing methods (air thawing, water soak thawing, refrigeration thawing, low frequency ultrasound thawing at 160, 240, 320 and 400 W) on thawing time, thawing loss, cooking loss, water-holding capacity and texture of frozen squid were investigated. The results showed that thawing loss and thawing time were reduced significantly ( p < 0.05) by ultrasound thawing compared with the water soak thawing and air thawing, but the cooking loss had no significant difference ( p > 0.05). Results of the ultrasound thawing especially at 160 and 240 W on microstructure showed less destructive effect on muscle. The microstructure of the muscle was destroyed significantly after air thawing and water soak thawing compared with the ultrasound thawing, which showed that more fibre structure was broken and the gap between the muscle fibres was increased significantly. Low-field NMR results showed that the ability of immobile water shifting to free water after ultrasound thawing was lower than air thawing and water soak thawing, which was consistent with the results of thawing loss and cooking loss. Ultrasound thawing might be chosen as an alternative method to enhance the quality during thawing process.