Ultrasonic-assisted flowing water thawing of frozen beef with different frequency modes: Effects on thawing efficiency, quality characteristics and microstructure

[Display omitted] •Ultrasonic-assisted thawing significantly reduced the thawing time of frozen beef.•Product quality was improved by 22 and 22/33 kHz of ultrasonic-assisted thawing.•Frozen beef thawed by these frequency modes can retain more immobilized water.•These frequency modes thawed frozen beef maintained the myofibril structure better. This study aimed to evaluate the effects of ultrasonic-assisted thawing at different frequency modes (mono-, dual- and tri-frequency) on the thawing efficiency and quality evaluation of frozen beef. The thawing time, muscle quality, and microstructure of frozen beef were studied. The results showed that ultrasonic-assisted thawing effectively reduced the thawing time by 15.7–45.4% compared with flowing water thawing. For the quality properties of beef tissue, the ultrasound-assisted thawing with the single-frequency of 22 kHz and the dual-frequency of 22/33 kHz showed a higher water holding capacity; meanwhile, shear force values were also significantly decreased, and the tenderness of beef tissue was improved accordingly under such conditions. The microstructure analysis showed that the distribution of beef muscle fibers became closer and more regular. Therefore, ultrasound-assisted thawing treatments at 22 kHz single-frequency and 22/33 kHz dual-frequency have a high potential application value in the thawing industry of frozen beef.