Begining of fish defrosting by using non-destructive ultrasonic technique

International audience; During the experiments carried out in the laboratory on the monitoring and study of fish thawing by ultrasonic technique. We had difficulties in detecting the begining of the thawing which is the main criterion of fish quality control. To correct the problem we use the singular value decomposition (s.v.d.) method which is a mathematical tool.This allowed us to show by the ultrasonic technique the thawing start for cod which is a fish that had an average fat content. The results were good with a central frequency transducer equal to 500 kHz. However for salmon which is a fish that had a high content of fat; and for centrals frequencies transducers above 500 kHz the observed results were not very good.