Abstract: Ultrasonic analysis is based on the relationship between ultrasonic parameters (attenuation and velocity) and the contents of components to reach an analyzed solution. This relationship is significantly affected by the solution temperature. In this paper, ultrasonic velocity and attenuation were studied as a function of temperature and contents of main components (fat and protein) in milk. The experimental results showed that the ultrasonic velocity in milk increases and then decreases at 30～ 50℃. However, the attenuation increases with rising temperature. At the same temperature, both the velocity and the attenua- tion make changes negligibly. According to the experimental results, the contents of main components as functions of velocity and attenuation are computed. This study can be used to improve the assay method and system for milk.

Key words: velocity, attenuation, temperature, fat, protein