The speed of sound was measured in solutions of sucrose (0-70 wt/vol%), glycerol (10-30 wt/vol%) and orange juice (0-40 solids wt/vol%) as a function of temperature (10 degrees C to -13 degrees C). The velocity (c) in the unfrozen solutions, including the supercooled samples, could be modeled as a simple linear function of temperature (T, degrees C) and composition (x, wt/vol%): c = c(w) + k(x)x + k(T)T where c, is the speed of sound in water at 0 degrees C, and k(x) and k(T) are solute-dependant constants. There was a large increase in ultrasonic velocity corresponding to freezing in these samples (e.g., an unfrozen 10% sucrose solution has a speed of sound of 1416 in s(-1) at -5 degrees C while a similar frozen solution has a velocity of 1983 m s(-1)). The ice content was estimated from phase diagrams of similar samples and was a linear function of the change in ultrasonic velocity upon freezing for samples < 8 degrees C. Some details of the effects of ice microstructure and possible theoretical approaches to its effects on ultrasonic properties are also discussed. (c) 2006 Elsevier Ltd. All rights reserved.