The speed of sound and the acoustic reflection coefficient of sucrose (0 to 60 wt%), glycerol (0 to 50 wt%), sodium chloride (0 to 27 wt%) solutions and tomato ketchup (0 to 100 wt%) dispersions were measured using a modified pulse-echo technique (2.25 MHz transducer, 20 Њ Њ Њ Њ ЊC). The density of all solutions is measured using a vibrating tube densitometer. All measured parameters are linear functions of concentration. Ultrasonic reflectance can provide equally precise measurements of concentration as conventional ultrasonic velocity measurements. For all samples except concentrated ketchup (Ͼ Ͼ Ͼ Ͼ Ͼ 50 wt%), measured reflectance is demonstrated to be a function of ultrasonic velocity and density.

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Dispersions of coating fat in corn oil (2.5-12.5 wt%) were prepared following two different protocols: Type A dispersions had an average crystal size of 30-36 µm, whereas type B dispersions were less than 1 µm. In both dispersions the fat crystals were aggregated into larger structures (up to 80 µm). The longitudinal ultrasonic properties (i.e., velocity, attenuation, and reflectance) were linearly related to the solid fat content, but only attenuation was sensitive to the different microstructures. The velocity and reflectance measurements were modeled using the Urick equation. Shear ultrasonic reflectance and oscillatory viscometry were used to measure the dynamic viscosity of all dispersions. According to both methods, type B samples were always more viscous than type A at a similar solids content. The correlation between the two techniques was good (r 2 > 0.99), but the numeric agreement was different for both systems.