The performance of unhydrogenated soybean oil (USBO) and partially hydrogenated soybean oil (PHSBO) was evaluated by comparing their frying stability. Ultrasonic velocity was used to evaluate the oils. Measurements of free fatty acids (FFA) and total polar compounds (TPC) are typical indexes of oil degradation. Oils were heated at 180 °C for periods of 8 h per day for 4 consecutive days. The results from the ultrasonic analyses show different influences of thermo-oxidation on USBO and PHSBO. The ultrasonic measurements had strong correlations with chemical changes. Consequently, the ultrasonic method is useful to obtain information on the quality of the used frying oils.<br><br>La eficacia de aceites de soja sin hidrogenar (USBO) y aceites de soja parcialmente hidrogenado (PHSBO) fue evaluada por comparación de sus estabilidades de fritura. La velocidad ultrasónica fue usada para evaluar los aceites. La medida de ácidos grasos libres (FFA) y compuestos polares (TPC) son típicos índices de degradación de aceites. Los aceites fueron calentados a 180 °C en periodos de 8 h por día durante 4 días consecutivos. Los resultados del análisis ultrasónico muestran diferentes influencias de termooxidación en USBO y PHSBO. Las medidas ultrasónicas tuvieron una fuerte correlación con cambios químicos. Consecuentemente, el método ultrasónico es útil para obtener información en la calidad de aceites de fritura usados

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In this present work, our objective is to study the feasibility of the control of the maturity of orange fruit by the ultrasonic echo pulse method with immersion in water. This study relates to two varieties of orange (Navel and Mandarin) which are the most harvested particularly in the region of Souss-Massa-Drāa in Morocco. Contrary to the works already published in this field, we worked in the high frequencies by the means of a focusing transducer with 20MHz as a central frequency. By taking into account the strong attenuation of the ultrasounds in the texture of fruits and vegetables, we limited our study only to the characterization of the external layer called the flavedo characterized by its very small thickness. The use of the high frequencies will allow us a characterization of high resolution of the orange peel with a high space resolution. This control is based mainly on the measure of the ultrasonic parameters eventually velocity and attenuation in order to check the aptitude of this ultrasonic method to detect the degree of maturity of the fruit without passing by penetrometric and biochemical measurements which are mostly correlated with human perception concerning the firmness of the fruit but they are generally destructives.

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The nondestructive investigation by ultrasound has become a fundamental tool for characterizing rocks. We applied this technique for characterizing samples of rocks. The later had been members of the following three big families of geogical classification: magmatic rocks, metamorphic rocks, sedimentary rocks. The method usually used is based on the measurement of ultrasound parameters, <i>i.e.</i> the longitudinal and transversal propagation velocities. The measurement of these parameters allows to determine the mechanical properties of each rock. These studies do not allow to find the three big axes of the rocks. In this work we show for each rock his corresponding ultrasonic signature by the use of his experimentally determined Lamb dispersion curves. The obtained results put in evidence that the descending slope of the Lamb modes is a reliable and efficient criterion for classifying rocks by ultrasound. This is an adequate solution for a good classification of rocks. It gives a high precision, it is reliable and quick and last not least cheap