Moroccan oil characterization

using pulse-echo ultrasonic technique

 

N. Aouzale*, A. Chitnalah, H. Jakjoud

Laboratoire des Systèmes Electriques et Télécommunications  L.S.E.T.

Université CADI AYYAD FST BP 549, 40000 Gueliz Marrakech-Maroc.

* Corresponding author. E-mail: aouzale_noureddine@yahoo.fr

Received: 09 April 2009; revised version accepted: 12 November 2009

 

Abstract

     The food industry is becoming increasingly aware of the importance of developing new analytical techniques to probe complex foodstuff structures and to monitor their properties on-line during processing operations. Ultrasound has a number of attributes that make it well suitable for both of these applications. Ultrasonic instrumentation can be fully automated and make rapid and precise measurements. Ultrasound is non-destructive, non-invasive and can easily be adapted to analyze optically opaque systems. Different frequencies can be utilized, so that structural features within the food can be examined at a range of wavelength.

     In this work measurements of ultrasound velocity and attenuation in Moroccan oils are made using a pulse-echo method. The experimental setup consists of a piezoelectric transducer functioning at a central frequency of 2.2MHz. Processing the received echo allows us to determine the celerity and the absorption losses coefficient of the fluid under investigation.

The method has been validated by measuring the acoustical parameters of distilled water and glycerol and afterwards used to determine the acoustical characteristics of some Moroccan oils including Argan oil, commercial cooking oil and olive oil. Studied parameters are density, acoustical impedance, celerity, absorption losses coefficient, the dynamic viscosity and the compressibility modulus.

 

Keywords: Ultrasound; Material characterization; Piezoelectric devices; Viscoelastic properties; Pulse-echo method.

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