Physical Properties of Triglycerides III: Ultrasonic Sound Velocity

Abstract

The ultrasonic sound velocity has been measured at 2WC and at 4OoC for a number of triglycerides in the liquid state. From these data we have computed molar sound velocities according to Rao. Using published data on fatty acid methyl esters and a previously derived relation for triglycerides, an equation is given which relates the ultrasonic sound velocity of a mixture of triglycerides to its refractive index, density, and iodine value. The applicability of this relation to fatty oils is checked against a number of original fatty oils.Physikalische Eigenschaften der Triglyceride 111: Ultraschall-Geschwindigkeit Bei einigen fliissigen Triglyceriden wurde die Ultraschall-Geschwindigkeit bei 200 und 4OoC ermittelt. Aus diesen Werten wurden die molaren Schallgeschwindigkeiten nach Rao berechnet. Mit Hilfe der bereits bekannten, bei Fettsaure-methylestern gewonnenen Daten und einer friiher abgeleiteten Beziehung fur Triglyceride wurde eine Gleidmng aufgestellt, die die Beziehungen zwischen der Ultrascfiall-Geschwindigkeit eines Gemisches von Triglyceriden und dem Brechungsindex, der Dichte und der Jod- I n t r o d u c t i o nThe field of ultrasonics is comparatively new. Many techniques, based on the knowledge of the velocity of sound in a compound have, however, already found wide-spread application. The sound velocity in ;L compound is closely related to many physical properties of the medium and knowledge of this magnitude has expediently been applied to the evaluation of otherwise more inaccessible values. Reviews on the applicability of ultrasonics to chemical and physical problems have been presented by T. W. Ridzards et all, L. Berginann 2, W. Schaaffs and many others.The velocity of a wave due to longitudinal vibrations in a liquid medium is expressed as: the propagation taking place adiabatically and independent of the frequency. In this equation u is the sound velocity, pad and pis are the adiabatic and the isothermal compressibilities of the liquid respectively and d is the density. K is the ratio of the specific heats at constant pressure and a t constant volume (=C,/C,), which is also equal to piS/pad.The derivation of the adiabatic compressibility is one of the major applications of ultrasonics in the field of thermodynamics. Another application is the derivation of C,, the specific heat at constant pressure. We then make use of the following expression:where a is the coefficient of thermal expansion and T is the absolute temperature. The isothermal compressibility can be obtained from relatively simple measure-* Present address: Chevron Research Comp., Richmond, Calif. USA 94 802.

Topographical Distribution of Lipids Inside the Mandibular Fat Bodies of Odontocetes: Remarkable Complexity and Consistency

“…This revelation permits the first detailed consideration of these specialized fat depots from a functional perspective. Empirical inverse relationships between carbon chain length and sound speed [46], [47] mean that acoustic waves will move faster through longer lipids than through shorter ones. In the mandibular fat bodies of all odontocetes we examined, the shortest FA present in each head were concentrated in the center of the inner fat body and immediately adjacent to the earbones.…”

“…Although our understanding of odontocete sound reception is limited, we know that the acoustic properties of organic compounds vary with chemical structure [46], [47], and that there will be an inherent variation in sound transmission through the fat bodies constructed from different materials. Thus, by nature of their mandibular lipids, odontocetes from certain families may receive and perceive sounds differently than those from others.…”

Solid fat content determination by ultrasonic velocimetry

“…The ultrasonic velocity of liquid oils has been correlated to the average molecular structure of the fatty acids present (e.g., chain length and degree of unsaturation), hence, ultrasonic velocimetry has been proposed as a means of assessing the origin or quality of edible oils (Gouw & Vlugter, 1964, 1966, 1967Javanaud & Rahalkha, 1988;McClements & Povey, 1988a;Rao, Reddy, & Prabhu, 1980;Singh & Singh, 1980). The ultrasonic absorption spectra of liquid oils depend on their high frequency shear and compression rheology (Gladwell, Javanaud, Peters, & Rahalkar, 1986;Grigor'ev, Manucharov, Mikhailov, & Khakimov, 1976).…”

Nitrogen solubility in odontocete blubber and mandibular fats in relation to lipid composition

“…Regardless of dominant lipids, there appears to be a common topographical distribution in acoustic fats; WEs and shorter chain components are concentrated in the center of the tissue, surrounded by TAGs and longer chain components . As sound speed decreases through lipids with shorter chains and higher WE content (Gouw and Vlugter, 1967;Varanasi et al, 1975), this arrangement likely focuses outgoing and incoming sound Blomberg and Jensen, 1976;Blomberg and Lindholm, 1976;Koopman et al, 2006), although the specific mechanisms and pathways have not yet been established.…”