In situ monitoring of solid fat content by means of pulsed nuclear magnetic resonance spectrometry and ultrasonics

MARTINI, BERTOLI, HERRERA, NEESON, MARANGONI

JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY (JAOCS)

AOCS Press

Lugar: Champaign, USA; Año: 2005 vol. 82 p. 305 - 312

0003-021X

An ultrasonic technique was developed to study the crystallization process of edible fats on-line. A chirp wave was used instead of the conventional pulser signal, thus achieving a higher signal-to-noise ratio. This enabled measurements to be made in concentrated systems (20% solid fat content (SFC)) through a 8.11 – cm thick sample without significant signal loss. Fat samples were crystallized at 20, 25, and 30°C at a constant agitation rate of 400 rpm for 90 min. The crystallization process was followed by ultrasonic spectroscopy and a low-resolution pulsed nuclear magnetic resonance spectrometer. Specific relationships were found between ultrasonic parameters (integrated response, time of flight (TF), and full width half maximum) and SFC. TF, which is an indirect measurement of the ultrasonic velocity (v), was highly correlated to SFC (r2 > 0.9) in a linear fashion (v = 2.601 SFC + 1433.0).