NMR relaxation studies to explore the role of emulsifier in tristearin polymorphic transformation

Abstract

Proton magnetic resonance measurements were performed onα andβ polymorphs of tristearin crystals. T1 relaxation time was measured with the Bruker PC Minispec at 20 MHz and 37° on the pure triglyceride crystals and therefore on tristearin crystallized in the presence of different solid surfactants. A significant negative correlation for T1 values and different compositions ofα andβ polymorphs in a mechanical mixture was found. The shortening of T1 relaxation time of theβ form was found to be different for the various types of the added surfactants while they have no effect on the relaxation time of theα form. A model was proposed according to which the presence of additives, such as surfactants, generates vacancies within the crystal lattice of triglyceride and enhances the freedom of rotation of the fat molecule about the terminal carbon‐carbon bond.

Study of the State of Water and Oil in Frozen Emulsions Using Time Domain NMR

“…(Table 4). This T 1 value, corresponding to the solid phase of fat, is slightly smaller than the one obtained with pure triolein (240 ms); this difference could be due to a difference in the crystallization state of the fat in the presence of the emulsifier (31). It would induce a less compact state of solid fat.…”

Study of triacylglycerol polymorphs by nuclear magnetic resonance: effects of temperature and chain length on relaxation parameters

“…The current results are in agreement with previous studies performed with one or two TAs at a single temperature. [6,7,13,14] The present study demonstrated that a general dynamic behavior can be observed for TAs at low or high NMR field whatever the chain length and the temperature studied. The results obtained from the proton T 1 measurements displayed a minimum ratio of 1 : 10 between the α and the β forms for the TA family chosen.…”

“…[6] Others T 1 measurements have suggested that the mobility of the terminal methyl group of tristearin was more constrained in the β polymorph than in the α polymorph. [7] T 1 relaxation time measurements have also made it possible to the study of lipid crystallization in complex food systems. [11] TAs have also been investigated using high-field NMR spectrometry, and this has allowed the spectral assignment of tripalmitin and tristearin in the three polymorphic forms.…”

Polymorphism of sugars studied by time domain NMR

“…Azoury [10] obtained a correlation coefficient of −0.991 between the average T 1 of a mixture of tristearin and the percentage of the a form in a mixture of α and β forms. We wanted to verify that the quantitative aspect of distributions could be applied to mixtures over the whole range of percentages.…”

“…In contrast, the T 1 of the α form of tristearin (hexagonal form) has been measured at 250 ms, while that of the β form (triclinic form) is 1.7 s [10]. According to Azouri [10], Norton [11] was the fi rst to use the parameter T 1 to diffe re n t i ate poly m o rp h i c forms.…”