A study of palmitic-stearic triglycerides and their binary mixtures by differential thermal analysis (DTA) - I - pure triglycerides

Perron, Roger; Petit, J; Meynier, André

doi:10.1016/0009-3084(69)90025-5

Cited by 22 publications

(6 citation statements)

References 42 publications

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“…Despite the same cooling rate, the crystallization occurred at different temperatures, resulting in different solid states. The solid phase that solidifies at 334 K exhibits only one endothermic peak on the scanning pattern, indicating that tristearin crystallized in the β-form upon slow cooling of the melt, as also concluded by Perron et al 29 However, the crystalliza-tion occurred also at 329 K under the same cooling rate and the formed solid consisted of more than one polymorph. The scanning pattern of this solid phase (curve 3, Figure 1) demonstrates three endothermic effects, where the newly identified peak at 337.5 K corresponds to the melting of one of the β′-polymorphs.…”

Section: (B) Influence Of the Cooling Ratesupporting

confidence: 75%

“…Although crystallized at different cooling rates, the R-phase always crystallized in the vicinity of 326.6 K. The onset of melting of the R-phase (327 K) coincides with this value, meaning that no significant undercooling is needed for the nucleation of the R-form. The absence of undercooling for the R-phase has already been discussed, 24,29 while it is also observed during measurements in the adiabatic calorimeter (Figure 8, curve 1).…”

Section: (B) Influence Of the Cooling Ratesupporting

confidence: 73%

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Thermal Properties of Tristearin by Adiabatic and Differential Scanning Calorimetry

Matovic¹,

Miltenburg²,

Los

et al. 2005

J. Chem. Eng. Data

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The thermal behavior of tristearin was studied by adiabatic calorimetry and differential scanning calorimetry (DSC). Specific heat capacities of two polymorphic forms were measured in the adiabatic calorimeter, where the -form was measured from 10 K to 370 K and the R-form was measured from 175 K to 370 K. The start of the measurement of the stable -form from 10 K allowed the calculation of its entropy, so we report the derived values of absolute entropy for the two forms of tristearin at 298.15 K. The enthalpies of fusion and melting temperatures for each polymorph were calculated from both the adiabatic and the DSC experimental data and are compared to the literature values. The values for the enthalpies of fusion of the stable -form are in excellent agreement, being (221.6 ( 1) J‚g -1 and (219.6 ( 2) J‚g -1 according to the adiabatic and DSC measurements, respectively. The data for the R-form are not in so good agreement, which we attribute to the difficulty to crystallize this phase in its pure form. Moreover, we examined the fleeting existence of the ′-form and its transformation to the -phase under isothermal conditions. IntroductionGlycerides form an important class of natural products, as they are constituents of oils and fats. A very detailed review of the thermal properties of the acylglycerides is found in the chapter written by Hagemann in the Surfactant Science Series. 1 Glycerol trioctadecanoate (C 57 H 110 O 6 ), or tristearin for short, often indicated as SSS, is one of the saturated monoacid triglycerides and is probably the best researched triglyceride concerning thermal behavior. Despite this fact, we undertook this research as we feel that the combination of adiabatic calorimetry and DSC can give more precise data and a better insight in the crystallization processes. Moreover, the use of adiabatic calorimetry made it possible to start the measurements at such a low temperature that the absolute entropy of the stable phase could be calculated. Tristearin exhibits four polymorphic forms (R, 2 ′, 1 ′, and ), which have been identified by different techniques, like X-ray studies, 2-12 DSC, 7-18 Raman spectroscopy, 11 calorimetry, 20-22 and microscopy. 23 In this work, we observed the existence of two ′-forms by DSC, but the small temperature range in which the 2 ′-phase occurred prevented detailed measurements on this form. In previous publications, we reported on the thermal properties of trielaidin 25 (or EEE) and tripalmitin 26 (or PPP). This work is part of a research project aimed at the study of metastable crystallization of binary mixtures, tristearin being one of the possible constituents.

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Section: (B) Influence Of the Cooling Ratesupporting

confidence: 75%

Section: (B) Influence Of the Cooling Ratesupporting

confidence: 73%

Thermal Properties of Tristearin by Adiabatic and Differential Scanning Calorimetry

Matovic¹,

Miltenburg²,

Los

et al. 2005

J. Chem. Eng. Data

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“…It is interesting to compare these curves to the "cryothermograms" of Perron et al (29), who analyzed various triglyc- 22 90 0 90…”

Section: Resultsmentioning

confidence: 99%

Modulated temperature differential scanning calorimetry for examination of tristearin polymorphism: I. Effect of operational parameters

Singh

Jalali

Aldén

1999

J Americ Oil Chem Soc

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The transformations of tristearin were examined by modulated temperature differential scanning calorimetry (MTDSC) in order to study the effect of operational parameters on the nature of information obtained from this technique. Tristearin has been used as a model polymorphic system showing metastable phases and complicated transformation routes occurring at relatively slow rates. The parameters examined were underlying heating/cooling rates and the amplitude of modulation. The first conclusion is that MTDSC enables overlapping α-melting and β-crystallization events to be separated, thus increasing the information obtained compared to normal thermal analysis. Other general conclusions are that observation of reversible processes is strongly influenced by the underlying heating rate; low to moderate heating rates are recommended. Amplitude of modulation has a complicated effect on the phenomenon being studied; when studying systems that exhibit metastable or polymorphic transitions, it is recommended that a range of amplitudes be tested to enable confirmation of whether an observed "recrystallization" effect is a new phase or the same phase as the one melting. Cooling with modulation disturbs the crystallization process, possibly leading to smaller or imperfect crystals; however, the phases obtained are not different compared to normal DSC. The usefulness of MTDSC in analyzing these types of complicated systems is primarily qualitative at the moment. Some recommendations have been made as to the combinations of parameters for studying such systems.Paper no. J8832 in JAOCS 76, 499-505 (April 1999) FIG. 1. Schematic of polymorphic phase transitions in saturated monoacid triglycerides. Dotted lines represent transitions that occur via special thermal treatments only.

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“…Therefore, thermal properties of fats and oil are closely related to those of TG that constitute the major part of the lipids. In addition, thermal behavior of a TG admixture is described by phase diagrams with phase temperature boundaries (29,30) and thermodynamic parameters (31). Figure 5 shows the comparative DSC thermograms of both genuine and randomized lard under a constant stream of N 2 (150 mL/min) and heating rate (10~ The thermogram of genuine lard is quite different from that of randomized lard, and these differences could be attributed to the different TG composition (Tables 2 and 3) that resulted from interesterification.…”

Section: Tg Compositional Analysesmentioning

confidence: 99%

Compositional and thermal characterization of genuine and randomized lard: A comparative study

Al‐Rashood

Abou‐Shaaban

Abdel-Moety

et al. 1996

J Americ Oil Chem Soc

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Composition and thermal characterization of genuine and randomized lard were investigated comparatively in an attempt to find common merits that assess lard detection. The investigation included compositional and positional distribution of fatty acids, triacylglycerol profiling by gas chromatography (GC) and reversed-phase high-performance liquid chromatography (RP-HPLC), as well as thermal behavior by differential scanning calorimetry (DSC) of both samples. Individual and total saturated and unsaturated fatty acid composition in total fats of both genuine and randomized lard were identical. On the other hand, the results of pancreatic lipolysis/GC analysis showed that the average percent palmitic acid [PAEF(%)] and myristic acid [MAEF(%)] enrichment factors of genuine (280 and 270) and randomized lard (I I 0 and 98) were quite different. Thus, application of PAEF to detect randomized lard is of no value. However, normalization of fatty acid distribution by randomization in 2-monoacylglycerols made the individual and total saturated and unsaturated fatty acids almost identical to that of total fat and neutral triacylglycerols (TG) of lard. TG compositional analysis by GC revealed that both genuine and randomized lard had six dominant TG (C46, C48, C50, Cs2 , Cs4, and C56) with quite different concentrations. TG with C52 represent the major constituent of genuine and randomized lard. TG profiling of samples was also carried out by RP-HPLC with a refractive index detector. The same peaks were eluted in both samples, but the area % of major peaks changed due to randomization. 2-Palmitooleostearin (SPO) was found in high proportion in lard. However, the ratios of SPO to 2-palmitooleolinolein of both genuine and randomized lard are close (0.6 • 0.05) and significantly distinguishable from that of beef (4.24), mutton (6.17), chicken (0.21), and turkey (0.14) fats. The DSC thermogram and thermodynamics of phase transitions of both samples were quite different and do not reveal common characteristic(s) that could be used for immediate detection of lard substances in fat admixtures.

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A study of palmitic-stearic triglycerides and their binary mixtures by differential thermal analysis (DTA) - I - pure triglycerides

Cited by 22 publications

References 42 publications

Thermal Properties of Tristearin by Adiabatic and Differential Scanning Calorimetry

Thermal Properties of Tristearin by Adiabatic and Differential Scanning Calorimetry

Modulated temperature differential scanning calorimetry for examination of tristearin polymorphism: I. Effect of operational parameters

Compositional and thermal characterization of genuine and randomized lard: A comparative study

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