Global Small-Angle X-ray Scattering Data Analysis of Triacylglycerols in the Molten State (Part I)

Sadeghpour, Amin; Ladd-Parada, Marjorie; Vieira, Josélio; Povey, M. J. W.; Rappolt, Michael

doi:10.1021/acs.jpcb.8b06704

Cited by 18 publications

(18 citation statements)

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“…More specifically, from our NMRD analysis (Figure ), we consider that the increase of R 1 at very low frequencies is related to ODFs, similarly to what has been observed previously in nematic and smectic phases . These ODFs could be explained in the light of our newly proposed model of the structured clusters of molten TAGs . Briefly, TAGs are thought to assemble in clusters immersed in an isotropic medium of TAGs from which some molecules start interacting with the outer fatty acids, thus creating an additional layer, or shell, which increases in coverage as temperature decreases.…”

Section: Discussionsupporting

confidence: 79%

“…[22,43,44] These ODFs could be explained in the light of our newly proposed model of the structured clusters of molten TAGs. [33,37] Briefly, TAGs are thought to assemble in clusters immersed in an isotropic medium of TAGs from which some molecules start interacting with the outer fatty acids, thus creating an additional layer, or shell, which increases in coverage as temperature decreases. These clusters might begin to orientate once a crystallisation-inducing temperature (such as 22°C) is reached, generating some of the first lamellar structures.…”

Section: Discussionmentioning

confidence: 99%

“…The amount of material in the fluid state is proportional to the diffuse scattering contribution centred at q = 2.55 nm −1 in the SAXS regime . Thus, to determine the fraction of material in the molten state, we determined the intensity (area under the curve), I liquid , of this scattering contribution from 1.8 to 3.2 nm −1 for all scattering patterns (see Figure ) and normalised this data by setting the first I liquid to unity.…”

Section: Methodsmentioning

confidence: 99%

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Early stages of fat crystallisation evaluated by low‐field NMR and small‐angle X‐ray scattering

Ladd-Parada

Povey

Vieira

et al. 2019

Magnetic Reson in Chemistry

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Low‐field time‐domain nuclear magnetic resonance (NMR; 20 MHz) is commonly used in the studies of fats in the form of solid fat content (SFC) measurements. However, it has the disadvantage of low sensitivity to small amounts of crystalline material (0.5%), thus often incorrectly determining crystallisation induction times. From spin–lattice relaxation rate measurements (R1) during the isothermal crystallisation measurements of cocoa butter between 0.01 and 10 MHz using fast field cycling NMR, we learnt previously that the most sensitive frequency region is below 1 MHz. Thus, we focused on analysing our 10‐kHz data in detail, by observing the time dependence of R1 and comparing it with standard SFCNMR and SFC determinations from small‐angle X‐ray scattering (SFCSAXS). Although not reflecting directly the SFC, the R1 at this low frequency is very sensitive to changes in molecular aggregation and hence potentially serving as an alternative for determination of crystallisation induction times. Alongside R1, we also show that SFCSAXS is more sensitive to early stages of crystallisation, that is, standard SFCNMR determinations become more relevant when crystal growth starts to dominate the crystallisation process but fail to pick up earlier crystallisation steps. This paper thus demonstrates the potential of studying triacylglycerols at frequencies below 1 MHz for obtaining further understanding of the early crystallisation stages of fats and presents an alternative and complementary method to estimate SFC by SAXS.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Early stages of fat crystallisation evaluated by low‐field NMR and small‐angle X‐ray scattering

Ladd-Parada

Povey

Vieira

et al. 2019

Magnetic Reson in Chemistry

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“…Those papers addressed questions regarding the role played by polymer selfand mutual-entanglement in the kinetics of memory effects.Recently, TAG crystallization has been studied [15][16][17][18]. Coexistence of solid and liquid state TAGs were reported [16]. The second paper [11] is especially interesting because it showed that the power law behavior of the overall crystal growth rate, found previously to be different for melts with and without memory, and interpreted in terms of changes in the structure and/or the dynamics of the entangled melt states, was not found in their NMR results.…”

Section: Introductionmentioning

confidence: 99%

“…This phenomenon has been studied for linear polymers [10][11][12], as well as for cocoa butter [13] and fatty acids [14]. Those papers addressed questions regarding the role played by polymer selfand mutual-entanglement in the kinetics of memory effects.Recently, TAG crystallization has been studied [15][16][17][18]. Coexistence of solid and liquid state TAGs were reported [16].…”

Section: Introductionmentioning

confidence: 99%

Crystal Memory near Discontinuous Triacylglycerol Phase Transitions: Models, Metastable Regimes, and Critical Points

et al. 2020

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It is proposed that “crystal memory”, observed in a discontinuous solid-liquid phase transition of saturated triacylglycerol (TAG) molecules, is due to the coexistence of solid TAG crystalline phases and a liquid TAG phase, in a superheated metastable regime. Such a coexistence has been detected. Solid crystals can act as heterogeneous nuclei onto which molecules can condense as the temperature is lowered. We outlined a mathematical model, with a single phase transition, that shows how the time-temperature observations can be explained, makes predictions, and relates them to recent experimental data. A modified Vogel-Fulcher-Tammann (VFT) equation is used to predict time-temperature relations for the observation of “crystal memory” and to show boundaries beyond which “crystal memory” is not observed. A plot of the lifetime of a metastable state versus temperature, using the modified VFT equation, agrees with recent time-temperature data. The model can be falsified through its predictions: the model possesses a critical point and we outline a procedure describing how it could be observed by changing the hydrocarbon chain length. We make predictions about how thermodynamic functions will change as the critical point is reached and as the system enters a crossover regime. The model predicts that the phenomenon of “crystal memory” will not be observed unless the system is cooled from a superheated metastable regime associated with a discontinuous phase transition.

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Bioinspired Oleic Acid–Triolein Emulsions for Functional Material Design

Freire

Haenni

Hong

et al. 2022

Adv Materials Inter

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Being amphiphilic lipids, these digestion products can selfassemble into a variety of lamellar and non-lamellar lyotropic liquid crystalline structures attractive for drug and nutrient delivery applications. [9] The dynamic composition of the lipolysis products during triglyceride digestion has a profound influence on the physicochemical properties of the colloidal structures. For example, surface-active lipolysis products can alter the interface of the emulsion particles and transfer water into the triglycerideoil phase. [10] They can further regulate the digestion process by competing with the lipase for the oil-water interface. [11] Their adsorption to the oil-water interface modifies the interfacial tension which, together with shear forces in the digestive tract, can further reduce the emulsion droplet size. The resulting increase in surface area for lipases to access their substrate can ultimately increase the digestion kinetics. Therefore, understanding the structure and properties of these biologically important systems contributes to the development of smarter food materials, which are of great interest for the food industry. [12] In addition to compositional changes, food colloids are also exposed to varying pH and ionic strength conditions as they travel along the digestive tract. While pH in the stomach can be very acidic, intestinal pH can reach alkaline pH values, with this broad pH range being one of the challenges of oral delivery of nutrients and drugs. [13,14] Such changes in the local microenvironment influence the ionization state of the carboxyl group of fatty acids. This modifies their solubility in aqueous media or in the hydrophobic interiors of the emulsion droplet, changing its interfacial properties and their potential to self-assemble into nanostructures. [15][16][17][18][19] The ionization state of acids at a given pH, however, is not exclusively dependent on their molecular structure. While the pK a of an isolated carboxyl group of monomeric fatty acid in water is 4.75, [20] different values are reported in literature for the apparent pK a of acids in self-assembled systems, strongly affected by a variety of parameters such as intermolecular interactions, presence of neighboring charges, dielectric constant, and ionic strength. [16,19,21,22] Therefore, these external parameters can indirectly affect the physicochemical properties of dispersions containing molecules that can be deprotonated. For the case of oleic acid (OA) in particular, reported values of apparent pK a at different conditions and environments range from 6.1 to 9.4. [16,19,23,24] Stimuli-responsive nanostructured emulsions can be utilized to innovate tailor-made materials in fields including biotechnology and food materials. This study reports the composition and pH-responsive colloidal and interfacial properties of the naturally abundant oleic acid-triolein-water emulsions, and applies the knowledge to the sustainable design of nanoemulsions. Small angle X-ray scattering, spinning drop tensiometry, multi-angle dynami...

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Global Small-Angle X-ray Scattering Data Analysis of Triacylglycerols in the Molten State (Part I)

Cited by 18 publications

References 100 publications

Early stages of fat crystallisation evaluated by low‐field NMR and small‐angle X‐ray scattering

Early stages of fat crystallisation evaluated by low‐field NMR and small‐angle X‐ray scattering

Crystal Memory near Discontinuous Triacylglycerol Phase Transitions: Models, Metastable Regimes, and Critical Points

Bioinspired Oleic Acid–Triolein Emulsions for Functional Material Design

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