Time resolved x-ray diffraction studies of the polymorphic behaviour of tripalmitin using synchrotron radiation

Kellens, Marc; Meeussen, Wouter; Riekel, Christian; Reynaers, Harry

doi:10.1016/0009-3084(90)90153-i

Cited by 79 publications

(54 citation statements)

References 12 publications

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“…The discrepancy in the ratio is attributable either to the broadening of the two 3L peaks and their overlapping with the main 2L peak or to the existence of more species (see below). The asymmetry observed for the main 2L peak of AMF is in favor of the latter hypothesis [10]. On the other hand, in the present experimental conditions it was not possible to make a univocal attribution of these four sub-cells identified at wide angles to the two varieties observed at small angles.…”

Section: Polymorphic Evolution During Conditioning Of Milk Fat At 4 O Ccontrasting

confidence: 82%

Crystalline structures formed in cream and anhydrous milk fat at 4 °C

Lopez

Bourgaux

Lesieur

et al. 2002

Lait

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-Crystallization and polymorphic evolutions of triacylglycerols (TG), at 4 o C, in cream and anhydrous milk fat (AMF) samples were studied using high-sensitivity differential scanning calorimetry (DSC), time-resolved synchrotron X-ray diffraction (XRD) and density measurement, and compared as a function of time after quenching from 60 to 4 o C. The evolution of the two crystalline structures initially formed in both samples, corresponding to a metastable 2L (47 Å) and a 3L (70.5 Å) lamellar organization with hexagonal chain packings (α form), were monitored in isothermal conditions at 4 o C as a function of time t. For t > 15 min, short spacings showed the formation of a β' packing of the chains in coexistence with the α form. In AMF, the occurrence of some β form was also recorded. For long spacings, a 2L (39 Å) structure was formed in cream with the 3L (70.5 Å) structure still being preponderant after conditioning for 30 min at 4 o C. In AMF samples, a TG polymorphic transition 3L (70.5 Å) → 2L (39 Å) + 3L (66 Å), correlated with an exothermic peak recorded simultaneously by DSC, was clearly visible. At t > 100 h conditioning at 4 o C, the same crystalline structures were found in cream and AMF with the coexistence of at least a 2L (40.5 Å) and a 3L (54.2 Å) longitudinal organization, associated with α, β' 2 , β' 1 and β packings of the chains. The melting behaviors of cream and AMF were monitored on heating at 2 o C . min -1 by coupled XRD as a function of temperature and DSC experiments. The absence of further structural evolution and polymorphic transition until final melting demonstrates the relative stability of the structure formed. The evolution of cream density after quenching to 4 o C revealed two transitions, the amplitudes, rates and duration of which coincided with DSC and XRD experiments. All data are in agreement in demonstrating that two transitions, a fast and a slow one, occur in dairy products after fast cooling to 4 o C. Cristallisation / polymorphisme / triacylglycérol / diffraction des rayons X / calorimétrie

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Section: Polymorphic Evolution During Conditioning Of Milk Fat At 4 O Ccontrasting

confidence: 82%

Crystalline structures formed in cream and anhydrous milk fat at 4 °C

Lopez

Bourgaux

Lesieur

et al. 2002

Lait

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“…The PPP content increased significantly in all SFs vs. PS (p < 0.05) due to PPP's high-melting point (45°C, 56°C, and 66°C for α, β′, and β forms, respectively). [29] , This led to the crystallization of PPP at all three temperatures during fractionation. The increase in trisaturated TAGs with long-chain fatty acids in SF from that of the original fat after fractionation has been observed in previous reports on PS [5] and coconut fat.…”

Section: Chemical Characterizationmentioning

confidence: 99%

Composition and crystallization behavior of solvent-fractionated palm stearin

Podchong

Tan

Sonwai

et al. 2018

International Journal of Food Properties

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Palm stearin (PS) is an extensively used trans-free hardstock. Depending on process parameters, fractions with unique compositions, hardness, and solid fat content can be tailored toward specific applications. In this work, the composition and crystallization of PS fractionated with acetone at 30°C, 35°C, or 40°C into various liquid (LF) and solid (SF) fractions were investigated. After fractionation, iodine value (IV) of PS changed from 37 to values ranging from 24 to 51. The IV of the LF increased with a decrease in fractionation temperature whereas that of the SF (~24) was unaffected. The main fatty acids of all PS fractions were palmitic and oleic acids, with the LF having a lower palmitic acid but higher oleic acid content than the SF. LF and SF obtained at higher fractionation temperatures showed more rapid crystallization rates. Under the microscope, the LF fractionated at 30°C and 35°C consisted of spherulites whereas those fractionated at 40°C exhibited dendritic crystals. All SF consisted of spherulites comprised of large rod-like crystals. All samples existed as mixtures of β' and β crystals. This study serves as the basis for the development of baking margarines and pastry shortenings using fractionated PS.

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“…XRD complements DSC for elucidating polymorphism of pure TG and fats. The coupling of XRD as a function of temperature (XRDT) and DSC was used to characterize the structural and thermal behaviors of pure TG [43,44], fats [30, 32-34, 36, 37, 44, 45] and dispersed systems such as natural bovine milk fat globules [29,31,34,36] and dromedary milk fat globules [46]. Camel milk fat is mainly composed by TG with a broad variety of FA composition.…”

Section: Polymorphismmentioning

confidence: 99%