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Abstract  

The crystallisation properties of a mixture of triacylglycerols (TG), cocoa butter (CB) 75%/miglyol 25%, were investigated on cooling at 0.5 °C/min using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The influence of (i) the dispersion of TG within nanoparticles stabilised by proteins, and of (ii) the presence of polar lipids were characterised. In bulk, crystallisation of TG successively occurred with a α 2L (49.3 Å) structure, then the formation of longitudinal stackings of 44.5 and 34.5 Å of β′ form was interpreted as co-crystallisation of TG from CB and miglyol. The dispersion of TG in nanoparticles of about 400 nm induced a higher supercooling and changed their crystallisation properties. The formation of α 49.2 Å and β′ 45 Å structures corresponded to the segregation of TG from CB in solid phases while TG from miglyol remained liquid. Phospholipids with saturated fatty acid chains affected the thermal properties of TG, which demonstrated their localisation at the surface of the nanoparticles. DSC and XRD revealed to be very sensitive and adapted methods to increase the knowledge about the mechanisms of crystallisation in emulsion.

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References A ndrikopoulos , N.K. , C hiou , A. & M ylona , A. ( 2004 ): Triacylglycerol species of less common edible vegetable oils . Food Rev. Int. , 220 , 389 – 405

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Investigation of the complex thermal behavior of fats

Combined DSC and X-ray diffraction techniques

Journal of Thermal Analysis and Calorimetry
Authors: G. Keller, F. Lavigne, C. Loisel, M. Ollivon, and C. Bourgaux

The thermal behavior of three ural fats (displaying very different composition), cocoa butter (CB)2, lard, and a stearin obtained from anhydrous milk-fat (AMF) fractionation, were studied by both DSC and X-ray diffraction as a function of temperature (XRDT). To perform temperature explorations between −30‡C and +80‡C, at rates identical to those used for DSC and ranging from 0.1 K min−1 to 10 K min−1, a new set of X-ray sample-holders, temperature-controlled by Peltier effect, has been developed. It is shown that the three more stable polymorphic forms of CB were easily characterized by either X-ray diffraction or DSC, and existence of two Β-3L forms was confirmed. On the contrary, the more complex polymorphism of lard and AMF required combined examination by DSC and XRDT and the brightness of the synchrotron source for studies at the highest heating rates. Quantitative analysis of the long spacings of XRDT recordings is invaluable for interpretation of thermal events. For instance, it was found that the simultaneous formation of two polymorphic forms, of apparent long spacing of 34 and 42 å, at the onset of lard crystallization might explain the difficulty of its fractionation.

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Kohlwein, S. D. (2010) Triacylglycerol homeostasis: insights from yeast. J. Biol. Chem. 285 , 15663–15667. Kohlwein S. D. Triacylglycerol homeostasis: insights from yeast

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Dyck, D. J., Miskovic, D., Code, L., Luiken, J. J. and Bonen, A. (2000): Endurance training increases FFA oxidation and reduces triacylglycerol utilization in contracting rat soleus. Am. J. Physiol. Endocrinol. Metab. 278 , 778

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because of the presence of the more unsaturated triacylglycerols such as triolein [ 23 , 25 – 27 ]. Changes of crystallization DSC profiles occurring in the Evoo samples during the period in which they were subjected to the accelerated oxidative

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Abstract  

Fat fractions composed by different proportions of low (LMT) or high (HMT) melting temperature triacylglycerols were used, alone or in mixture with α-tocopherol for the preparation of oil-in-water protein stabilised nano-emulsions. Addition of α-tocopherol to the LMT or HMT fat fractions was accompanied by different changes in the emulsion characteristics such as fat droplet size distributions, under-cooling and polymorphic transitions, in parallel with different extent of α-tocopherol degradation reactions. Our results showed higher immobilisation pattern of α-tocopherol molecules and higher protection against degradation when incorporated in higher size fat droplets, which presented 2Lα → 2Lβ′ polymorphic transitions under cooling and re-heating cycles.

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In in vitro studies it was detected that the juice from the choleretic black radish root had hydrogen donating and d-field element-chelating abilities. The juice exhibited strong reducing power property and radical scavenging effect in H2O2/∙OH luminol system.

With the help of short term animal experiment we examined the in vivo effect of Raphanus sativus root juice on hyperlipidemia in rats.

A chemiluminescent study was applied to determine the total scavenger activity (TSC) of erythrocytes and plasma of untreated and treated animals. We also determined the different liver enzyme activities: alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and metabolite concentrations (cholesterol, triacylglycerols, total bilirubin, glucose) by spectrophotometry in the sera.

In our study, using experimental hyperlipidemic condition, it has been detected that black radish root juice could moderate the injurious effect of lipid rich diet in rats in vivo.

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Neutral lipids and phospholpids in the apple snail Pomacea bridgesii have been determined in the whole body, digestive gland-gonad complex (DGG), viscera, head-foot, shell, operculum, plasma, and hemocytes by high-performance thin-layer chromatography on silica gel plates. Plates were developed with petroleum ether-diethyl ether-glacial acetic acid, 80 + 20 + 1 ( v/v ), as mobile phase and sprayed with 5% phosphomolybdic acid to detect neutral lipids. Plates were developed with chloroform-methanol-water, 65 + 25 + 4 ( v/v ), and sprayed with 10% cupric sulfate to detect phospholipids. Triacylglycerols, free sterols, free fatty acids, steryl esters, phosphatidylcholine, and phosphatidylethanolamine were the major lipid fractions detected in the whole body, DGG, viscera, and head-foot. The major lipid fractions in the shell and operculum were free sterols and free fatty acids. The plasma and hemocytes contained free fatty acids as the major lipid fraction. The presence of these lipids suggests they are important to the metabolism and structure of the snail.

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The present work was carried out to uncover the effect of salinity stress on shoot moisture percentage, pigment content and lipid composition of Ephedra alata Decne. The results suggested that salinity caused significant decrease in plant moisture content. The chl. a, b and carotenoids showed significant decrease with increasing concentration of salt. Total pigment content also showed decline at all salt stress levels. Salt stress caused significant decrease in total lipids (TL), triacylglycerol (TG) and sterol (S) accompanied with an increase in diacylglycerol (DG), sterol ester (SE), and non-esterified fatty acids (FAA) of E. alata. Moreover, saline stress caused significant decrease in all phospholipid fractions except phosphatidic acid which increases during salt stress. Salinity stress resulted in increase of saturated fatty acids and decreases the percentage of un-saturated fatty acids in E. alalta.

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