Review of the polymorphism of saturated even glycerides

Lutton, Évelyne

doi:10.1007/bf02634906

Cited by 151 publications

(102 citation statements)

References 37 publications

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“…This sharp 4.15 A reflection is also well characterized. For example, wide angle diffraction patterns of long chain paraffins in a crystalline hexagonal phase feature a sharp ring at 4.15 A (13,16,21). Its appearance in wide angle patterns from membranes also reflects an ordered crystalline or gel phase of the lipid in which the hydrocarbon chains form a rigid hexagonal lattice (7,8,27,28).…”

Section: Resultsmentioning

confidence: 99%

Lipid Crystallization in Senescent Membranes from Cotyledons

McKersie

Thompson²

1977

Plant Physiol.

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Lipid transition temperatures for rough and smooth microsomal membranes isolated from bean (Phaseolus vulgaris) cotyledon tissue at various stages of germination were determined by wide angle x-ray diffraction. The transition temperatures were established by recording diffraction patterns through a temperature series until a sharp x-ray reflection centered at a Bragg spacing of 4.15 A and denoting the presence of crystalline lipid was discernible. For rough and smooth microsomes from 2-day-old tissue, the transitions occurred at 0 C and 3 C, respectively, indicating that at this early stage in the germination sequence the membrane lipid is entirely liquid-crystalline at physiological temperture. By the 4th day of germination, the transition temperatures had increased to 32 C for smooth microsomes and 35 C for rough microsomes, indicating that at 29 C, which was the growth temperature, portions of the membrane lipid were crystalline. During the later stages of germination, the transition temperature for smooth microsomes continued to rise through 44 C at day 7 to 56 C at day 9, by which time the cotyledons were extensively senescent and beginning to abscise. There was also a dramatic increase in the proportion of membrane lipid in the crystalline phase at 29 C. By contrast, the rough microsomes showed little change in transition temperature and only a dight increase in the proportion of crystalline lipid during this late period in germination. The data indicate that substantial amounts of the lipid is senescing membranes are crystalline even at physiological temperature. Moreover, there is a temporal correlation between the appearance of this crystality and loss of membrane function, suggesting that the two may be causally related.The onset of senescence in cotyledons of germinating Phaseolus vulgaris is marked by a general metabolic decline which includes deterioration of membrane function. Plasma membranes, for example, exhibit decreased cation-sensitive ATPase and cholinesterase activities as well as a reduced capability for ATP-dependent cation transport (12,14). This loss of function correlates temporally with age-dependent alterations in the protein complement of the membrane (15). The enzymic activities of microsomal membranes also decline as senescence intensifies, and the levels of microsomal phospholipid phosphate decrease indicating that there is a structural disassembly of these membranes (18).There is increasing evidence that the physical state of membrane lipid is an important factor in determining such key membrane functions as enzyme activity and permeability. By means of Arrhenius plots it has been demonstrated for certain membrane-bound enzymes that temperature-induced changes in activation energy correlate with phase transitions in the membrane lipid (5, 6, 9, 25). In addition, the permeability of lipid vesicles and natural membranes can be altered by factors known to influence membrane fluidity (4,24,31 The rough microsomes were further purified by centrifugation through 1.8 M sucrose ...

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Section: Resultsmentioning

confidence: 99%

Lipid Crystallization in Senescent Membranes from Cotyledons

McKersie

Thompson²

1977

Plant Physiol.

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“…The long spacing associated with the α polymorph of high-melting PS has been previously reported at 46 Å, with those of PPP, PPS/PSP, PSS/SPS, and SSS α crystals at 46.8, 47.6/46.7, 48.5/49.2, and 50.6 Å, respectively. [42,43] At the same temperature, a PS WAXD diffraction peak appeared at 4.18 Å (Fig. 5(d)), corresponding to the formation of α crystals in PO and its fractions.…”

Section: Polymorphismmentioning

confidence: 95%

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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“…There are four mostly common polymorphs in TAG phase transformations (sub-a-phase, aphase, b'-phase and b-phase). These phases have been identified in tristearin (StStSt) [4,5] or triolein (OOO) [6,7]. The a-phase of TAG -classified as a rotator phase (Fig.…”

Section: Introductionmentioning

confidence: 99%

Effect of unsaturated acyl chains on structural transformations in triacylglycerols

Mykhaylyk

Martin

2009

Euro J Lipid Sci & Tech

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Simultaneous time-resolved small-angle and wide-angle X-ray scattering has been used in the study of the isothermal crystallization behavior, after quenching, of triacylglycerols (TAG) with 18 carbons in the hydrocarbon chains. Saturated, unsaturated TAG, their blends and mixed saturated/unsaturated TAG were studied. The mixed saturated/unsaturated TAG and their blends form an a 2 -phase with a longitudinal packing different from two-chain and three-chain packings, which distinguishes them from the other fats. The unstable a 2 -phase, observed at the initial stage of crystallization of mixed saturated/unsaturated TAG, is classified as a transient mesophase. Two dimeric units proposed for a structural model of the a 2 -phase have been used to describe the structural organization of TAG molecules in the liquid state.

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Review of the polymorphism of saturated even glycerides

Cited by 151 publications

References 37 publications

Lipid Crystallization in Senescent Membranes from Cotyledons

Lipid Crystallization in Senescent Membranes from Cotyledons

Composition and crystallization behavior of solvent-fractionated palm stearin

Effect of unsaturated acyl chains on structural transformations in triacylglycerols

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