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Food Science

Food Structure

Polymorphism

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Full-Text Articles in Life Sciences

Structure Of Margarines Made With Low Erucic Acid Rapeseed Oil, J. Hojerova, S. Schmidt, J. Krempasky Jan 1992

Structure Of Margarines Made With Low Erucic Acid Rapeseed Oil, J. Hojerova, S. Schmidt, J. Krempasky

Food Structure

Margarine based on hydrogenated low erucic acid rapeseed oil shows a strong tendency to produce an unacceptable grainy structure. This is caused by rapid transition of the B-form into the B-form of fat crystals. Sorbitan esters, monoacylglycerols, and a blend of acylglycerols were investigated as possible B-stabilizers. Polymorphic transitions were evaluated by visual assessment, examination by polarized light microscopy, and x-ray diffraction analysis in margarines prepared on a laboratory scale and containing varying amounts of stabilizers. The evaluation was extended over a 7-week period of storage at 10 C. Sorbitan esters of fatty acids were found to be the most ...


Emulsifiers As Additives In Fats: Effect On Polymorphic Transformations And Crystal Properties Of Fatty Acids And Triglycerides, J. Aronhime, S. Sarig, N. Garti Sep 1990

Emulsifiers As Additives In Fats: Effect On Polymorphic Transformations And Crystal Properties Of Fatty Acids And Triglycerides, J. Aronhime, S. Sarig, N. Garti

Food Structure

The role of emulsifiers in polymorphic transformations of fats and fatty acids is treated in this paper. Their effect as crystal modifiers in solution-mediated transformations (in fatty acids) is compared to that of a dynamic controller of polymorphic transformations in triglycerides. The importance of chemical structure both in the hydrophilic and in the hydrophobic moieties of the emulsifier for an inhibitory effect on phase transitions has been emphasized. The emulsifier solubility and crystallization behavior in different solvents are probably the main factors affecting its ability to interfere with the kinetics of solution-mediated transformations. On the other hand, certain requirements for ...


Fat Polymorphism And Crystal Seeding Effects On Fat Bloom Stability Of Dark Chocolate, T. Koyano, I. Hachiya, K. Sato Jan 1990

Fat Polymorphism And Crystal Seeding Effects On Fat Bloom Stability Of Dark Chocolate, T. Koyano, I. Hachiya, K. Sato

Food Structure

The effects of seeding with fine crystal powders on the physical properties of dark chocolate are re viewed in terms of the polymorphism and crystallization behavior of cocoa butter (CBJ and of its major fat constituents. The polymorphic structure of four symmetric mixed acids saturated -oleic-saturated (Sat-0- Sat) triacylglycerols (TAGs I [POP (1 ,3-dipalmitoyl-2- oleoyl-glyceroll ;SOS I 1 ,3-distearoyl-2-oleoyl-glycerol); AOA (1 ,3-diarachidoyl-2-oleoyl-glycerol); and BOB 11 ,3-dibehenoyl-2-oleoyl-glyceroi)J. and of tristearoylglycerol (SSSI are briefly explained. An attempt is made at replacing the currently used tempering meth ~ ad in the chocolate solidification process, by a simple cooling technique using fat seed crystals ...


Observation Of Seeding Effects On Fat Bloom Of Dark Chocolate, I. Hachiya, T. Koyano, K. Sato Jan 1989

Observation Of Seeding Effects On Fat Bloom Of Dark Chocolate, I. Hachiya, T. Koyano, K. Sato

Food Structure

Surface microstructures and polymorphism of seeded dark chocolate were observed with cryo-SEM, to clarify the effects of seeding on fat bloom stability of dark chocolate. Two thermal tests, cycling between 32 adn 20C (32/20) and 38 and 20 C (38/20), were applied to examine the fat bloom stability of the chocolate. We used three crystalline powders: Form VI of cocoa butter; the most stable B1 form of SOS (1,3-distearoyl-2-oleoylglycerol); and the second stable B2 form of BOB (1,3,-dibehenoyl-2-oleoylglycerol) as seed materials. Seeding with cocoa butter (Form VI) and SOS (B1) at concentrations of 0.5 ...


Physical And Molecular Properties Of Lipid Polymorphs - A Review, K. Sato Jan 1987

Physical And Molecular Properties Of Lipid Polymorphs - A Review, K. Sato

Food Structure

The physical and molecular properties of the polymorphism of stearic acid, oleic acid and SOS (1.3-distearoyl-2-oleoyl glycerol) are comparatively discussed. Temperature dependence of Gibbs energy (G-T relation) of three polymorphs of stearic acid; A, B and C, revealed close relationships to each other. The molecular structures subtly differed in these polymorphs. In contrast, three plymorphs of oleic acid, b , and y exhibited remarkably different characteristics. G-T relation showed more diversified features: in particular, the melting points of 9 and B differ by 3 C. An order-disorder transformation occured between 9 and y, as a result of conformational disordering the ...


Thermal Analysis Microscopy For The Study Of Phase Changes In Fats, J. M. Deman, A. N. Mostafa, A. K. Smith Jan 1985

Thermal Analysis Microscopy For The Study Of Phase Changes In Fats, J. M. Deman, A. N. Mostafa, A. K. Smith

Food Structure

An investigation was carried out using the Mettler FPBOO Thermosystem to study polymorphic transitions of several monoacid triglycerides and hydrogenated Canola oil. The system includes a central processing unit connected with a thermal microscopy hot stage that allows the measurement of heat flow to the scrnple . Scanning electron microscopy was also used to examine the same samples after osmium tetroxide fixation . The results obtained relate phase transitions occurring during heating and cooling with the morphology of the various crystal structures.


Microscopy In The Study Of Fats And Emulsions, J. M. Deman Jan 1982

Microscopy In The Study Of Fats And Emulsions, J. M. Deman

Food Structure

Plastic fats consist of a three dimensional network structure of crystals in which liquid oil is trapped. This crystal network is held together by weak attractive forces, the nature of which is nut definitely e stablished. Crystal size is dependent on temperature history and is subject to polymorphic transitions which greatly affect the microstructure of the system. The microstructure of fats has been investigated by using polarized light microscopy, electron microscopy and X-ray diffraction analysis . Recently, a permeametric method has been developed which enables the determination of the specific surface area of the crystals in a fat. This method is ...