Fats, polymorphism

Sato, K Ueno, S. Crystallization, transformation and microstructures of polymorphic fats in colloidal dispersion states. Curr Opin Colloid Interface Sci, 2011 16 384-90. 

JB Harris, CN Keulemans, LA Milton, EJG Roest. Dry fractionation process for separation of polymorphic fats and oils as stable crystals. Patent WO 9605279,1996. RW Hartel, L Baomin, S Yuping. Continuous crystalhsation system with controlled nucleation for milk fat fractionation. Patent Appl WO 9851753 [US 46166 (19970512)], 1998. 

Schlichter-Aronhime J, GartiN. Solidification andpolymorphism in cocoabutter and the bloom-ingproblems. in Crystallisation and Polymorphism Fats Fatty Acids (Surfactant Science Series 31). New York Marcel Dekker, 1988 pp. 363-393. 

Absorption of x-rays by a powdered sample of soHd fat has been a useful method for determination of polymorphic character as discussed eadier. The a, and P forms may be distinguished however, interpretation is made more difficult because subsets of the P and P forms have often been encountered. Also, a fat may contain mixtures of polymorphic forms and properties may therefore be difficult to relate to the spectra. 

N. Garti and K. Sato, Crystallisation and Polymorphism of Fats andFatty Mcids Marcel Dekker, Inc., New York, 1988. 

Tempering. The state, or physical stmcture, of the fat base in which sugar, cocoa, and milk soHds are suspended is critical to the overall quaHty and stabiHty of chocolate. Production of a stable fat base is compHcated because the cocoa butter in soHdified chocolate exists in several polymorphic forms. Tempering is the process of inducing satisfactory crystal nucleation of the Hquid fat in chocolate. 

Control of the polymorphic forms in cocoa butter is further compHcated by the presence of other fats such as milk fat. The fat in a chocolate can be likened to the mortar between the bricks in a mason s wall. The soHd particles in a weU-conched chocolate bed down better than the soHds in a coarsely refined and poorly mixed one (30). 

Crystallization and Polymorphism of Fats and Fatty Acids, edited by Nissim Garti and Kiyotaka Sato... 

Microemulsions and Related Systems Formulation, Solvency, and Physical Properties, edited by Maurice Bourrel and Robert S. Schechter Crystallization and Polymorphism of Fats and Fatty Acids, edited by Nissim Garti and Kiyotaka Sato... 

Nemeth A, Szakmary K, Kramer J, Di-nya E, Pados G, Fust G, et al. Apolipo-protein E and complement C3 polymorphism and their role in the response to gemfibrozil and low fat low cholesterol therapy. Eur J Clin Chem Clin Biochem 1995 33 799-804. 

Kaneko E, Polymorphism and phase transitions of fatty acids and acylglycerols, in Crystallization Processes in Fats and Lipid Systems, Garti N. and Sato K., eds., Marcel Dekker, New York, 2001, 53-97. 

Cocoa butter NF is defined as the fat obtained from the seed of Theobroma Cacao Linne (Family Sterculiaceae) (44). Cocoa butter softens at 30°C and melts at 34°C. It contains four different forms alpha, beta, beta prime, and gamma with melting points of 22°C, 34°C to 35°C, 28°C and 18°C, respectively. The beta form is the most stable and is desired for suppositories. The biggest challenge with the polymorphism of cocoa butter is the impact of the manufacturing process on the characteristics of the suppository itself. When cocoa butter is hastily melted at a temperature greatly exceeding the minimum required temperature and then quickly chilled, the result is metastable crystalline form (a crystals), which may not even... 

Timms, R. E. 1980. The phase behaviour and polymorphism of milk fat, milk fat fractions and fully hardened milk fat. Aust. J. Dairy Technol. 35, 47-53. 

In many instances, TGs exist in polymorphic forms. Crystal structure is very important to the properties of margarines, shortenings, and specialty fats. The very unstable a form is readily transformed to the more stable ft form, which in some TGs has a higher melting point (more stable) than the /3 form. In single-acid TGs, the order is a — f3 — a, but some mixed TGs show a lower-melting (less stable) (3 form. This is further complicated by the existence of multiple / and /3 forms, depending upon the detailed TG structures at hand. 

The importance of being able to determine the geometrical isomers of TGs in partially hydrogenated fats can be ascribed to their effect on the physical behavior of the fats, such as their polymorphic behavior and melting properties. 

Localized NMR spectroscopy, which is often called as MRS in comparison with MRI, is not so familiar technique in food science, because a specific pulse sequence such as ISIS and a facility which can precisely follow the pulse sequence without any contamination from other position is needed for localization of position. The localized NMR is usually used together with NMR imaging. The study of solid/liquid ratios, fat structure and polymorphism and the kinetics of fat crystallization was reviewed [24], The potential of applications in food process development and control was offered. The localized spectra of sausages in areas of 0.3 mm X 0.05 mm (thickness of sample =1.5 mm) were obtained by the spin echo 2DFT method [113], in which the difference in the tissue structure was discussed with relation to the process and original materials. McCarthy et al. determined mobility of water in foams by using a localized spectroscopy [114]. T2 relaxation time varies in the foam as function of diameter and its variation was analyzed by the classic 2-state fast exchange model. 

Hernquist, L. (1984) Polymorphism of Fats. Thesis, Lund University, Lund, Sweden. 

Winter, A., Kramer, W., Werner, F.A.O., Rollers, S., Kata, S., Durstewitz, G., Buitkamp, J., Womack, J.E., Thaller, G., Fries, R. 2002. Association of a lysine-232/alanine polymorphism in a bovine gene encoding acyl-CoA diacylglycerol acyltransferase (DGAT1) with variation at a quantitative trait locus for milk fat content. Proc. Nat. Acad. Sci. (USA)... 

The dispersed state has a considerable effect on fat crystal polymorphism. Lopez et al. (2000, 2001c) observed that crystallization in milk fat globules is more disordered than in bulk fat. On slow cooling, milk fat crystallizes in the a form in cream (Lopez et al., 2001a), whereas in anhydrous milk fat, it crystallizes first in the (3 form and then in the a form (Lopez et al., 2001b). Rapid cooling of cream or anhydrous milk fat from 60 to 4°C leads to the formation of a crystalline structures, which transformed into (3 structures... 

Polymorphism refers to the situation in which materials of the same chemical composition possess different sub-cell packings in the solid state (Small, 1986). Figure 7.3 compares the level of structure for the unit cell and sub-cell in crystalline fats. Polymorphism arises from both variations in the tilt of TAG molecules in a bilayer and from variations in the hydrocarbon chain packing (Larsson, 1994). 

---