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Crystallization of fats is a determinant physical event affecting the structure and properties of fat-based products. The stability of these processed foods is regulated by changes in the physical state of fats and alterations in their crystallization behavior. Problems like polymorphic transitions, oil migration, fat bloom development, slow crystallization and formation of crystalline aggregates stand out. The change of the crystallization behavior of lipid systems has been a strategic issue for the processing of foods, aiming at taylor made products, reducing costs, improving quality, and increasing the applicability and stability of different industrial fats. In this connection, advances in understanding the complex mechanisms that govern fat crystallization led to the development of strategies in order to modulate the conventional processes of fat structuration, based on the use of crystallization modifiers. Different components have been evaluated, such as specific triacyglycerols, partial glycerides (monoacylglycerols and diacylglycerols), free fatty acids, phospholipids and emulsifiers. The knowledge and expertise on the influence of these specific additives or minor lipids on the crystallization behavior of fat systems represents a focus of current interest for the industrial processing of oils and fats. This article presents a comprehensive review on the use of crystallization modifiers in lipid systems, especially for palm oil, cocoa butter and general purpose fats, highlighting: i) the removal, addition or fractionation of minor lipids in fat bases; ii) the use of nucleating agents to modify the crystallization process; iii) control of crystallization in lipid bases by using emulsifiers. The addition of these components into lipid systems is discussed in relation to the phenomena of nucleation, crystal growth, morphology, thermal behavior and polymorphism, with the intention of providing the reader with a complete panorama of the associated mechanisms with crystallization of fats and oils.

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Chemical interesterification is currently the main alternative for the production of plastic fats containing no trans fatty acids. However, directing the industrial application of an interesterified fat requires a complete understanding of its physicochemical, functional and technological properties, and also of its stability during and after processing. The objective of the present article was to carry out an ample review of the experimental methodologies applied to the study of interesterified fats. The methodologies considered include techniques employed in the investigation of the triacylglycerol composition, solid fat content, crystallization kinetics, thermal behavior, polymorphism, microstructure, and consistency. The methodologies considered include some official methods currently in use and new techniques recently developed and employed. Sample preparation methods, interpretation of the results and the results recently published in the literature in question are also detailed and discussed.

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