a b s t r a c tThe manufacture of composite biofilms of alginate and LM-pectin crosslinked with calcium ions requires a two-step contact with Ca 2+ : initially a low-structured pre-film is formatted which is further crosslinked in a second contact with a more concentrated Ca 2+ solution containing plasticizer. This research evaluated the influence of the plasticizer (glycerol) concentration (1-15% w/v) in this finishing reticulation step on final films characteristics. The results indicated that the extent of the simultaneous Ca 2+ crosslinking and plasticization with glycerol was determined by the level of structural organization obtained in the pre-reticulation. Increasing the glycerol concentration of the crosslinking solution increased film solubility in water, moisture content, volumetric swelling and flexibility and decreased the resistance to tensile stress. Transparent alginate and pectin composite films with acceptable mechanical properties, low solubility and limited degree of swelling were obtained with 10% glycerol in the second contact solution.

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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The release of potassium sorbate from alginate fi lms was evaluated considering different active agent concentrations in the fi lm and three levels of alginate crosslinking. The mechanism involved in the diffusional process was investigated using the Power Law Model. The results indicated that potassium sorbate diffusion in alginate fi lms has characteristics of Fickian and non-Fickian behaviour. Effective diffusion coeffi cients obtained using the solution in series derived from Fick's Second Law are close to values obtained by the short-time solution, indicating that the infl uence of swelling on effective diffusivity, although perceptible, is small, allowing the use of an average effective diffusivity. The values of effective diffusivity found indicate that alginate fi lms have a potential use as systems for release of active substances.