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This work aimed to compare methods for the formation of complexes of bixin and curcumin with β-cyclodextrin (β-CD) and to evaluate the stability of the complexes formed by these methods and their food applications. The stoichiometric relationship between curcumin and β-CD was 1:2 and that between bixin and β-CD was 1:1. Curcumin-β-CD and bixin-β-CD complexes formed by kneading, coprecipitation, and simple mixing were evaluated by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), or nuclear magnetic resonance (NMR-H). For both curcumin and bixin, the best method of complexation was coprecipitation. Complexation of colorants with β-CD promoted an intensification of color and increased water solubility; however, stabilization in the presence of light occurred only for bixin. Application of curcumin-β-CD in cheese and yogurt and bixin-β-CD in the curd did not alter the initial characteristics of the products, which were sensorialy well accepted. Therefore, the complexation of these natural colorants with β-CD favors their use in low-fat foods, broadening the field of industrial application.

This work deals with the transesterification of palm oil with ethanol in a solvent free system using lipase from different sources (Thermomyces lanuginosus, Pseudomonas fluorescens, Burkholderia cepacia, Penicillium camembertii, and Candida antarctica, porcine pancreatic) immobilized on hybrid support polysiloxane-poly-(vinyl alcohol). This is an exceptional option for the Brazilian biodiesel production, because both palm oil and ethanol are readily available in the country. The enzyme source showed strong influence on the transesterification yields, and the best performance was attained with the lipase from Pseudomonas fluorescens that reached almost full conversion (=98 %) in less than 24 h of reaction. The purified product (biodiesel) was straw yellow in color and essentially odorless. Purity of the fatty acid ethyl ester was found to be high having no glycerol bound as verified by NMR 13 C (APT, attached proton test). In addition, the other properties such as low water content (0.02%), specific gravity (0.8), and viscosity (4.97 cSt) are in accordance with specifications recommended by the ASTM D6751 to be used as biofuel.

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-The objective of this study was to evaluate the immobilization of lipase on a chitosan support by physical adsorption, aiming at its application in hydrolytic and synthetic reactions. Two types of chitosan (flakes and porous) were used for immobilizing lipase from a microbial source (Candida rugosa) and animal cells (porcine pancreas). The best results for recovery of total activity after immobilization were obtained for microbial lipase and porous chitosan beads. This set was selected for further immobilization studies, including full characterization of the immobilized derivative in aqueous and organic media. In aqueous medium, the operational and thermal stabilities of this preparation were quantified. In organic medium, the direct synthesis of n-butyl butyrate in organic solvent was chosen as a model reaction. The influence of several parameters, such as temperature, initial butyric acid concentration and amount of enzyme in the reaction system, was analyzed. Production of n-butyl butyrate was optimized and an ester yield response equation was obtained, making it possible to predict ester yields from known values of the three main factors. Use of this immobilized preparation was extended to the direct esterification of a large range of carboxylic acids (from C 2 to C 12 ) with a variety of alcohols (from C 2 to C 10 ).