In this study, biopolymer-based pH-sensitive hydrogels have been successfully prepared using alginate, κ-carrageenan and pectin aimed at the encapsulation of pancreatin (hydrolytic enzymes like α-amylase, lipase and protease) so as to preserve enzymatic activities. Hydrogels have been characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), swelling degree and swelling profile. Encapsulation efficiency and in vitro studies on delayed release have also been evaluated. All hydrogels presented low swelling degree and enzyme release in a gastric medium. On the other hand, high swelling degree and enzyme release were observed in an intestinal medium. Alginate hydrogel achieved optimal results concerning encapsulation efficiency (18, 68 and 53% for α-amylase, lipase and protease, respectively) and delayed release (363, 7,673 and 17,497 U for α-amylase, lipase and protease, respectively) which has been afterwards compared to a commercial pancreatin formulation (CreonTM 10,000). Thus, it presented better performance than its commercial formulation, mainly in respect of lipase.

The present study reports the synthesis and characterization of complexes formed among humic (HA) and fulvic acids (FA) derived from poultry wastes and ions Cu2+, Fe2+ and Zn2+. The release of such metals in a buffer solution simulating the soil solution was also evaluated. After complexation, the Fourier transform infrared (FTIR) spectra presented alterations in the absorption bands related to changes in the humic structure, thus indicating the complexation with phenolic and carboxylic groups. Thermogravimetric analyses demonstrated that complexed metals decreased the thermal stability of humic substances. Analyses by atomic absorption spectroscopy (AAS) demonstrated that the release of metals is directly related to the origin of the sample, type of interaction of metal and humic structure and conditions of the medium in which the complex is inserted.

Roasted and ground coffee is targeted by fraudulent addiction of products. In this way the determination of contaminants in coffee has economic and nutritional importance. In this study, the coffee adulteration by corn were detected using DSC (differential scanning calorimetry) and FTIR (Fourier transform infrared spectroscopy) coupled to PCA (principal component analysis), and PLS (partial least squares) models. Three different levels of roasted and ground Coffea arabica L. were used to prepare mixtures with roasted and ground corn. The level of adulteration used was between 0.5 to 40% (m/m). It was observed that both DSC and FTIR coupled with PCA are able to discriminate adulterated from unadulterated samples of coffee by corn at levels below 1%. PLS models were built with DSC and FTIR data reaching good correlation between the values of estimated and reference concentrations, with RMSECV (root mean square error of cross-validation) lower than 3.5% for DSC data and 2.7% for FTIR data.

O processo de eletrooxidação da 1,2-benzopirona (BP) foi avaliado através de medidas de voltametria linear e espectroscopia de impedância eletroquímica sobre o eletrodo de carbono vítreo em tampão fosfato dibásico de potássio. O número de elétrons envolvidos na eletrooxidação é um e o produto formado é uma cetona. O produto da oxidação fica adsorvido na superfície do eletrodo formando um filme, o qual bloqueia os sítios ativos e a espessura do filme aumenta após medidas consecutivas. As condições de analise foram otimizadas usando planejamento fatorial e matriz Doehlert. A metodologia eletroquímica foi comparada com a cromatografia líquida de alta eficiência (HPLC) com um limite de detecção para a BP de 26,4 µmol L-1. Os resultados voltamétricos foram estatisticamente semelhantes aos obtidos por HPLC, mas o método proposto é mais rápido, simples, de fácil aquisição e de alta sensibilidade, e não exige grandes quantidades de solventes orgânicos.

The electrooxidation of 1,2-benzopyrone (BP) was assessed via linear voltammetry and electrochemical impedance spectroscopy on a glassy carbon electrode in dibasic potassium phosphate buffer. The oxidation process for BP requires one electron and forms a ketone. This oxidation product was adsorbed by the electrode surface to form a film that blocks active sites and increases in thickness over consecutive measurements. The oxidation conditions were optimized using factorial design and Doehlert matrices. This electrochemical method was compared to high performance liquid chromatography (HPLC), which has a detection limit of 26.4 µmol L-1 for BP. The voltammetric results were statistically similar to those from HPLC; however, the method was faster, simpler, more easily acquired, more sensitive, and required less organic solvent.

O presente trabalho visou a aplicação da enzima quitinolítica purificada da linhagem Cellulosimicrobium cellulans 191 e da preparação comercial de papaína na hidrólise da quitina coloidal. A quitina coloidal foi caracterizada quanto ao grau de desacetilação e apresentou GD de 14% por espectroscopia na região do infravermelho. A quitinase purificada hidrolisou a quitina coloidal liberando di-N-acetilquitobiose, enquanto que a preparação comercial de papaína atuando sobre o mesmo substrato formou di-N-acetilquitobiose e tri-N-acetilquitotriose. A estrutura química dos aminoglucanooligossacarídeos foi elucidada por espectrometria de massa.

The aim of this work was the application of purified chitinolytic enzyme from Cellulosimicrobium cellulans 191 and the commercial papain in the hydrolysis of colloidal chitin. The latter was characterized with regard to the degree deacetylation (GD), with a GD of 14% being obtained using infrared spectroscopy. The purified chitinase hydrolysed the colloidal chitin and formed di-N-acetylchitobiose, while the commercial papain acting on the same substrate formed di-N-acetylchitobiose and tri-N-acetylchitotriose. The aminoglucanoligosaccharides chemical structure was elucidated by mass spectrometry.