ABSTRACT For optimization of biochemical processes in food and pharmaceutical industries, the evaluation of enzyme inactivation kinetic models is necessary to allow their adequate use. Kinetic studies of thermal inactivation of β-galactosidase from Aspergillus oryzae were conducted in order to critically evaluate mathematical equations presented in the literature. Statistical analysis showed that Weibull model presented the best adequacy to residual enzymatic activity data through the processing time and its kinetic parameters as a function of the temperature, in the range of 58-66 ºC. The investigation suggests the existence of a non-sensitive heat fraction on the enzyme structure, which is relatively stable up to temperatures close to 59 ºC. Thermodynamic parameters were evaluated and showed that such β-galactosidase presents activation energy of 277 kJ mol-1 and that the enzyme inactivation is due to molecular structural changes. Results shown that the enzyme is quite stable for biotechnological applications.
Although the greatest variety of Brazilian flora is in the Amazon region, the Southern region of Brazil also has an estimated number of at least 5,000 species of vascular native plants. These species have been neglected as potential food sources, remaining unknown and under-utilized and limiting the potential variety in the diet of Brazilians and other peoples. Therefore the aim of this study was to characterize the mineral composition and content present in seven native fruit species of Southern Brazil using inductively coupled plasma optical emission spectrometry (ICP-OES). The essential element concentrations in the fruit samples were higher or similar to the values reported for traditional fruits. The araticum-do-mato fruit samples had high concentrations of the elements Ca, K, and Cu, and trace elements such as Pb and Sr. Mandacaru-de-três-quinas had predominance of Ba, Bi, and Ga, and the essential elements Mg and Mn. Uvaia and guabiroba had the highest levels of Al and Cr, but uvaia had high levels of Fe and Zn. The pindo palm had high amounts of Cd and Ni, and the yellow guava had high concentrations of Na, while red guava had high levels of Co.
This research describes the base wines characterization and differentiation (cultivars Chardonnay and Pinot Noir) from Serra do Nordeste and Serra do Sudeste of Rio Grande do Sul by physicochemical parameters and mineral elements followed by multivariate statistical analysis. Nine physicochemical parameters (density, alcoholic content, total dry extract, reduced dry extract, total acidity, volatile acidity, fix acidity, pH and reducing sugars) were analyzed by infrared spectrofotometry and eleven mineral elements (Al, B, Ba, Ca, Cu, Fe, K, Mg, Mn, Na and Sr) by inductively coupled plasma optical emission spectrometry (ICP-OES). Elements K, Mg, and Ca were founded in higher concentrations and Ba, Fe, Sr, and Al were founded in lower ones. Principal Component Analysis (PCA) showed a natural separation tendency between wines from Serra do Nordeste and Serra do Sudeste. Five descriptors were obtained by Discriminant Analysis (DA) for base wines from cultivar Chardonnay (Mg, Ca, Mn, pH and alcoholic content) and six descriptors for base wines from cultivar Pinot Noir (B, Mn, Fe, Na, pH and volatile acidity). These descriptors were capable to classify samples of base wines according to geographical origin. Mn and Mg elements seem to be the elements with higher discrimination capacity between base wines from northwest Serra and Southeast Serra.
Os objetivos deste trabalho foram caracterizar e diferenciar vinhos-base para espumante (cultivares 'Chardonnay' e 'Pinot Noir') provenientes da Serra do Nordeste e Serra do Sudeste do Rio Grande do Sul por meio de parâmetros físico-químicos e elementos minerais combinados com técnicas de análise multivariada. Foram analisados nove parâmetros físico-químicos (densidade, grau alcoólico, extrato seco total, extrato seco reduzido, acidez total, acidez volátil, acidez fixa, pH e açúcares redutores), por espectrofotometria no infravermelho, e 11 elementos minerais (Al, B, Ba, Ca, Cu, Fe, K, Mg, Mn, Na e Sr), por espectrometria de emissão ótica com plasma indutivamente acoplado (ICP-OES). Os elementos encontrados em maiores concentrações foram K, Mg e Ca e, em menores concentrações, Ba, Fe, Sr e Al. A Análise de Componentes Principais (ACP) mostrou que há uma tendência natural de separação entre os vinhos-base da Serra do Nordeste e Serra do Sudeste. Por meio da Análise Discriminante (AD) foram obtidos cinco descritores (Mg, Ca, Mn, pH e grau alcoólico) para os vinhos-base da cultivar 'Chardonnay' e seis descritores (B, Mn, Fe, Na, pH e acidez volátil) para a cultivar 'Pinot Noir', com capacidade de classificar as amostras de vinhos-base de acordo com a origem geográfica. Os elementos Mn e Mg parecem ser aqueles com maior capacidade de discriminação entre os vinhos-base da Serra do Nordeste e Serra do Sudeste.
Some chemical and microbiologycal aspects of one hundred (100) different wines bought in the local stores were studied in this work. Minimum, maximum, and average values for total and free SO2, ethanol, total and volatile acidity, total sugars and pH are given for fifty one (51) white, forty two (42) reds, seven (7) pink wines. Also, the amount of yeasts, other fungi, lactic and acetic bacteria are given for all the wines. Higher average values of total and free SO2 (124,2 and 18,9mg/l respectively) were found in the white wines, as expected. There was a direct relationship between the tow level of free SO2 and the contamination with yeasts and bacteria, also expected. However, red wines were more contaminated with yeasts than white wines, what was not expected.
Foram estudados aspectos químicos e microbiológicos de cem (100) diferentes vinhos adquiridos no comércio do Rio Grande do Sul. Valores mínimos, máximos e médios de anidrido sulfuroso livre e total, etanol, acidez volátil e total, açúcares e pH são descritos para cinqüenta e um (51) vinhos brancos, quarenta e dois (42) tintos e sete rosados, assim como a quantidade de leveduras, fungos e bactérias acéticas e lácticas. Valores médios elevados de anidrido sulfuroso total e livre (124,2 e 18,9mg/l respectivamente) foram encontradas em vinhos brancos. Houve correlação direta entre a maior contaminação de amostras com o baixo teor de anidrido sulfuroso livre, como esperado. Vinhos tintos estavam mais contaminados com leveduras que os brancos, o que não era esperado.