Dionísio Borsato

Extracellular β-glucosidase production by the yeast Debaryomyces pseudopolymorphus UCLM-NS7A: optimization using response surface methodology

beta-Glucosidase production by Debaryomyces pseudopolymorphus UCLM-NS7A using a simple nutrient medium containing cellobiose was evaluated under several biochemical and physiological parameters in submerged fermentation. Enzyme induction was also examined using different carbon and nitrogen sources. Cellobiose and ammonium nitrate were the best C and N sources to enhance beta-glucosidase production. The addition of NaCl, MgSO(4), yeast extract, ethanol and Tween 80 to the nutrient medium before inoculation was also compared. A factorial design to optimize enzyme production was developed using four variables that most influenced beta-glucosidase production and data analyzed by the response surface method. Optimal conditions to produce beta-glucosidase in shake-flasks were 1.25% cellobiose, 0.05% Tween 80, 0.4% NH(4)NO(3) over 72 hours. In another factorial design to further increase enzyme production, a lab fermenter using prior-determined shake-flask optimized conditions resulted in higher beta-glucosidase titres at 72 hours, pH controlled at 6.25 and agitation of 200 rpm.

Iogurte de soja suplementado com oligofrutose e inulina

People are getting more conscious about the relationship between food and health. Consequently, industry looks for new alternatives to develop food with good acceptance and with ingredients able to improve health. Soy, prebiotics such as oligofructose and inulin have a great application potential in food industry due to their functional properties. The aim of this work was to determine, using the Surface Response Methodology, the best conditions to the development of a soy yogurt supplemented with oligofructose and inulin. A 33 incomplete design was used, having oligofructose (%), inulin (%) and fermentation time (h) as independent variables, and pH and titrable acidity as responses. Regression analysis showed that models obtained were predictive. The optimization pointed out for the formulation containing 14.24% of oligofructose, 4.43% of inulin and 6 hours, as the best conditions to make soy yogurt. This formulation presented pH value of 4.6 and acidity of 0.37%. The chemical compostion was 16.2% of carbohydrates 2.01% of fat; 3.54% of protein; 0.40% of ash; and 77.85% of moisture. Calcium, iron and sodium content were 37; 0.99 and 15mg/100g, respectively. Therefore, oligofructose and inulin may be used to supplement soy yogurt, resulting in a product with functional ingredients.

Kinetic and thermodynamic parameters of biodiesel oxidation with synthetic antioxidants: simplex centroid mixture design

Temperatures influence on biodiesel oxidation was evaluated by kinetic and thermodynamic data in biofuel from soybean oil and lard with synthetic antioxidants: butylatedhydroxyanisol (BHA), butylatedhydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), and propylgallate (PG) by simplex centroid mixture design. The kinetic parameters ware obtained by Arrhenius equation and showed that addition of antioxidants in all tests increased activation energy (Ea) and that TBHQ and PG were more efficient and presented synergistic effect. BHT and BHA were the least efficient, as well as their mixtures. The thermodynamic activation parameters of the reactions, evaluated by the Eyring equation and based on the theory of the activated complex (ACT), indicated no spontaneous processes (∆G‡ > 0) with positive ∆H‡ values and positive and negative ∆S‡ values. The application of simplex centroid mixture design, using Ea as response, showed the optimised value of 174.46 kJ mol-1 for a mixture containing 33.33 and 66.67% of TBHQ and PG, respectively.

Study of oxidation kinetics of b100 biodiesel from soybean and pig fat: activation energy determination.

The quality of biodiesel is extremely important for its commercialization and use; oxidation of biodiesel is a critical factor because it decreases the fuel storage time. A commercial biodiesel was mixed with synthetic antioxidants, according to a simplex-centroid experimental mixture design, and its stability was evaluated through induction period and activation energy. In all trials, addition of antioxidants increased activation energy in the mixtures containing tertiary butylhydroquinone (TBHQ). When a mixture containing 50% TBHQ and 50% butylated hydroxyanisole was used, synergistic effect was observed, and the major activation energy obtained was 104.43 kJ mol-1.

Aplicação do delineamento simplex-centroide no estudo da cinética da oxidação de biodiesel B100 em mistura com antioxidantes sintéticos

Antioxidants are an alternative to prevent or slow the degradation of the biofuel. In this study, it was evaluated the oxidative stability of B100 biodiesel from soybean oil in the presence of three commercial synthetic antioxidants, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ), pure or blended, from the experimental design of simplex-centroid mixture. The reaction order and rate constant were also calculated for all tests. The treatment containing pure TBHQ proved to be the most effective, proven by design, the optimum mix obtained and the rate constant. Binary and ternary mixtures containing TBHQ also showed appreciable antioxidant effect.

Simulation of NaCl and KCl mass transfer during salting of Prato cheese in brine with agitation: a numerical solution

The association of dietary NaCl with arterial hypertension has led to a reduction in the levels of this salt in cheeses. For salting, KCl has been used as a partial substitute for NaCl, which cannot be completely substituted without affecting product acceptability. In this study a sensorially adequate saline solution (NaCl/KCl) was simultaneously diffused during salting of Prato cheese in brine with agitation. The simultaneous multicomponent diffusion during the process was modeled with Ficks second generalized law. The system of partial differential equations formed was solved by the finite element method (FEM). In the experimental data concentration the deviation for NaCl was of 7.3% and for KCl of 5.4%, both of which were considered acceptable. The simulation of salt diffusion will allow control and modulation of salt content in Prato cheese, permitting the prediction of final content from initial conditions.

Cinética da oxidação de biodiesel de óleo de soja em mistura com TBHQ: determinação do tempo de estocagem

Synthetic antioxidants are an alternative to prevent or retard the degradation of biofuels made from vegetable oils. In this study, it was evaluated the oxidative stability of B100 soybean oil biodiesel, in the presence of tercbutylhydroquinone (TBHQ). The results showed that the induction period, that precedes the seeding process, was delayed in the presence of the antioxidant. Moreover, the obtained results suggest that the B100 biodiesel containing TBHQ can present a storage time at 25 oC, three times longer than the estimated time for the pure B100.Synthetic antioxidants are an alternative to prevent or retard the degradation of biofuels made from vegetable oils. In this study, it was evaluated the oxidative stability of B100 soybean oil biodiesel, in the presence of tercbutylhydroquinone (TBHQ). The results showed that the induction period, that precedes the seeding process, was delayed in the presence of the antioxidant. Moreover, the obtained results suggest that the B100 biodiesel containing TBHQ can present a storage time at 25 oC, three times longer than the estimated time for the pure B100.

Optimized Neural Network for Instant Coffee Classification through an Electronic Nose

Flavor is one of the most important features of food, especially of coffee. The evaluation of this sensory feature is complex yet indispensable in quality control of instant coffees. In this work, an artificial neural network (ANN) was developed for instant coffee classification based on an electronic nose (EN) aroma profile. To this purpose, a hybrid algorithm was developed, containing: bootstrap resample methodology; factorial design and sequential simplex optimization to tune network parameters; an ensemble multilayer perceptron (MLP) trained with backpropagation for coffee classification; and causal index procedure for knowledge extraction from the trained ANN. The produced neural network classifier correctly recognizes 100% of coffees studied. Furthermore, the causal index employment allowed inference of some rules on how the coffees were separated according to the sensors available in EN. The results indicate that the applied methodology is a promising tool for instant coffee quality control.

Avaliação de biocombustível derivado do bio-óleo obtido por pirólise rápida de biomassa lignocelulósica como aditivo para gasolina

A biofuel was prepared from acid aqueous fraction (pH = 2) of bio-oil produced by fast pyrolysis (Bioware Technology) of lignocellulosic biomass (sugar cane residue) and tested in blends (2, 5, 10 e 20% v/v) with gasoline type C (common) marketed in Brazil. The specification tests made in the Refinery President Getulio Vargas (PETROBRAS) showed increasing in the octane number (MON) and antiknock index (AKI) with reduction in the residue generation during the combustion. The physicochemical characteristics of the biofuel were similar that combustible alcohol allowing its use as gasoline additive.

Difusão multicomponente durante a salga mista de queijo prato

A relacao entre o NaCl e a hipertensao arterial tem estimulado a sua substituicao parcial por KCl em queijos. Entretanto, para manter a qualidade final do produto, e de suma importância assegurar uma proporcao adequada de NaCl/KCl, bem como a distribuicao homogenea destes sais. Os modelos que estimam a concentracao salina, portanto, sao valiosas ferramentas para o controle de qualidade. Para simular a difusao multicomponente durante a salga em salmoura estatica, foi proposto um modelo unidimensional, baseado na solucao analitica da 2a lei de Fick generalizada para dois solutos. A solucao analitica, implementada atraves de um algoritmo computacional, permitiu o ajuste dos coeficientes de difusao e a avaliacao da resistencia externa. Os resultados da simulacao obtidos apresentaram boa concordância com os valores experimentais (desvio de 2,7% para o NaCl e 6,6% para o KCl), validando a capacidade preditiva do modelo proposto. Alem disso, a simulacao pode permitir um ajuste de ganhos de produtividade (reducao do tempo de salga) atraves da estimativa do tempo de salga para teores salinos desejados.