Isabel Cristina Tessaro
Universidade Federal do Rio Grande do Sul
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Publication
Featured researches published by Isabel Cristina Tessaro.
Journal of Food Science | 2010
Carolina Pereira Kechinski; Pâmela Virgínia Ramos Guimarães; Caciano Pelayo Zapata Noreña; Isabel Cristina Tessaro; Ligia Damasceno Ferreira Marczak
The kinetics of anthocyanin degradation in blueberry juice during thermal treatment at 40, 50, 60, 70, and 80 degrees C were investigated in the present study. Anthocyanin degradation was analyzed up to the level of 50% retention using a pH differential method. The degradation of anthocyanin at each temperature level followed a first-order kinetic model, and the values of half-life time (t(1/2)) at temperatures of 40, 50, 60, 70, and 80 degrees C were found to be 180.5, 42.3, 25.3, 8.6, and 5.1 h, respectively. The activation energy value of the degradation of the 8.9 degrees Brix blueberry juice during heating was 80.4 kJ.mol(-1). The thermodynamic functions of activation (DeltaG, DeltaH, and DeltaS) have been determined as central to understanding blueberry degradation.
Carbohydrate Polymers | 2012
Jordana Corralo Spada; Caciano Pelayo Zapata Noreña; Ligia Damasceno Ferreira Marczak; Isabel Cristina Tessaro
Native and hydrolyzed pinhão starches were used as coating materials for β-carotene microencapsulation by freeze-drying. The purpose of the present study was to evaluate the stability of β-carotene encapsulated under three different conditions: in the presence of ultraviolet light at 25±2 °C, in the dark at 25±2 °C and in the dark at 10.0±0.2 °C. The color of the samples was also analyzed. Microcapsules prepared with native starch showed the lowest stability during storage. In contrast, microcapsules encapsulated with 12 dextrose equivalent (DE) hydrolyzed starch exhibited the highest stability. First-order kinetic and Weibull models were applied to describe the degradation of β-carotene over time. The R(2) values of the Weibull model were greater than those of the first-order kinetic model. Moreover, multivariate analyses (principal component and cluster analyses) were also conducted.
Food Chemistry | 2013
Giovana Domeneghini Mercali; Débora Pez Jaeschke; Isabel Cristina Tessaro; Ligia Damasceno Ferreira Marczak
Degradation kinetics of monomeric anthocyanins in acerola pulp during thermal treatment by ohmic and conventional heating was evaluated at different temperatures (75-90°C). Anthocyanin degradation fitted a first-order reaction model and the rate constants ranged from 5.9 to 19.7 × 10(-3)min(-1). There were no significant differences between the rate constants of the ohmic and the conventional heating processes at all evaluated temperatures. D-Values ranged from 116.7 to 374.5 for ohmic heating and from 134.9 to 390.4 for conventional heating. Values of the free energy of inactivation were within the range of 100.19 and 101.35 kJ mol(-1). The enthalpy of activation presented values between 71.79 and 71.94 kJ mol(-1) and the entropy of activation ranged from -80.15 to -82.63 J mol(-1)K(-1). Both heating technologies showed activation energy of 74.8 kJ mol(-1) and close values for all thermodynamic parameters, indicating similar mechanisms of degradation.
Desalination | 2002
A.F. Viero; A.C.R. Mazzarollo; K. Wada; Isabel Cristina Tessaro
The use of membrane separation process integrated with conventional tannery wastewater treatment was studied in order to reuse the treated effluent in the retanning process. Laboratory scale tests were performed to find a suitable membrane for the process and to define pretreatment, fluid dynamic conditions and membrane cleaning procedures. Hardness levels restrict effluent reutilization on the process. The effects of the addition of lime, soda, Na2CO3 and EDTA to the primary stage of wastewater treatment plant to reduce hardness levels were presented in a previous work. The results obtained are reported and discussed. It was observed that the membrane MX07 (Osmonics) reached hardness retention values of 54%, obtaining soft permeate which is suitable to the process. The permeate will be used in retanning, partially closing the water cycle, and after that, the exhausted baths will be sent to the wastewater treatment plant.
Food Chemistry | 2016
Daiana de Souza; Arthur Francisco Sbardelotto; Denize Righetto Ziegler; Ligia Damasceno Ferreira Marczak; Isabel Cristina Tessaro
This study evaluated the characteristics of rice starch and protein obtained by a fast alkaline extraction method on rice flour (RF) derived from broken rice. The extraction was conducted using 0.18% NaOH at 30°C for 30min followed by centrifugation to separate the starch rich and the protein rich fractions. This fast extraction method allowed to obtain an isoelectric precipitation protein concentrate (IPPC) with 79% protein and a starchy product with low protein content. The amino acid content of IPPC was practically unchanged compared to the protein in RF. The proteins of the IPPC underwent denaturation during extraction and some of the starch suffered the cold gelatinization phenomenon, due to the alkaline treatment. With some modifications, the fast method can be interesting in a technological point of view as it enables process cost reduction and useful ingredients obtention to the food and chemical industries.
Carbohydrate Polymers | 2015
Jordana Corralo Spada; Ligia Damasceno Ferreira Marczak; Isabel Cristina Tessaro; Nilo Sérgio Medeiros Cardozo
This study focuses on the investigation of the interactions between polysaccharides (carrageenan and carboxymethylcellulose--CMC) and soy proteins from the water-soluble soy extract. The influence of pH (2-7) and protein-polysaccharide ratio (5:1-40:1) on the interaction between these polyelectrolytes was investigated in aqueous solutions with 10% of polydextrose and without polydextrose. The studied systems were analyzed in terms of pH-solubility profile of protein, ζ-potential, methylene blue-polysaccharide interactions, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and confocal laser scanning microscopy. Although the mixtures of soy extract with both carrageenan and CMC showed dependency on the pH and protein-polysaccharide ratio, they did not present the same behavior. Both polysaccharides modified the pH-solubility profile of the soy protein, shifting the pH range in which the coacervate is formed to a lower pH region with the decrease of the soy extract-polysaccharide ratio. The samples also presented detectable differences regarding to ζ-potential, DSC, FTIR and microscopy analyses. The complex formation was also detected even in a pH range where both biopolymers were net-negatively charged. The changes promoted by the presence of polydextrose were mainly detected by blue-polysaccharide interactions measures and confocal microscopy.
Food and Bioprocess Technology | 2014
Alan Ambrosi; Nilo Sérgio Medeiros Cardozo; Isabel Cristina Tessaro
Beer is one of the most consumed beverages in the world, placing the brewing sector in a strategic economic position in the food industry. Beer production has a series of physical and chemical steps that are technically intensive when the production scale is increased. Although the production techniques have been improving for hundreds of years, many breweries still employ traditional techniques. The increasing consumption of beer and the competitive market have led the industry to search for alternative technologies to produce a better beer with reduced prices. Membrane separation processes are interesting alternatives that may be utilised in several steps of beer production and may replace some traditional and time-consuming techniques. The objective of this study is to summarise and present a literature survey of the membrane separation processes that are currently applied in the beer industry and those processes that have potential for future applications. The potential of microfiltration, ultrafiltration, reverse osmosis, pervaporation, and gas separation to accomplish almost all solid–liquid–gas separations in a brewery is discussed, providing a clear outline for researchers on the main aspects and developments of the beer-membrane field.
Journal of Agricultural and Food Chemistry | 2014
Giovana Domeneghini Mercali; Steven J. Schwartz; Ligia Damasceno Ferreira Marczak; Isabel Cristina Tessaro; Sudhir K. Sastry
In this work, the influence of the electric field frequency and solids content on the degradation kinetics of ascorbic acid during ohmic heating of acerola pulp and acerola serum was investigated. The degradation percentage of ascorbic acid in the pulp after 120 min of heating varied between 12 and 17%. For the serum, the degradation percentage was in the range of 13 and 18%. The results were fitted to the first-order model, and the kinetic rate constants ranged from 1.1 to 1.6×10(-3) min(-1) and from 1.1 to 1.5×10(-3) min(-1) for pulp and serum, respectively. D values ranged between 1480 and 2145 min for the pulp and between 1524 and 1951 min for the serum. A distinct behavior between the kinetic parameters of the pulp and serum in electric field frequencies ranging from 10 to 1000 Hz indicates that the presence of distinct amounts and types of solids might affect the rate of the electron transfer in electrochemical reactions. These variables may also affect the polarization process stimulated by the oscillating electric field. The non-achievement of the equilibrium of the polarization process may have an influence on oxidation reactions, affecting the predisposition to hydrogen donation from the ascorbic acid molecule.
Separation Science and Technology | 2013
Alan Ambrosi; Isabel Cristina Tessaro
Membrane-based industrial desalination/demineralization plants generate a considerable amount of discarded membranes. This work studies the effects of the chemical treatment with potassium permanganate solutions in combination with chemical cleaning of three years old composite polyamide/polysulfone reverse osmosis membranes (8″ modules) in order to make them reusable in other applications than reverse osmosis and to increase their life cycles. The performance of membranes with 60 cm2 was evaluated in terms of water permeate flux and salt rejection, two properties that can be easily measured in industrial systems. Potassium permanganate treatment degraded the selective layer, improving the water permeate flux of at least 15% from its initial value at the expense of decreased salt rejection. The formation of a manganese oxide layer was detected which reduced subsequent oxidative treatment efficacy. Citric acid was used as a cleaning agent after the oxidation steps, removing part of the manganese oxide layer; the result was an enhanced oxidative process, which increased the permeate flux even more and decreased the loss of salt rejection. Furthermore, to verify the stability of the treatment, the membrane was submitted to a long-term oxidizing experiment.
Brazilian Journal of Chemical Engineering | 2012
C. B. Porciúncula; Nilson Romeu Marcilio; Isabel Cristina Tessaro; M. Gerchmann
The objective of this work is to investigate the production of hydrogen as an energy source by means of the reaction of aluminum with water. This reaction only occurs in the presence of NaOH and KOH, which behave as catalysts. The main advantages of using aluminum for indirect energy storage are: recyclability, non-toxicity and easiness to shape. Alkali concentrations varying from 1 to 3 mol.L-1 were applied to different metallic samples, either foil (0.02 mm thick) or plates (0.5 and 1 mm thick), and reaction temperatures between 295 and 345 K were tested. The results show that the reaction is strongly influenced by temperature, alkali concentration and metal shape. NaOH commonly promotes faster reactions and higher real yields than KOH.
Collaboration
Dive into the Isabel Cristina Tessaro's collaboration.
Ligia Damasceno Ferreira Marczak
Universidade Federal do Rio Grande do Sul
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