EQA - Escola de Química e Alimentos
URI permanente desta comunidadehttps://rihomolog.furg.br/handle/1/1610
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29 resultados
Resultados da Pesquisa
- ItemCaracterização da secagem convectiva de tomate (Lycopersicon Esculentum Mill) em camada delgada(EDGRAF, 2011) Coelho, Karen Dias; Pinto, Luiz Antonio de AlmeidaO trabalho teve como objetivo a caracterização da cinética de secagem do tomate (Lycopersicon esculentum Mill) em camada delgada, e a determinação da reidratação e do teor de licopeno do produto final. O estudo foi realizado em um secador de bandejas com escoamento paralelo do ar, onde as variáveis estudadas foram temperatura do ar de secagem (60, 70 e 80°C) e espessura das amostras (3, 5 e 7 mm). As isotermas de equilíbrio foram determinadas pelo método gravimétrico usando soluções ácidas, e os dados experimentais foram ajustados através da equação de GAB. Nos experimentos de secagem, foi usada a equação de Henderson e Pabis para a obtenção da constante de secagem (K), e os valores de da difusividade efetiva de umidade (DEF) apresentaram-se entre 1,56 a 2,67×10-10 m2 s -1 e entre 4,21 a 8,35×10-11 m 2 s -1, sendo os valores da energia de ativação de 16,99 e 30,64 kJ mol-1, respectivamente, para o primeiro e o segundo períodos de taxa decrescente de secagem. Para a reidratação, verificou-se que com menores temperaturas do ar obteve-se uma maior reidratação do produto num menor tempo, e o teor de licopeno também foi maior nessas condições.
- ItemPolyunsaturated fatty acid concentrates of carp oil: chemical hydrolysis and urea complexation(Springer, 2012) Crexi, Valéria Terra; Monte, Mauricio Legemann; Monte, Maurício Legemann; Pinto, Luiz Antonio de AlmeidaThe aims of this study were to compare three treatments in the chemical hydrolysis reaction of bleached oil from carp (Cyprinus carpio) heads and to obtain polyunsaturated fatty acid concentrates by urea complexation. The three treatments were carried out with different oil:ethanol molar ratios. In the treatment with a 1:39 molar ratio, a higher yield of free fatty acids was found. These fatty acids were submitted to urea complexation (−10 °C for 20 h, and urea–fatty acid ratio of 4.5–1). There was a 31.4% increase in monounsaturated and polyunsaturated fatty acids (MUFA and PUFA) content and a 75% decrease in saturated fatty acids (SAF) content. An increase of 85.4% in the EPA + DHA content was found. The non-urea complexing fraction can be considered a rich source of MUFA and PUFA with a total amount of 88.9%.
- ItemKinetics and mechanism of the food dye FD&C Red 40 adsorption onto chitosan(ACS, 2011) Piccin, Jeferson Steffanello; Dotto, Guilherme Luiz; Vieira, Mery Luiza Garcia; Pinto, Luiz Antonio de AlmeidaThe kinetics and mechanism of the food dye disodium 6-hydroxy-5-((2-methoxy-5-methyl-4-sulfophenyl)azo)-2-naphthalenesulfonate (FD&C Red 40) adsorption onto chitosan were studied. The effects of pH (5.7 to 7.4), chitosan dosage [(250 to 500) mg 3 L 1], deacetylation degree (42 % to 84 %), and particle size [(0.10 to 0.26)mm] were investigated. The adsorption reaction models were used to evaluate the kinetic behavior. Infrared analysis and models based on mass transfer phenomena were used to investigate the adsorption mechanism. The maximum adsorption capacity (300 mg 3 g 1 ) was found at a pH 5.7, chitosan dosage of 250 mg 3 L 1 , deacetylation degree of 84 %, and particle size of 0.10 mm. Pseudosecond-order and Elovich models were the most appropriate to fit the experimental data of adsorption kinetics. The adsorption process was controlled by intraparticle diffusion, film diffusion, or convection according to the experimental conditions. Infrared analysis showed the chemical interaction between chitosan and food dye FD&C Red 40.
- ItemDiffusional mass transfer model for the adsorption of food dyes on chitosan films(Elsevier, 2014) Dotto, Guilherme Luiz; Buriol, Celene; Pinto, Luiz Antonio de AlmeidaThe adsorption kinetics of erythrosine B and indigo carmine on chitosan films was studied by a diffusional mass transfer model. The experimental curves were obtained in batch system under different conditions of stirring rate (80–200 rpm) and initial dye concentration (20–100 mg L−1). For the model development, external mass transfer and intraparticle diffusion steps were considered and the specific simplifications were based on the system characteristics. The proposed diffusional mass transfer model agreed very well with the experimental curves, indicating that the surface diffusion was the rate limiting step. The external mass transfer coefficient (kf) was dependent of the operating conditions and ranged from 1.32 × 10−4 to 2.17 × 10−4 m s−1. The values of surface diffusion coefficient (Ds) increased with the initial dye concentration and were in the range from 0.41 × 10−14 to 22.90 × 10−14 m2 s−1. The Biot number ranged from 17.0 to 478.5, confirming that the intraparticle diffusion due to surface diffusion was the rate limiting step in the adsorption of erythrosine B and indigo carmine on chitosan films.
- ItemProduct characteristics and quality of bovine blood-enriched dried vegetable paste(Wiley Online Library, 2014) Rocha, Silvia Faria da; Rodrigues, Marla; Monte, Micheli Legemann; Larrosa, Ana Paula Quites; Pinto, Luiz Antonio de AlmeidaBACKGROUND: The aim of this study was to evaluate a preparation of vegetable paste with bovine blood in order to maximize the protein content using linear programming, and to analyze the product characteristics and quality of bovine blood-enriched vegetable paste dried in a spouted bed. The drying experiments were performed by evaluating the effects of inlet air temperature, paste flow rate and paste solids concentration on the dried product characteristics and quality (functional and nutritional properties). RESULTS: The vegetable paste enriched with bovine blood was a good source of protein (∼0.20 g g−1, dry basis), and the linear programming was adequate to select the constituents (carrot, onion, potato, kale, tomato, soybean oil and bovine blood) and optimize their quantities. The drying conditions of bovine blood-enriched vegetable paste in the spouted bed that gave the best product characteristics were an air temperature of 110 ∘C and a paste flow rate of 600mL h−1 with 0.07 g g−1 solids concentration. CONCLUSION: The addition of bovine blood to vegetable paste by linear programming increased the protein content of the paste and improved its functional properties and digestibility. The powder obtained from the spouted bed drier showed suitable functional and nutritional properties and was also a good source of antioxidant compounds. © 2014 Society of Chemical Industry.
- ItemApplication of chitosan films for the removal of food dyes from aqueous solutions by adsorption(Elsevier, 2013) Dotto, Guilherme Luiz; Moura, Jaqueline Motta de; Cadaval Junior, Tito Roberto Sant'Anna; Pinto, Luiz Antonio de AlmeidaChitosan films were applied to remove acid red 18 and FD&C blue no. 2 dyes from aqueous solutions. The films were prepared by casting technique and characterized. Batch adsorption equilibrium experiments were carried out at different temperatures (298–328 K). Freundlich, Langmuir and Redlich–Peterson models were fitted to the experimental data. The thermodynamic parameters (ΔG0, ΔH0 and ΔS0) were also estimated. Kinetic study was realized using pseudo-first order, pseudo-second order and Elovich models. The possible films–dyes interactions were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry and color parameters. The maximum experimental adsorption capacities were 194.6 mg g−1 and 154.8 mg g−1 for the acid red 18 and FD&C blue no. 2, respectively, obtained at 298 K. It was found that the Redlich–Peterson isotherm model presented satisfactory fit with the experimental data (R2 > 0.98 and ARE < 9.00%). The adsorption process was spontaneous, favorable, exothermic, and occurred by electrostatic interactions. The Elovich model was the more appropriate to represent the adsorption kinetic data (R2 > 0.95 and ARE < 5.00%). The chitosan films maintained its structure and were easily separated from the liquid phase after the adsorption process.
- ItemMoisture sorption properties of chitosan(Elsevier, 2010) Rosa, Gabriela Silveira; Moraes, Mariana Agostini de; Pinto, Luiz Antonio de AlmeidaThe moisture equilibrium isotherms of chitosan were determined at 20, 30, 40, 50 and 60 °C, using the gravimetric static method. Experimental data were analyzed by the GAB, Oswin, Halsey and Smith equations. Isosteric heat and differential entropy of sorption were determined from the GAB model using the Clausius-Clapeyron and Gibbs-Helmholtz equations, and pore size distribution was calculated by the Kelvin and Halsey equations. The GAB and Oswin equations showed best fit to the experimental data with R2 ≈ 99% and low mean relative deviation values (E% < 10%). Monolayer moisture content values (from 0.12 to 0.20 kg kg−1) and water surface area values (from 450 to 700 m2 g−1) decrease with increasing temperature. Isosteric heat and differential entropy of sorption were estimated as a function of moisture content. The Kelvin and Halsey equations were adequate for calculation of pore size distribution, which varied from 0.5 to 30 nm.
- ItemOptimisation of Spirulina platensis convective drying: evaluation of phycocyanin loss and lipid oxidation(2010) Oliveira, Elisangela Gonçalves de; Duarte, Jéssica; Barros, Kelly Moraes de; Crexi, Valéria Terra; Pinto, Luiz Antonio de AlmeidaThe aim of the study was the optimisation of Spirulina platensis drying on convective hot air through the response surface methodology. The responses were thiobarbituric acid (TBA) and phycocyanin loss percentage values in final product. Experiments were carried out in perforated tray drier with parallel air flow, and the wet samples thickness and drying air temperatures were in range of 3–7 mm and 50–70 °C, respectively. The statistical analysis showed significant effect (P < 0.05) for air temperature and samples thickness. In the best drying condition, 55 °C and 3.7 mm, presented the phycocyanin loss percentage and the TBA values of approximately 37% and 1.5 mgMDA kg−1, respectively. In this drying condition, the fatty acids composition of the microalgae Spirulina did not show significance difference (P > 0.05) in relation to fresh biomass. The lipid profile of dried product presented high percentage of polyunsaturated fatty acids (34.4%), especially the gamma-linolenic acid (20.6%).
- ItemAdsorption of food dyes onto chitosan: Optimization process and kinetic(Elsevier, 2011) Dotto, Guilherme Luiz; Pinto, Luiz Antonio de AlmeidaAdsorption of food dyes acid blue 9 and food yellow 3 onto chitosan was optimized. Chitosan was obtained from shrimp wastes and characterized.Afull factorial design was used to analyze the effects of pH, stirring rate and contact time in adsorption capacity. In the optimal conditions, adsorption kinetics was studied and the experimental data were fitted with three kinetic models. The produced chitosan showed good characteristics for dye adsorption. The optimal conditions were: pH 3, 150rpm and 60 min for acid blue 9 and pH 3, 50rpm and 60 min for food yellow 3. In these conditions, the adsorption capacities values were 210mgg−1 and 295mgg−1 for acid blue 9 and food yellow 3, respectively. The Elovich kinetic model was the best fit for experimental data and it showed the chemical nature of dyes adsorption onto chitosan.
- ItemEvaluation of molar weight and deacetylation degree of chitosan during chitin deacetylation reaction: Used to produce biofilm(Elsevier, 2011) Moura, Catarina Motta de; Moura, Jaqueline Motta de; Soares, Niege Madeira; Pinto, Luiz Antonio de AlmeidaChitosan is a polysaccharide derived from chitin, mainly of crustacean shells and shrimp wastes. The utilization of chitosan is related to the molar weight and deacetylation degree of the biopolymer. The aim of this work is to study the chitin deacetylation reaction, by the viscosity average molar weight and deacetylation degree of chitosan as a function of reaction time. Deacetylation was carried out in concentrated alkaline solution, 421 g L−1, at 130◦C and the reaction occurred during 4 h. Chitosan paste obtained after 20, 90 and 240 min was used to produce biofilms, which were characterized according water vapor permeability and mechanical properties (tensile strength and percentage tensile elongation at break). During the reaction time deacetylation degree reached 93%, and a 50% reduction in the viscosity average molar weight value in relation to the value of the first 20 min of reaction was found Both reactions presented a kinetic behavior of the pseudo-first order. Biofilm produced from the paste of chitosan with high deacetylation degree showed higher water vapor permeability (WVP), tensile strength (TS) and elongation (E) when compared to films with a low deacetylation.
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