Effect of process variables on the osmotic dehydration of star-fruit slices

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The objective of this work was to study the effect of blanching and the influence of temperature, solution concentration, and the initial fruit:solution ratio on the osmotic dehydration of star-fruit slices. For blanching, different concentrations of citric and ascorbic acids were studied. The samples immersed in 0.75% citric acid presented little variation in color in relation to the fresh star-fruit. Osmotic dehydration was carried out in an incubator with orbital shaking, controlled temperature, and constant shaking at 120 rpm. The influence of process variables was studied in trials defined by a complete 2(3) central composite design. In general, water loss and solids gain were positively influenced by temperature and by solution concentration. Nevertheless, lower temperatures reduced water loss throughout the osmotic dehydration process. An increase in the amount of dehydrating solution (initial fruit:solution ratio) slightly influenced the evaluated responses. The process carried out at 50 degrees C with a solution concentration of 50% resulted in a product with lower solids gain and greater water loss. Under these conditions, blanching minimized the effect of the osmotic treatment on star-fruit browning, and therefore the blanched fruits showed little variation in color in relation to the fresh fruit.322357365SAE (Servico de Apoio ao Estudante - UNICAMP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Evaluation of edible films and coatings formulated with cassava starch, glycerol, carnauba wax and stearic acid

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This study aimed at characterizing four formulations of cassava starch, glycerol, carnauba wax and stearic acid-based edible coatings/films, evaluating their water vapor resistance, the respiration rate of coated apple slices, surface solid density, solubility, mechanical properties, thermal properties and microstructure. Among the formulations evaluated, only the formulation with higher wax content did not promote an effective barrier to oxygen and water vapor and resulted in more rigid films. Formulations with higher glycerol content promoted lower respiration rate of apple slices, good water vapor resistance and flexible films, but the microstructure analysis showed a non-homogenous surface of the films with higher wax content. The glycerol added in formulations increased the solubility and reduced the melting temperature of the films. Formulation with 0.2% carnauba wax showed intermediate values of analyzed properties and promoted films with a more regular surface. Formulation containing 3% (w/w) cassava starch, 1.5% (w/w) glycerol, 0.2% (w/w) carnauba wax and 0.8% (w/w) stearic acid, presented films with a cohesive matrix, resulting in better mechanical properties, barrier to moisture and gas exchange. (C) 2013 Elsevier Ltd. All rights reserved.382027Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [08/553431, 09/51420-4

Antioxidant activity and polyphenol contents in Brazilian green propolis extracts prepared with the use of ethanol and water as solvents in different pH values

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Propolis is a natural product with a variable and complex chemical composition associated with its high concentration on polyphenolic compounds. The effect of pH variation (2.0, 3.0, 4.3, 6.0 and 8.0) during aqueous and ethanolic propolis extraction was studied for up to 10 days. Total phenols and flavonoids contents were measured for the extracts by spectrophotometric assays. Antioxidant activity was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and ferric thiocyanate (FTC) methods. The best time of extraction was up to 5 days for all samples. Basic aqueous extracts (pH 8.0) resulted in a higher concentration of compounds than the extract without pH modification, reaching an increase of 160% in flavonoids and 25% in phenols. Ethanolic extracts with pH variation resulted in an extract with 50% less polyphenols and 6% less flavonoids than extract without pH modification. The antioxidant activity was highest for ethanolic extract at pH 4.3 and aqueous extract at pH 8.0 almost 90% and 45%, respectively, in DPPH method and was related to the level of polyphenols by Pearson's correlations.471225102518Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CNPq [141767/2008-1]FAPESP [09/50593-2

Evaluation of the mechanical properties and diffusion coefficients of osmodehydrated melon cubes

The objective of this work was to evaluate the influence of osmotic agents, their concentration and temperature, on the mass transfer kinetics and mechanical properties of osmodehydrated melon cubes. Samples were immersed in a hypertonic solution of sucrose or maltose up to 8 h under controlled temperature and agitation. Water loss, sugar gain and mechanical properties were analysed throughout the process. Mass transfer kinetics was modelled according to Peleg and Fick equations. Higher water loss, lower sugar uptake and stress at rupture values more similar to fresh fruit were observed in samples treated with maltose solutions. Peleg's model showed the best adjustment to all the experimental data, however the k(1) and k(2) parameters did not show a clear trend with the solution concentration or temperature increase. The effective diffusivity obtained using Fick's equation varied from 3.93 x 10(-9) to 6.45 x 10(-9)m(2) s(-1) for water loss and from 7.57 x 10(-10) to 3.14 x 10(-9)m(2) s(-1) for sugar gain.43112065207

Stability, solubility, mechanical and barrier properties of cassava starch - Carnauba wax edible coatings to preserve fresh-cut apples

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This work aimed at evaluating edible coatings/films formulated with cassava starch, glycerol, carnauba wax and stearic acid, analyzing the stability of emulsion (creaming index and lipid particle size), the barrier properties of coatings applied in fresh-cut apples (respiration rate and water vapor resistance), the solubility and mechanical properties of films prepared with coating solutions. A central composite rotatable design 2(3) was used to select optimized formulation. Independent variables used were: cassava starch concentration (2-4% w/w), glycerol content (1-3% w/w) and carnauba wax: stearic acid ratio (0.0: 0.0-0.4: 0.6% w/w). The creaming index and the lipid particle size of emulsified coatings were strongly affected by the carnauba wax: fatty acid ratio. Glycerol content was the variable that most influenced the respiration rate of coated apple slices, water vapor resistance of coatings and the elastic modulus of films. The water solubility was positively affected by the cassava starch and glycerol contents. Models and response surfaces were obtained for the respiration rate, water vapor resistance of coatings, elastic modulus and solubility of films. According to statistical analysis results, the optimized conditions corresponded to 3.0 g of cassava starch/100 g of coating solution, 1.5 g of glycerol/100 g of coating solution, 0.2:0.8 g of carnauba wax: stearic acid ratio/100 g of coating solution. The models obtained in the experimental design were predictive, which was evidenced by the relative deviations below 10% in validation procedure. (C) 2011 Elsevier Ltd. All rights reserved.2815967Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [08/55343-1, 09/51420-4

Thermal transitions of osmotically dehydrated tomato by modulated temperature differential scanning calorimetry

Modulated temperature differential scanning calorimetry (MTDSC) was employed to examine thermal transitions of osmotically dehydrated tomato (Lycopersicon esculentum, var. Deborah). Tomato halves, soaked in sucrose solution (60% sucrose), sodium chloride (10% NaCl) and mixtures of salt-sucrose solution (60% sucrose-10% NaCl/40% sucrose-15% NaCl) for 3 h at 40 degreesC, were comminuted, freeze-dried for 48 It and kept in desiccator over saturated salt solutions at 25 degreesC until equilibrium was reached. A MTDSC 2920 (TA Instruments) was used in all tests. A cyclic modulation of +/- 0.5 degreesC/40 s was superimposed on a constant scanning ramp of 2.5 degreesC/min. Thermo-analytical curves of both osmotically dehydrated and untreated tomato allowed the determination of the glass transition data and the plot of state diagrams. Furthermore, a peak of enthalpy relaxation in the glass transition region that partially disappears on rescanning was detected. Structural recovery was modelled by Williams-Watts equation and glass transition temperature by Gordon and Taylor and Kwei equations. (C) 2002 Elsevier Science B.V. All tights reserved.3954167123724

Influence of process conditions on the physicochemical properties of acai (Euterpe oleraceae Mart.) powder produced by spray drying

The objective of this work was to study the influence of spray drying conditions on the physicochemical properties of acai powder. The process was carried out on a mini spray dryer and maltodextrin 10DE was used as carrier agent. Seventeen tests were made, according to a central composite design. Independent variables were: inlet air temperature (138-202 degrees C), feed flow rate (5-25 g/min) and maltodextrin concentration (10-30%). Moisture content, hygroscopicity, process yield and anthocyanin retention were analysed as responses. Powder moisture content and process yield were positively affected by inlet air temperature and negatively affected by feed flow rate, which are directly related to heat and mass transfer. Process yield was also negatively influenced by maltodextrin concentration, due to the increase on mixture viscosity. Powders hygroscopicity decreased with increasing maltodextrin concentration, decreasing temperature and increasing feed flow rate. Powders with lower moisture content were more hygroscopic, which is related to the greater water concentration gradient between the product and the surrounding air. Anthocyanin retention was only affected by temperature, due to its high sensitivity. In respect to morphology, the particles produced at higher temperature were larger and a great number of them showed smooth surface. (C) 2008 Elsevier Ltd. All rights reserved.88341141

Optimisation of osmotic dehydration process of guavas by response surface methodology and desirability function

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Response surface methodology was used to assess the effects of osmotic solution concentration (4060 degrees Brix), process temperature (2040 degrees C) and vacuum pulse application time (020 min) at 100 mbar on water loss (WL), weight reduction (WR), solid gain (SG), water activity (aw), colour parameters and mechanical properties of guava slices. Optimal process conditions were determined through the desirability function approach and quality characteristics of osmotically dehydrated guavas were analysed. Only models obtained for WL, WR and aw were suitable to describe the experimental data. The desirability function showed that optimal conditions for osmotic dehydration of guavas were: osmotic solution concentration at 60 degrees Brix, process temperature at 32 degrees C and 20 min of vacuum pulse application. Under optimal conditions, colour and mechanical properties of treated guavas were similar to fresh fruit, presenting WL of 29.01 g/100 g, WR of 25.91 g/100 g, SG of 3.10 g/100 g and aw of 0.979.471132140Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [2009/50591-0

Glass transition phenomenon on shrinkage of papaya during convective drying

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)A differential scanning calorimeter was used to determine the T-g of papaya pieces equilibrated with several water activities. Thermograms revealed the existence of two T-g. The first, which presented lower value, is due to the matrix formed by sugar and water. The second one, less visible and less plasticized by water, probably corresponds to macromolecules. The data of T-g were satisfactory correlated by the Gordon-Taylor model. A convective tray dryer was used for the drying experiments, which were carried Out at air temperatures of 40 degrees C and 70 degrees C and air velocity of 1.0 m/s. The shrinkage behavior was accomplished by total area and apparent volume alterations along drying. Samples were photographed during process, and their length and lateral areas were measured using the lrnageJ (R) software. As result, the effect of air temperature on shrinkage was significant and the highest temperature (70 degrees C) induced higher extent of shrinkage values. At this condition, papaya sample was in a rubbery state, characterized by great matrix mobility, and remained so until the end of process, since product temperature (T-p) was above the T-g along the process. At lower temperature (40 degrees C), shrinkage stopped at a critical value of moisture content (0.21 g/g, wet basis), which coincided with the point in which the T-g was close to T-p. (C) 2011 Elsevier Ltd. All rights reserved.10814350Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Effect of Pulsed Vacuum Treatment on Mass Transfer and Mechanical Properties during Osmotic Dehydration of Pineapple Slices

The influence of operating pressure during osmotic dehydration on mass transfer and mechanical properties in pineapple fruits was analyzed. Dehydration trials were performed at atmospheric pressure (OD) and by applying a vacuum pulse (VPOD), in sucrose solution at 60 degrees Brix and 40 degrees C for 300 min. Seven operation conditions were implemented with a vacuum pulse of 100 mbar or 250 mbar for 0, 5, 15 or 25 min at the beginning of the process. The decrease of pressure favored the solute uptake, but the water loss has not been significantly affected. No significant effect of vacuum time was observed. However, solute uptake in trials with vacuum pulse of 100 mbar was significantly higher than in OD process. In general, mechanical properties and shrinkage were not affected by operation conditions. Osmotic dehydration process (both OD and VPOD) originates a more resistant tissue structure than the one in fresh pineapple fruit.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.9440341