Maria Elita Martins Duarte

Caracterização termofísica de polpas de bacuri

SUMMARY THERMOPHYSICAL CHARACTERIZATION OF BACURI PULP. Thermophysical properties, specific heat, density, thermal diffusivity and thermal conductivity of bacuri pulps at different concentrations were studied. The specific heat was determined by the mixture calorimeter method; the density was determined by the pycnometer; the thermal diffusivity was obtained by using the infinite cylinder method; the thermal conductivity was determined from the experimental results obtained for density, specific heat and thermal diffusivity. All the properties were also theoretically determined using proposals equations and regressions. Among the experimental results the specific heat varied from 3.616 to 2.986 kJ/kgoC; the density varied from 1,008.40 to 1,048.36 kg/m 3 ; the thermal diffusivity varied between 1.637x10-7 and 1.787x10-7 m2/s; the thermal conductivity varied from 0.50 to 0.64 W/moC. Except for the density, the value of all the properties decreased, whereas the concentration increased. The thermal conductivity was fitted

Desidratação osmótica de fatias de jaca

The present work was undertaken with the objective of studying the kinetics and the osmotic-dehydration modeling of slices of jack-fruit in a flat layout. The osmotic treatment was carried out at 43oC, employing agitation, and using sucrose solutions at concentrations of 40o and 50o Brix. The study of the kinetics of osmotic dehydration showed that in the sucrose solution at 50o Brix, the value of the water-loss (WL) was higher after 28.5 hours of processing (68.5% wb to 40.2% wb) , slightly higher than that found for the sucrose solution at 40o Brix (68.5% wb to 43% wb). The opposite behavior was observed for the gain in solids (SG). Adjustment of the experimental data was done using the Page and Fick models. From the analysis of the Fick equation, it was found that the effective diffusivity coefficients were 0.5837 and 0.6677 mm2 min-1 for 40o and 50o Brix, respectively.

Determinação do teor de água limite para crioconservação das sementes de ipê amarelo (Tabebuia chrysotrica (Mart. Ex. DC.) Standl.)

Objetivou-se, nesta pesquisa, determinar o teor de agua mais adequado a crioconservacao das sementes de ipe amarelo quando submetidas a armazenagem a temperatura de - 196oC, por cinco dias. Foram preparadas amostras de sementes de ipe amarelo com teores de agua entre 4 e 12%, base umida. Foram realizados testes de germinacao e vigor das sementes antes e depois da crioarmazenagem. O teor de agua limite para a crioconservacao do ipe amarelo e de 4%, base umida.

Modelos de predição da cinética de secagem dos grãos de guandu

The objective of this research was to study the kinetics of the thin-layer drying of pigeon peas subjected to different drying conditions, using different mathematical models. The effective diffusivity and activation energy were determined with the Fick model. For this purpose, 200g samples of pigeon peas with an initial moisture content of 25% (w.b.) were dried in an experimental fixed bed dryer, adjusted to operate at temperatures of 40, 50, 60 and 70 °C, and a drying air rate of 1.0m s–1. For each temperature, drying was continued until the water content reached dynamic equilibrium. The average values for the temperature and relative humidity of the air were, respectively, 26 °C and 68%. For each temperature the effective diffusivity of the product was determined assuming the pigeon pea to be a sphere of equal volume. The effective diffusivity of the product in relation to the temperature was expressed by an equation similar to that proposed by Arrhenius. An analysis of the results allows for the conclusion that the equations of Cavalcanti Mata with six constants and of Midilli et al. satisfactorily represented the drying process under all conditions studied; and that using the Fick model the diffusivity of the pigeon peas ranged from 2.1x10–10 to 6.8x10–10 m2.s–1 at temperatures between 40 and 70 °C, respectively, with an activation energy equal to 34.51 kJ.mol–1.

Difusividade térmica aparente de sementes de cajá em temperaturas acima do congelamento até ultrabaixas temperaturas

The aim of this study was to determine experimentally the apparent thermal diffusivity caja seeds, evaluating the effect of variation of water content and temperature and adjust different mathematical models to experimental values. Seeds with the range of water content from 6.05 to 61.84% (wb) subjected to drying at a temperature of 40 oC were studied. The reduction of water content during drying was monitored by gravimetric method (weight loss). The apparent thermal diffusivity of caja seed was determined by the method of Dickerson. It was concluded that the apparent thermal diffusivity in temperature above freezing and ultralow temperatures as a function of water content (wb), can be satisfactorily represented by a linear regression model and that value of the apparent thermal diffusivity increases exponentially with increasing temperature.

Influence of spray drying conditions on the properties of avocado powder drink

Consumers are increasingly looking for foods with attractive taste, easy preparation, quick consumption and nutritious. Avocado is a nutritional fruit that presents a preservation challenge to food industry. The development of powder blends using spray drying of avocado as a powdered drink is an attractive option that generates products with high nutritional value and stable. Two avocado formulations were spray dried using a design of experiments to assess the influence of drying conditions on powder blends. Results showed higher drying temperatures in combination with smaller droplets resulted in higher yields, lower residual moisture, lower water activity, and in smaller, less dense particles with color green. The inclusion of maltodextrin proved to be vital in preserving high contents of protein, ascorbic acid, and phenolic compounds at any drying conditions possibly due to hydrogen bonding stabilization of those compounds. Using a scalable and efficient drying process, avocado high nutritional value was maintained.

Caracterização tecnológica de cookies produzidos com diferentes concentrações de farinha de algaroba durante armazenamento por 120 dias

This study aimed to assess the quality parameters (water activity, firmness, brittleness and colour) of cookies enriched with different mesquite flour concentrations (5, 15 and 25 g100g-1) during storage for 120 days, and to determine their physical (thickness, diameter, expansion factor, specific volume and mass), physicochemical (water, ash, protein, sugar, fat and fibre contents) and mineral (calcium, phosphorous and iron) characteristics. The quality parameters of these products were monitored for 120 days of storage, with an interval of 15 days between measurements. The physical and physicochemical characterizations were carried out and the minerals quantified using X-ray diffraction spectroscopy by dispersive energy. The quality parameters of the products were statistically analysed using a factorial experimental design with two factors, 9 stoarge periods and three cookie formulations. It was concluded there were significant differences between the quality parameters of the cookies after 120 days of storage. The water activity, brittleness and brightness increased in the cookies elaborated with mesquite flour and the firmness and intensities of yellowness and redness decreased. With the increase in Rennan Pereira de Gusmão1* , Thaisa Abrantes Souza Gusmão1, Henrique Valentim Moura1, Maria Elita Martins Duarte1, Mário Eduardo Rangel Moreira Cavalcanti-Mata1 1 Universidade Federal de Campina Grande (UFCG), Departamento de Engenharia de Alimentos, Campina Grande/PB Brasil *Corresponding Author Rennan Pereira de Gusmão, Universidade Federal de Campina Grande (UFCG), Departamento de Engenharia de Alimentos, Rua Denise Alves de Medeiros, no 60, CEP: 58410-743, Campina Grande/PB – Brasil, e-mail: rennangusmao@gmail.com Cite as: Technological characterization of cookies made with different concentrations of mesquite flour during 120 days of storage. Braz. J. Food Technol., v. 21, e2017116, 2018. Received: July 28, 2017; Approved: Oct. 05, 2017 http://bjft.ital.sp.gov.br 2 Braz. J. Food Technol., Campinas, v. 21, e2017116, 2018 Caracterização tecnológica de cookies produzidos com diferentes concentrações de farinha de algaroba durante armazenamento por 120 dias Gusmão, R. P. et al.

Rheological behavior of mixed drink of annona and milk

In this study the rheological behavior in different temperatures (0; 6; 18 e 24 oC) and physicochemical parameters of integral annona (Annona squamosa) pulp and the annona pulp with milk in different percentages pulp/milk (75g of annona pulp/25g of milk, 50g of annona pulp/50g of milk, 25g of annona pulp/75g of milk) have been availed, in order to verify the effect of temperature and pulp concentration in the rheological behavior of these beverages. To obtain the rheological parameters a concentric cylinder rheometer has been used and the rheograms were analyzed using the Ostwald-de-Wael (power Law) and Herschel-Bulkley models. The physicochemical parameters (sugars, pH, ash, acidity and soluble solids) were determined in order to establish correlations with the rheological behavior. Finally, the best results had been obtained using the Herschel-Bulkley model; the low values for the behavior index (n <1) obtained confirm the pseudoplastic behavior of all samples.