Josivanda Palmeira Gomes

Diffusion Models to Describe the Drying Process of Peeled Bananas: Optimization and Simulation

This article aims to study the mass transient diffusion in solids with a cylindrical shape. To this end, the one-dimensional diffusion equation was discretized using the finite volume method with a fully implicit formulation. The solution can be used to simulate diffusive processes and to determine thermophysical parameters via optimization techniques. The computational package developed was applied to study the thin-layer drying of peeled bananas. Three models were used to describe the drying process: (1) the volume V and the effective mass diffusivity D are considered constant; (2) variable V and constant D; (3) V and D are considered variable. For all models, the convective mass transfer coefficient h is considered constant. The statistical indicators show that for the two cases analyzed (low and high temperature), model 3 describes the drying process better than the other models.

Efeitos de extratos alcoólicos de plantas sobre o caruncho do feijão vigna (Callosobruchus maculatus)

Atraves de tres metodos, extratos vegetais foram aplicados, ao Callosobruchus maculatus na fase adulta, inoculados ou nao em uma massa de sementes, e na fase imatura (ovo) com o objetivo de se controlar esta praga do feijao armazenado. Utilizaram-se flores, folhas, frutos e caule secos de oito especies vegetais na obtencao dos extratos, em percolador, com solvente alcool etilico (70%). O delineamento experimental utilizado foi o inteiramente ao acaso, com os tratamentos distribuidos em esquema fatorial, cujos fatores quantitativos foram revelados pela regressao na analise de variância. Mediante os resultados obtidos, concluiu-se que a mortalidade dos insetos esta relacionada com o tipo de extrato, os metodos de aplicacao e com a dosagem aplicada, sendo os extratos de Callopogonium caeruleum e Piper nigrum os mais eficientes no controle do caruncho de feijao.

Adsorption isotherms of the dry cashew apple

Water activity is a very important factor in a solid state fermentation process due to its relation with the water quantity available to the microorganism that will synthesize the product. Therefore, it is necessary to obtain the sorption isotherms for the characterization of the substrate. The objective of this study is to obtain adsorption isotherms of the dry cashew apple (Anacardium occidentale L.) at normal temperatures of fermentation process (25, 30, 35 e 40 oC). Five mathematical models were fitted to the experimental data: BET, GAB, Oswin, Henderson e Smith. The GAB model was better fitted to the product. The isotherms allowed the determination of the appropriate moisture content to obtain the water activities that maximize the biosynthesis of the microorganism for the pectin production by solid state fermentation process. The moisture content of the substrate should be above 35% d.b.

Effective diffusivity and convective mass transfer coefficient during the drying of bananas

Neste artigo, e usada uma metodologia para a determinacao simultânea da difusividade efetiva e do coeficiente de transferencia convectivo de massa em solidos porosos que possam ser considerados como um cilindro infinito, durante sua secagem. Dois modelos sao utilizados para a otimizacao e a simulacao do processo de secagem: o modelo 1 (volume e difusividade constantes, com condicao de contorno de equilibrio); e o modelo 2 (volume e difusividade constantes, com condicao de contorno convectiva). Algoritmos de otimizacao por varredura, baseados no metodo inverso, foram acoplados as solucoes analiticas referentes aos dois modelos utilizados, possibilitando ajustar tais solucoes aos dados experimentais da cinetica de secagem em camada fina de produtos com a forma cilindrica. Foi feita uma aplicacao da metodologia de otimizacao na descricao da cinetica de secagem de bananas inteiras, usando dados experimentais disponiveis na literatura. Os indicadores estatisticos relativos aos ajustes possibilitam afirmar que a solucao da equacao de difusao com condicao de contorno convectiva produz resultados significativamente melhores que aqueles considerando a condicao de contorno de equilibrio.In this article, a methodology is used for the simultaneous determination of the effective diffusivity and the convective mass transfer coefficient in porous solids, which can be considered as an infinite cylinder during drying. Two models are used for optimization and drying simulation: model 1 (constant volume and diffusivity, with equilibrium boundary condition), and model 2 (constant volume and diffusivity with convective boundary condition). Optimization algorithms based on the inverse method were coupled to the analytical solutions, and these solutions can be adjusted to experimental data of the drying kinetics. An application of optimization methodology was made to describe the drying kinetics of whole bananas, using experimental data available in the literature. The statistical indicators enable to affirm that the solution of diffusion equation with convective boundary condition generates results superior than those with the equilibrium boundary condition.

Isotermas de dessorção da casca do maracujá (Passiflora edulis Sims): determinação experimental e avaliação de modelos matemáticos

The microbial protein production on passion fruit peel shell as an animal protein supplement production is an alternative found out to avoid the large wastage of agri-industrial residues. Through the desorption isotherms of passion fruit peel, it is verified that for the microorganism growth by solidstate fermentation on this residue, the initial moisture content condition should be above 55% (wet basis). The ideal moisture content range for residue storage is around 5.3% (wet basis).

Cinética de secagem do resíduo de abacaxi enriquecido

O Brasil e um dos maiores produtores de abacaxi do mundo e o maior da America do Sul. O fruto e a parte comercializavel da planta enquanto o restante e formado por caule, folha, casca, coroa e talos, considerado residuo agricola e nao tem sido devidamente aproveitado, resultando em perdas economicas. Caracterizar e avaliar a cinetica de secagem do residuo (casca) de abacaxi (Ananas comosus L.) enriquecido utilizando a levedura Saccharomyces cerevisiae em leito estatico, em camada fina de secagem, utilizando-se de planejamento experimental fatorial, foi o objetivo deste estudo. A temperatura (40 a 60 oC) e a velocidade do ar de secagem (0,8 a 1,3 m s-1) sao as variaveis do processo. O residuo enriquecido e caracterizado apresentou alto teor de materia seca (90,27%) e elevado teor de proteina (20,21%) em relacao ao residuo in natura (7,61%). A cinetica de secagem ocorreu no periodo de taxa decrescente. Os modelos Page, Henderson & Pabis e Lewis, ajustaram os dados experimentais satisfatoriamente, sendo Page discretamente superior aos demais. Verificou-se influencia da variavel temperatura apenas para a variavel resposta umidade, nao sendo observada influencia estatisticamente significativa da velocidade do ar de secagem.

Micropropagation of pineapple, cv. Emepa 1

This work aimed to develop a micropropagation protocol of pineapple cv. Emepa 1. The cv. Emepa 1 axillary gems used were disinfested and inoculated in half MS solid with 5.8 pH. There was incubation in a growth room with temperature of 25 ± 5 °C and photoperiod of 16 h light at a luminous intensity of 30 mmol m-2 s-1. The cv. Emepa 1 micropropagation protocol was developed according to the existing literature, comprising the following phases: establishing of explants (EE); multiplication (MU); extent rooting (EN). A completely randomized design (CRD) was used in all the phases as follows: EE - DIC with 6 treatments comprised of 10 repetitions containing 1 explants per bottle; MU - CRD with 8 treatments, comprised of 10 repetitions containing 1 explants per bottle. It was concluded that the concentration of 2% of sodium hypochlorite for 10 min causes gems disinfestations and the establishment can be carried out by means of tillage without any growth regulators. The etiolating can be achieved in MS with 1.86 mg L-1 of ANA and regeneration in MS with 1.8 mg L-1 of the ANa+ 2.0 mg L-1 of BAP. For the multiplication, the type of tillage indicated is MS supplemented with 2.0 mg L-1 of BAP + 0.5 mg L-1 of ANA; in extent, the type of crop MS without any dilution causes the highest growth of seedlings whereas the addition of ANA prompts an increase in number and a decrease of seedlings root size and the organic compound favors an increase and development of pineapple seedlings produced in vitro during the acclimatizing phase.

DRYING KINETICS OF CORIANDER (Coriandrum sativum) LEAF AND STEM CINÉTICAS DE SECADO DE HOJA Y TALLO DE CILANTRO (Coriandrum sativum)

Abstract The drying kinetics of coriander leaves and stems, with or without blanching, was studied at several temperatures (50, 60, 70, and 80°C) at constant air velocity (1.5 m s−1) in a fixed-bed dryer. Three drying models, Henderson and Pabis, Midilli et al., and the Logarithmic, were fitted to the experimental data. According to the results obtained, it was verified that the increase in the temperature of drying air, increases the drying rate of the coriander leaf and stem. Blanching used as a pre-treatment favors the increase in the drying rate of the stem. The Midilli et al. drying model was found to satisfactorily describe the air-drying curves of coriander leaves and stems. Resumen La cinética del secado de las hojas y tallos de cilantro, con o sin escaldado, se estudió a diferentes temperaturas (50, 60, 70 y 80°C) con velocidad constante del aire (1,5 m s−1) en un secador de lecho fijo. Tres modelos matemáticos: Pabis y Henderson, Midilli et al., y el logarítmico, se ajustaron a los datos experimentales. De acuerdo a los resultados obtenidos, se comprobó que el aumento de la temperatura del aire de secado, aumentó la velocidad de secado de la hoja y tallo de cilantro. El escaldado utilizado como pre-tratamiento, favorece el aumento en la velocidad de secado del tallo. El modelo matemático de Midilli et al. presentó mejor ajuste para los datos experimetales. Palabras clave: Pretratamiento, Coriandrum sativum, escaldado, deshidratacíon

Isotermas de sorção do resíduo agroindustrial de casca do abacaxi (Ananas comosus L. Mer)

In the study of the protein enrichment process of ring pineapple (Ananas comosus L. Mer) through the yeast Saccharomyces cerevisiae and Aspergillus niger in solid state fermentation, the water activity is one of the variables that most affects the fermentation process as well as the storage of this enriched protein. The present work, had the objective of obtaing sorption isotherms of the pineapple peel residue in the usual temperatures of the fermentation processes, 25, 30, 35 and 40 oC, in order to correlate water activity and moisture content. The obtained isotherms were analyzed by the models of Henderson and GAB, being the GAB model, in general, the one that better adjusted to experimental data. The isotherms allowed to find appropriate moisture content to obtain the water activities recommended for the fermentation process as well as during the storage of this enriched protein.

Qualidade da semente e fibra de algodão na caracterização do descaroçador de 25 serras 1

A B S T R A C T The cotton is one of the most important crop in the fiber group due to its volume and valued production. This study was conducted with the aim to characterize a ginner regarding physical and physiological quality of seeds and some technological qualities of the cotton fiber. The ginner was made with the following components: cleaner, cylinder saws, cylinder brushes, condenser, and a three-phase electric motor of 3 CV to turn on the equipment. The experimental design was a completely randomized factorial (2 x 2 x 2 x 4), with two cotton cultivars (BRS 187 and BRS Safira 8H), two types of saws (11¾” and 12”), two cleaning process (with and without cleaner) and four rotations (500, 550, 600 and 650 rpm) and four replications. During the processing of seeds, types of saws and cleaning processes did not affect the physical and physiological quality of seeds. Meanwhile, in the technological characteristics of the cotton fiber, the ginner showed efficient performance with the rotation of 550 rpm, using the 12” saws and cleaning device turned activated (cleaner). Palavras-chave: beneficiamento qualidade de sementes qualidade de fibras