Resumo O acuri é uma fruta pouco explorada industrialmente, mas com grandes perspectivas e possibilidades de uso. Para tanto, torna-se necessário reduzir o seu teor de água, aumentando então a sua vida útil, o que possibilitará sua utilização em mercados distantes dos locais de produção. Nesse sentido, objetivou-se secar fatias de acuri, com espessura de aproximadamente 4,07 mm, nas temperaturas de 60, 70, 80 e 90 °C, ajustar diferentes modelos matemáticos aos dados experimentais e determinar os coeficientes de difusão, a energia de ativação e as propriedades termodinâmicas. Observou-se que o aumento de temperatura de 30°C reduziu em 36% o tempo total de processo, sendo obtidas taxas de secagem máximas de 1,22; 1,88; 2,16, e 2,45 kg de água kg de matéria seca min-1 nas temperaturas de 60, 70, 80 e 90 °C, respectivamente. Dentre os modelos matemáticos testados, o modelo logarítmico apresentou os melhores parâmetros de ajustes aos dados experimentais e foi selecionado como o mais adequado para representar o fenômeno investigado. Os coeficientes de difusão efetivos aumentaram com o incremento de temperatura, apresentando-se na ordem de 10-10 m2 s-1 , e sua dependência com a temperatura foi descrita pela Equação de Arrhenius, que apresentou energia de ativação de 17,66 kJ mol-1 . Os valores de entalpia e entropia reduziram com a elevação da temperatura de secagem, enquanto que a energia livre de Gibbs foi ampliada na faixa de temperatura avaliada.

This study aimed to evaluate the effect of drying temperature (50, 60, 70 and 80 °C) on okra dehydration by comparing its powder’s physical properties obtained from a sample produced by a lyophilization process. Ten drying models were adjusted to the experimental data of the drying kinetics. As a result, effective diffusivity and activation energy were determined in addition to thermodynamic parameters: entropy, enthalpy and Gibbs free energy. A physical characterization, as well as the pigments and colorimetry analyses of the aforementioned powders were made, by comparing them with samples produced by lyophilization. The powders were characterized for hygroscopicity, solubility, wettability, apparent and compacted density, fluidity and cohesiveness, pigments, colorimetric, morphological analysis (SEM) and X-ray diffraction. Midilli model was the one that best adjusted to the drying kinetic curves. There was a booster in the effective diffusion coefficient with the increase of temperature. Enthalpy and entropy were reduced with the increase of both drying temperature and Gibbs free energy. The powders presented high luminosity, and the lyophilized powder had higher pigments retention and greater solubility. All powders presented poor fluidity and intermediate cohesiveness, with amorphous, irregular and asymmetric particles. Thus, from the present study it was possible to evaluate the best drying method, the one that should be applied for the drying of okra, considering the costs involved, its quality and the final application of the product, meeting the specific needs of each consumer

The agricultural processing industry is continually working to meet consumer demand for new products, diversifying the supply of non-perishable items ready for consumption, conveniently prepared to maintain the main characteristics of the raw material. The objective of this work was to dehydrate whole okra by lyophilization and convective drying at 50, 60, 70 and 80 °C and to evaluate the influence of drying processes on the chemical and physical quality of powdered products. The powders had acceptable contents of lipids, sugars, proteins, pectin, chlorophyll and carotenoids, high hygroscopicity and low solubility. Lyophilization produced powders with characteristics closer to those of the fresh raw material. Regarding the contents of ashes, pectin, lipids and chlorophyll b, the samples obtained by convective drying showed characteristics close and even superior to those of the lyophilized powder.

One approach to improve sustainable agro-industrial fruit production is to add value to the waste generated in pulp extraction. The processing of cumbeba (Tacinga inamoena) fruits generates a significant amount of waste, which is discarded without further application but can be a source of bioactive compounds, among other nutrients. Among the simplest and most inexpensive forms of processing, convective drying appears as the first option for the commercial utilization of fruit derivatives, but it is essential to understand the properties of mass transfer for the appropriate choice of drying conditions. In this study, cumbeba waste was dried at four temperatures (50, 60, 70 and 80 °C). Three diffusion models were fitted to the experimental data of the different drying conditions. Two boundary conditions on the sample surface were considered: equilibrium condition and convective condition. The simulations were performed simultaneously with the estimation of effective mass diffusivity coefficients (Def) and convective mass transfer coefficients (h). The validation of the models was verified by the agreement between the theoretical prediction (simulation) and the experimental results. The results showed that, for the best model, the effective mass diffusivities were 2.9285 × 10−9, 4.1695 × 10−9, 8.1395 × 10−9 and 1.2754 × 10−8 m2/s, while the convective mass transfer coefficients were 6.4362 × 10−7, 8.7273 × 10−7, 8.9445 × 10−7 and 1.0912 × 10−6 m/s. The coefficients of determination were greater than 0.995 and the chi-squares were lower than 2.2826 × 10−2 for all simulations of the experiments.

This study aimed to dry the pulp of "Biribá" (Rollinia mucosa [Jacq.] Baill) using the foam-mat drying method at the temperatures of 30 C, 40 C, 50 C, and 60 C, fit different mathematical models to the experimental data, calculate the thermodynamic properties, and analyze the powders produced for water activity, morphology, and Xray diffraction. The results showed that the Midilli model, for having the highest coefficients of determination and low values of mean squared deviation and chi-square, could be selected as the most suitable to predict the drying kinetics of "biribá." The effective diffusivity was on the order of 10 À10 m 2 s À1 , and the Arrhenius equation evidenced dependence of this parameter with drying air temperature, which showed an activation energy of 53.47 kJ mol À1 . The thermodynamic properties indicated the existence of an endergonic process. "Biribá" powders showed water activity ranging from .44 to .54 and porous, irregular, and agglomerated morphological structures, with X-ray diffractograms characteristic of amorphous materials. Practical applicationsIn this study, foam-mat drying characteristics of "Biribá" (Rollinia mucosa [Jacq.] Baill) pulp were investigated in a food dehydrator. The effect of different temperatures on drying characteristics and thermodynamic properties, and water activity, microstructural properties and X-ray diffraction of the powders produced was determined. This information may help to optimize the process conditions and reduce costs of processing and packaging.