The purpose of this study was to evaluate the convective drying process of the watermelon rind and develop flour with technological and nutritional application to human nutrition. The rind was cut longitudinally (5 mm thick), preserving the epicarp and mesocarp, and it was subjected to convective drying under air temperature conditions (40-60 ºC) and with the air speed fixed (1.0m.s-1). Studies of the drying kinetics, mathematical modeling (Fick, Page and Two Parameter Empirical) of the experimental curves and determination of the effective diffusivity, water and moisture activity were conducted as parameters to define the best technological process conditions. Physiochemical characteristics of the watermelon rind flour were determined. The temperature increase resulted in the increase of the water effective diffusivity values, having the Page and Two Parameter Empirical models as those that were better adjusted to the experimental data. Based on the quality responses, 60 ºC was defined as the best condition, resulting in flour with expressive protein content and minerals.

El objetivo fue evaluar el proceso de secado por convección de la corteza de la sandía, y el desarrollo de la harina con aplicación en la nutrición humana. La materia prima se cortó longitudinalmente (5 mm de espesor), preservando el epicarpio y mesocarpio y fue sometida a secado por convección en diferentes condiciones de temperatura del aire (40-60 ºC) y una velocidad fija del aire (1.0 m.s-1). Se llevó a cabo el estudio de la cinética de secado, el ajuste a los modelos matemáticos (Fick, Page y de dos parámetros empíricos),la determinación de las curvas experimentales y de la difusividad efectiva, la actividad del agua y la humedad, como parámetros para definir la mejor condición del proceso tecnológico. Se determinó las características fisicoquímicas de la harina de cáscaras de sandía. El aumento de la temperatura produjo un aumento en los valores de difusividad efectiva de agua y el modelo empírico de los dos parámetros fue el que mejor ajustó a los datos experimentales. La temperatura de 60 ºC se definió como la mejor condición del secado, lo que resulta en la harina con cantidades significativas de proteínas y minerales.

O presente trabalho teve como objetivo a obtenção de isotermas de dessorção de cogumelo Agaricus blazei nas formas in natura e desidratada osmoticamente com solução de NaCl (10% p/p) a 20°C. As isotermas foram determinadas nas temperaturas de 40, 60 e 80°C, através do método gravimétrico estático com soluções salinas saturadas. Os dados experimentais foram ajustados a cinco modelos da literatura (BET, GAB, Halsey, Henderson e Oswin) e a dois modelos com o parâmetro temperatura (Henderson modificado e Chung-Pfost). O desvio relativo médio entre os valores experimentais e os valores preditos foi calculado para cada curva para se avaliar o modelo que apresentou melhor ajuste. Assim, observou-se que os modelos de Henderson e Henderson modificado foram os que melhor se ajustaram dentre as equações sem e com o parâmetro temperatura tanto para o cogumelo in natura quanto para o desidratado osmoticamente.

The present paper aimed at obtaining the desorption isotherms of Agaricus blazei mushroom in nature, which suffered osmotic dehydration. The osmotic treatment was carried out at 20ºC with 10% w/w salt solution. The isotherms were obtained for three different temperatures (40, 60 and 80°C) using the static method with saturated salt solutions. Experimental data were fitted by five models (BET, GAB, Halsey, Henderson and Oswin) and two models with the temperature as an independent variable (modified Henderson and Chung-Pfost). The average relative deviations between experimental and predicted data were obtained to choose the best model. The best fitting was obtained when the traditional and modified Henderson models were used.