The present study aimed to assess the drying kinetics of black rice and fit different mathematical models (empirical and diffusive) to the experimental data, and evaluate the effect of drying air temperature on the physical-chemical and bioactive compounds quality of black rice. Drying air temperatures ranged from 40 to 80 ºC and the drying air speed was 1.5 m/s. Physical-chemical characterization of the product was based on the following parameters: moisture, water activity, ashes, total protein content, pH, total acidity, lipids, total carbohydrates, total anthocyanins, flavonoids, total phenolic compounds and antioxidant activity. Among the empirical models, Page showed the lowest mean squared deviations (MSD) and highest coefficients of determination (R2). For the diffusion model, the values of effective mass diffusivity and convective heat transfer coefficient increased with increasing drying air temperature, and the Biot number indicated that the first-type boundary condition would also describe well the drying process. Physical-chemical parameters and bioactive compounds differed between the temperatures used, and the temperature of 60 ºC led to the best relationship between drying time and preservation of product characteristics.

This study aimed to develop red rice flours in order to provide alternatives to replace conventional flours in the production of gluten-free foods for people who suffers from celiac disease. To obtain the flour, red rice grains were dried at temperatures of 40, 50, 60, 70, and 80 C and air velocity of 1.5 m/s. Mathematical models (empirical and diffusive) were fitted to the experimental data obtained and, subsequently, the dehydrated grains were ground to obtain the flour, which was subjected to physicochemical and bioactive characterization to verify the impact of the applied temperatures on the final product quality. It was found that the Page model is more reliable to describe the drying kinetics of red rice, since it showed higher coefficients of determination (R 2) and lower chi-square (χ 2). The diffusion model showed satisfactory fit, with coefficient of determination (R 2) higher than 0.99 and chi-square (χ 2) lower than 0.0146659. Higher drying rate was found at the temperature of 80 C, but cracks were observed in the grains and there was greater degradation of anthocyanins. The pH, total titratable acidity, and flavonoids did not differ between the temperatures applied. Lower values of moisture content, water activity, total phenolic compounds, and antioxidant activity were obtained in the grains subjected to temperature of 80 C. Therefore, the temperature of 40 C was the one that ensured greatest conservation of all bioactive compounds analyzed and greater antioxidant activity for all three methods. Practical applications: The diffusion model provides a realistic and physical interpretation of the drying operation, stimulating the correct time needed to reduce the moisture content of the material, of initial value at the equilibrium value. In this way, it is possible to save energy and reduce the degradation of bioactive compounds promoted by thermal damage, which material is submitted, in addition to aiming at the optimization of drying equipment projects. 1 | INTRODUCTION Rice (Oryza sativa L.) has several types of cultivars and is a widely consumed food in the world, with different colors, such as white, black, red, and brown. Red rice is thus called because of the reddish color of the pericarp of the grains, which in turn is due to the accumulation of tannins and anthocyanins (Agostineto, Fleck, Rizzardi,

No abstract

Article AbstractVery little information is found about the 'Cambui' products and the fruit is almost unexplored by the Brazilian agriculture or extractive activities. The present study aimed to characterize the physicochemical composition and antioxidant capacity of the juice, jam and fermented beverage obtained from 'Cambuí' fruits aiming to add value to the fruit and generate alternatives to Brazilian extractive population. These products were elaborated in small scale of production. The 'Cambuí' juice was prepared using the method of steam distillation and the jam was obtained from the residue of the juice with addition of sugar and citric acid. The 'Cambuí' fermented beverage was elaborated using procedures of winemaking. For the evaluation of the products quality, chemical analysis and evaluation of the antioxidant capacity were performed.All products presented high concentrations of the studied variables, when comparing to grape wines, fruit jams and grape juices. The 'Cambui' products can be considered sources of antocyanins and other phenolic compounds, with high antioxidant potential. The use of 'Cambui' has potential for the development of juice, jam and fermented beverage, and these products can be an alternative to add value to fruit and generate income for populations that work with which income depend on extractive activities.

No abstract