CONVECTIVE DRYING OF PINEAPPLE ASSISTED BY HIGH INTENSITY ULTRASOUND

JEFFERSON LUIZ GOMES CORRÊA; MERCEDES CAROLINA RASIA; JOSE VICENTE GARCIA-PEREZ; IMILENA PEREIRA; JUAN ANDRES CÁRCEL

Maceió

Congreso; XXXVI Congresso Brasileiro de Sistemas Particulados; 2013

UNIVERSIDADE FEDERAL DE ALAGOAS

Drying is a unit operation that promotes the conservation of food by reduction of moisture content and water activity. The most used technique of drying is the convective one because it is easy to implement. However, this technique involves the exposure of the food to high temperature for a long time with consequent degradation of quality characteristics as nutrient contents, color and texture. The use of ultrasound in convective drying can improve the process, increasing drying rate by reducing external and internal mass transfer resistances. The goal of this work was to study the influence of the application of ultrasound (75 kW) and the air temperature (40 and 70 °C) on convective drying of slices of pineapples (2.8 cm diameter, 0.5 cm thickness). The air velocity and final moisture content were kept constant, at 1.0 ms-1 and 0.19 kg H20 kg dry matter-1, respectively. The experimental system is totally monitored with the measurement of the mass samples each 5 minutes. Drying time was improved by the application of ultrasound. The temperatures of drying also affected the kinetics. The experimental data were modeled by the use of a diffusive model. The differences between the moisture diffusivity allowed to quantify both temperature and ultrasound influence.