Study on the application of microwaves to the drying of osmotically treated bannanas. / Estudo da aplicação de microondas na secagem de bananas tratadas osmoticamente.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Brasil is one of the largest banana producer in the world, with the crop being predominantly consumed in the internal market, as table in natura fruit and as processed foods. The implementation of methods to transform such a raw material becomes attractive as long as it takes advantage of the production surplus, reduces the crop wastes and allows aggregating value to the raw material. Processing technologies have been developed in order to assure a longer shelf life, an increased process yield and most of all a better quality of the final banana products. As this work relates to the methods of processing banana, it aims at contributing to the adoption of new technologies of obtaining processed products, demonstrating that applying microwaves to drying agricultural products helps to accelerate the kinetics of drying. Furthermore, being the kinetics well controlled, the dried product can reach a quality level comparable or even superior to that obtainable by means of the conventional methods. By applying a combined process of drying using microwaves and hot air, it is possible to evaluate the drying kinetics and the product quality, expressed as color, apparent volume, shrinkage, re-hydration capability and porosity of the dried sample. By studying the influence of microwave power, air temperature and velocity on the two decreasing drying rate periods of the osmo-dehydrated bananas, it was cogitated on the possibility of applying microwaves into separate stages along the drying process, toward reducing the overall processing time. It could be concluded that increasing the applied microwave power resulted in accelerating the kinetics of both the initial and final drying periods. On the other hand, the air temperature showed a secondary effect on the drying operation when the microwaves were incorporated to the process, whereas the air velocity did not exhibit any influence on the drying kinetics. The osmotic dehydration did not affect the drying kinetics, although contributing to reduce the drying times through decreasing the initial moisture and to the advantage of the product quality in terms of visual appearance and shrinkage. In such a manner, this study can be useful to explore the development of accelarated drying processes that conjugate the energy provision to the requirements of the product, aiming to the preservation of its structural characteristics.

ASSUNTO(S)

banana - secagem drying microwaves porosidade osmotic dehydration microondas secagem desidratação osmotica porosity banana

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