Estudo da transferência de calor e massa na secagem em leito fixo visando o aproveitamento de resíduo de acerola (Malpighia Emarginata DC)

Abstract

Nowadays the use of solid wastes is an issue which results in reducing environmental impacts. From acerola fruit processing is estimated that about 40% of the amount sent to industry is discarded as waste. Drying is a unit operation capable of reducing the humidity content of the material, reducing microbial activity, and thus increasing its lifetime in shelf. Among the various types of dryers has highlighted the fixed bed dryer for use in food products. In this work was performed the characterization of acerola waste, the results showed that the fruit possesses antioxidant compounds which enable its drying. With the drying of the acerola waste in thin layer it is possible to observe that the speed and the air temperature may significantly influence the potential drying. Was obtained an equation from drying kinetics as a function of the studied variables. Desorption isotherms of the acerola waste were performed in temperatures of 35, 50, 65 and 80°C through the static method. The Sigma-Copace model fitted better to the experimental data. It was carried out the drying of the acerola waste thick layer and evaluated the influence of air velocity, air temperature and drying time in the drying potential, as well as the content of bioactive compounds by using a orthogonal central composite design. Modeling the experimental data obtained from the fixed-bed drying was performed on thick layer. Finally, was performed the chemical analysis by nuclear magnetic resonance in order to identify other chemical compounds present in the material studied. The drying condition obtained allowed the homogeneity of the waste in relation to the moisture content in all axial positions sampled and with an average content of bioactive compounds evaluated. It was also observed that the levels of bioactive compounds were higher in some drying conditions at dried acerola waste, compared to the levels obtained for the acerola waste in natura. Through chemical analysis were identified as major compounds in acerola waste in natura and dry, the malic acid, two phytosterols, sugars and was not found any anti-feeding compound. Finally, we obtained a product based on the dry residue acerola observed good acceptance from a sensory analysis. Therefore, the use of acerola waste is feasible, and may be inserted in diet in the form of by-products assisting in the prevention and fight against diseases.