Desidratação osmótica com secagem complementar de banana pacovan.

Abstract

This research was conducted in order to study the kinetics of osmotic dehydration and drying processes used for the preparation of dried banana Pacovan and evaluate the processed product for several aspects such as the chemical, physico-chemical and texture, depending on the process variables, temperature and sucrose concentration. The osmotic dehydration process was carried out with three concentrations of sucrose (40, 55 and 70ºBrix ) and three temperatures (50, 60 and 70ºC). From osmotic dehydration resulted 9 products, which were subjected to a complement drying at three temperatures (40, 50 and 60ºC) in a fruit dehydrator with trays and without air circulation. Data from osmotic dehydration and drying were adjusted to three models: Fick , Page and Cavalcanti Mata, using nonlinear regressions and the Statistica 8.0 software; the analysis of water loss and solid gain by osmotic dehydration, was made through analysis of variance, ANOVA, with comparison of averages by the Tukey Test. The products resulting from this process were subjected to chemical and physico-chemical testing (water content, acidity, reducing sugars, pH, total soluble solids, ash, water activity) according to the methodology of the Adolfo Lutz Institute; minerals content ( K , Ca , P , Mg , Fe ), were determined using X-ray spectrometry and texture evaluation using a texturometer TAXTplus performed through rupture of fibers and strength tests. Among the key findings it is concluded that: the sucrose concentration of the osmotic solution, process temperature as well as the interaction between these two factors exert influence on water loss and solid gain in the dehydration process; the model that best represents the experimental data for osmotic dehydration of banana Pacovan is the Page, with coefficients of determination greater than 90%, the diffusion coefficients calculated by the Fick model for osmotic dehydration, are between 1,692 x 10-11 and 8,692 x 10- 11 m2.s-1 for dehydrated bananas at 50ºC in 40oBrix solution and 70ºC in 70oBrix solution, respectively; in complement drying, all tested models satisfactorily represent the experimental data: the diffusion coefficients calculated by the Fick model to complement drying were between 3.49 x 10-10, for the dehydrated banana in 40oBrix solution at a temperature of 50ºC, with complement drying at 40ºC, and 4,38 x 10-8 for the dehydrated banana in 70ºBrix solution at a temperature of 70oC with complement drying at 60ºC; acidity, reducing sugars, total soluble solids and ash content in the osmotic dehydration increased with increasing sucrose concentration; the minerals contente present in greater quantities in processed banana are potassium, calcium, manganese, phosphorus and iron; bananas treated osmotically require greater effort for fiber breakage as it increases the solids content of the desiccant solution in the osmotic dehydration.