Secagem de vagens de algaroba Prosopis juliflora (S.w.) DC. em laboratório e a nível de fazenda.

Abstract

This work had as objectives to determine the curves of drying and balance of humidity of foods of algaroba prosopis juliflora (S.W) D.C, In order to get its point of triturating so that it can be employed in the production of animal ration. The foods of algarroba having an initial humidity content of 20% h.b., were submitted to three distinct kinds of drying. In the first one, carried out in lab, foods of algarroba were dried in a dryer with a fixed bottom, in which the height of the layer (25, 20,15 and a thin layer), the air speed (0.6 and 1.5 m.s"1 ) and the temperature of drying (80, 90 and 100°C) until the humidity of triturating (± 7% h.b.) were varied. In the second one the pods were dried in a convective dryer installed at "Cooperativa Agricola Mista do Curimatau" (COAGRO) in the Cuite region, PB, in a layer 25 cm high, under average temperatures of drying air of 90 and 100°C and flow of the air of 0.9 m.s4. The third drying was carried out on a hard cement floor and in a thin layer. The water activity was also studied trough curves of sorption for the temperatures of 20, 30 and 40°C, by means of the static gravimetric model on the range on the relative humidity from 16,3 to 87,7% and, furthermore, parameters between natural and artificial drying were established, besides the characterisation of algarroba trough the study of its chemical components. The data analyses permitted the conclusion that the kinetic of drying is strongly influenced by temperature, with reduction of the time of drying necessary to reach 7% of humidity from 220 minutes at 80°C to 85 minutes when one operates at 100°C. The periodic revolving of pods of algarroba during the drying in a thick layer made it more homogeneous and efficient. The kinetic of drying of pods of algarroba occurs in the period of decreasing rate and is not largely influenced by the air speed of drying (0.6 and 1.5 m.s"1), allowing the work of low outflows. The natural drying was found inadequate to low the humidity of pods of algarroba until the point of triturating. The models used (BET, Oswin and Halsey), were satisfactory by adjusted to the data to predict the hygroscopic balance of pods of algarroba. The chemical components evaluated were not largely influenced by the air speed of drying, however, with the increase of temperature occurs a tendency to decrease the percentage of organic matter and increase of protein, dry matter, gross fat and ash.