EVALUATION OF THE PRIMARY DEPITHING OF BANANA STEM AS PRE-PROCESSING FOR PULPING

摘要

During the cycle of commercial production of bananas it is observed formation of agricultural residues, that almost always has as final destination the incorporation into the soil as spare source of nutrients. However, stem, part of the plant responsible for fruit sustentation, is removed from the field with the fruits, discarded and accumulated at the packinghouse or in the delivering centers and destined to the urban trash, being therefore considered a residue. The final destination of this residue is problematic and onerous, implying in expenses with carrier and manpower. Ahead of these facts, studies have been carried out to make possible the exploitation of banana plant stem, Musa sp, as raw material for pulp production. The chemical, morphologic and anatomical features of stem make difficult its use as raw material source for pulp production. The stem in natura presents about 93 % of humidity, prolonged format and many parenchyma cells. Aiming its exploitation in the pulp production, in this work the possibility of reduction of stem for smaller particles was evaluated, without affecting the fiber properties. In a sample of 100 in natura stem, it was determined the weight, size, and diameter; later this material was processed in cutter defibrator especially regulated to reduce it into smaller particles that were called bagasse. The bagasse was characterized through the apparent density, humidity, chemical and morphologic composition. The results showed that bagasse can be considered as an appropriate raw material for pulp production, due to the reduction of its desegregated form into particles of about 1.3 cm in size, made of fiber beams and parenchyma cells; the advantages of the bagasse are: simplicity manipulation and digesters feeding. The chemical composition and humidity of the bagasse related to its original form did not change after the mechanical processing: 7,4% of lignin, 45,6% of holocellulose, 47% of extractives and 92,4 % of humidity.