Extração da Galactomanana por diferentes métodos e caracterização das vagens de algaroba (Prosopis Juliflora)

Abstract

The Brazilian semiarid region corresponds to 10% of the country and despite low rainfall, hot and dry weather has high biodiversity. Among the plants belonging to the flora of the caatinga, it is possible to find the Prosopis juliflora, Leguminoseae family exhibiting as characteristic of this group of plants the existence of polysaccharides of reserves in the cell wall of seeds of Leguminoseae. One of the polysaccharide is the galactomannan, it is formed by D-glucose and D-mannose units, in this study was extracted from two forms, a conventional method which comprises the use of only water and ethanol, and another method, was the use of ultrasound high power plus the use of water and ethanol. The first step was made the pretreatment of string beans, in which they were placed in the sun, swollen, broken, decanted to separate the caps and fibers, then they were milled. After, 200 g of the capsule powder was added to 1200 ml of distilled water and the system was heated and homogenized with a mechanical stirrer. Then it was centrifuged and the viscous supernant solution was precipitated with ethanol in a 1: 2 solution in relation for alcohol. The mixture containing galactomannan was again centrifuged and placed to dry in an oven at 55 ° C. The yield average for this extraction was 5.95%. The extraction was performed with ultrasound only changing the mechanical stirrer and heater plate by ultrasound. The procedures were performed with powers of 100, 75 and 50% with times of 30 and 60 minutes. The average yield for the tests was 4.5%, lower than the yield of conventional method. After that the galactomannans obtained by the two methods were characterized for comparison therebetween. Analyses were performed FTIR, DSC and TGA, it was also done the determination of color, gray and moisture content. It was observed similar behavior in all analyzes for the extracted galactomannans. The lignocellulosic material fibers and capsules of algaroba were also analyzed according to TAPPI standards. FTIR and TGA analyzes were performed to study the composition and thermal behavior. The capsules and fibers showed similar results to those reported in the literature.