Caracterização e despolimerização ultrassônica de galactomanana de sementes de fava d’anta (Dimorphandra gardneriana) do Piauí

Abstract

Galactomannans are reserve polysaccharides found in legume seeds, composed of a main chain of D-mannopyranose (M) units linked by β (1→4) glycosidic bonds, substituted at α (1→6) by simple units of D-galactopyranose (G). The depolymerization of these polysaccharides results in derivatives with lower molar masses that can have expanded applications. The objective of this work is to characterize galactomannan extracted from Fava D’anta seeds (Dimorphandra gardneriana) collected in Piauí and to perform ultrasonic depolymerization of this galactomannan for future applications as a gastroprotective agent. The galactomannan was extracted from Fava D’anta pods with a yield of 26.5%, comparable to seeds collected in Ceará. The obtained gum showed a peak molar mass (Mpk) of 4.18x106 g/mol and a M/G ratio of 1.72:1. Characterizations demonstrated significant similarity between galactomannans, both in structural aspects and in rheological and thermogravimetric behavior, with minor differences likely due to variations in the collection locations and the age of the plants from which both samples were harvested. This study shows that it was possible to reduce the molar mass of the extracted galactomannan through ultrasonic degradation, and the influence of different parameters (temperature and power) on depolymerization efficiency. The studies revealed that the depolymerization process, accompanied by peak molar mass, follows a second-order kinetics. Tests conducted on the model, based on the depolymerization of a 1% (w/v) guar gum solution during 3 hours of sonication, demonstrated its effectiveness in describing depolymerization processes for a longer time range and higher concentration. Therefore, it proved to be a suitable model for the ultrasonic depolymerization kinetics of galactomannan from the studied sources.