Characterisation of partially hydrolysed galactomannan from Caesalpinia pulcherrima seeds as a potential dietary fibre

Abstract

A galactomannan extracted from the endosperm of Caesalpinia pulcherrima seeds was submitted to partial enzymatic hydrolysis to overcome the limitation of use of this polysaccharide as a dietary fibre ingredient, since the intact galactomannan may promote a considerable increase in the viscosity of food products, even when added at low concentrations. The total dietary fibre recovered from the partially hydrolysed galactomannan (PHGM) was 78.27%. The molar mass of PHGM and the absolute viscosity of aqueous solutions were reduced in relation to the intact galactomannan. Nevertheless, their structural characteristics were very similar when evaluated by thermogravimetric analysis, infrared spectroscopy, and also by 1H and 13C nuclear magnetic resonance. A lack of growth promotion in the food-grade strains tested using PHGM during a preliminary in vitro fermentation assay suggests that the metabolism of these microorganisms most likely would not affect the galactomannan content in products during their production and storage. PHGM presented suitable properties to be added as an alternative dietary fibre source in a wide range of food products, particularly in beverages.