Physicochemical and functional characterization of the mucilage obtained from cladodes of two Opuntia species

The mucilage is an interesting compound found in cladodes of species of Opuntia (Cactaceae). The aim of this work was to extract the mucilages from Opuntia ficus-indica (OFI) and O. quimilo (OQ) cladodes and to examine their physicochemical characteristics, microstructure, and functional properties in solution. The mucilages exhibited high contents of carbohydrates, proteins, and minerals. Both mucilages presented a diverse monosaccharide composition, mainly constituted of galactose and arabinose. The FTIR spectra showed characteristic polysaccharide nature, whereas the diffractograms demonstrated an amorphous structure. The intrinsic viscosity of OFI mucilage was 3.08 dL/g, while that of OQ mucilage was 10.33 dL/g. Although the molecular weights of both mucilages are in the order of those of commercial gums, that of OQ was higher. This is consistent with the pseudoplastic behavior of OQ mucilage. However, OFI mucilage showed Newtonian behavior over the range of concentrations evaluated. This is fully consistent with that of semi-diluted solutions and in accordance with the lower molecular weight of this mucilage. The mucilages presented maximum solubility at 60 °C, although the mucilage of OFI was slightly more soluble than that of OQ. The chemical composition and functional properties of the mucilages can be affected by the extraction method and conditions.