Galactomannans (GMs) are polysaccharides with diverse industrial applications due to their functional properties, such as their use in thickeners, stabilizers, and gelling agents. Their use originated in the food industry and has rapidly expanded to other industries due to their biocompatibility, biodegradability, non-toxicity, and low cost. Galactomannans can be extracted from different plant species, resulting in gums with diverse physicochemical properties. Furthermore, there are different methods for their extraction and purification, each with their own advantages and disadvantages. The structure of galactomannans determines their application in industry, so their characterization is also important. This article presents a comprehensive review of galactomannan sources, as well as their extraction, purification, and characterization methods. It also includes the main applications of these polysaccharides in various sectors.

Oxides with the perovskite type structure of formula LnCoO₃, where Ln is a rare earth element, have unique physical and chemical properties. These materials are applied in catalysis, gas sensors, and electrodes for solid oxide fuel cells, among others. In this work, single-phase DyCoO₃ was obtained at 900°C using the solution-polymerization method. The microstructure of this material corresponds to a dendritic-type shape, with grain size between 0.2 and 8 μm and abundant porosity. The ultraviolet (UV) sensing characterization was performed on sintered pellets made with the as-prepared DyCoO₃ powder. The UV source was a light emitting diode (LED) of wavelength (λ) of 365 nm. The detection of this radiation, with constant optical irradiance (Ee), produced uniform and reproducible response patterns. When Ee was increased, the graphs revealed a quantitative detection of the light. Analogous results were obtained using light of larger wavelengths: λ = 400, 449, and 642 nm. The graphs display a decrease on the variation of the photocurrent by increasing λ, corresponding to a decrease on the energy of the incoming photons. On the other hand, the photocatalytic decomposition of malachite green under UV radiation was investigated using powder of DyCoO₃. The results show a decrease of the absorbance by increasing the UV exposure time, indicating the degradation of the dye. Since DyCoO₃ is a p-type semiconductor material, the generation of electrical charge carriers under UV radiation explains its photocurrent and photocatalytic properties. In general, these properties can be applied in UV sensors to prevent skin cancer, photoconductive materials for solar photocells, and photocatalysis to decompose organic dyes.