Extraction processes and characterization of the mucilage obtained from green fruits of Pereskia aculeata Miller

Abstract

Pereskia aculeata Miller is a cactus known for its non-toxic mucilage. This mucilage is usually extracted from its leaves and fruits, and is rich in the polysaccharide arabinogalactan and proteins, enabling its application as an emulsifier and a stabilizer in the food industry. In this work, the mucilage powder was obtained from green fruits of Pereskia aculeata Miller and characterized to determine its physicochemical, thermal, and microstructural properties. In addition, the technological characteristics of the reconstituted powder were evaluated. The freezing point of the solutions tested, regardless of the concentration of mucilage used, was on average −2 °C. Through the micrograph of the powder, it was possible to visualize an amorphous structure with high porosity and heterogeneity in relation to the average grain diameter. Infrared spectroscopy revealed the presence of bands and peaks characteristic of polysaccharides and protein chains. By thermogravimetric analysis, the thermal degradation of these biopolymers was observed in the range of 290 °C to 350 °C. The glass transition temperature and melting point (endothermic event) of the material were observed at −5 °C and at 68 °C, respectively. All the mucilage solutions studied showed pseudoplastic behavior. Increasing the mucilage concentration of the medium contributed to the increase in the apparent viscosity, emulsification capacity, emulsion stability, and decrease in the mean size of the oil droplets. When compared to the mucilage powder extracted from the leaves, the mucilage powder extracted from the fruit showed approximately twice the protein content with low water activity and a clarified product with light yellow coloration.