Propriedades filmogênicas da mucilagem de Nopalea cochenillifera (L.) Salm-Dyck obtida com a reutilização de solvente orgânico

Abstract

The mucilage of pricky pear cactus (Nopalea cochenillifera Salm-Dyck) is composed of polysaccharides used in the preparation of polymers, which are interesting alternatives to petrochemical plastics, due to characteristics such as elasticity and the ability to form molecular networks. However, the extraction of mucilage, commonly performed with ethanol, as well as its disposal, intensifies the impacts due to its relative toxicity to the environment, in addition to the high cost. Thus, the objective was to implement methodologies that result in the reuse of alcohol for the process of mucilage extraction and elaboration of the biopolymer based on prickly pear cactus. N. cochenillifera cladodes were harvested and processed to obtain mucilage. The cladodes were cut, the aquifer parenchyma was removed and taken to a processor using ethanol. At the end of the processing, a whitish powder was obtained, which was hydrated both to perform the physicochemical analyzes on the mucilage and to formulate the biopolymers, which were characterized via thermal, optical, physicochemical and structural analyses. The residual ethanol from the extraction was distilled in a rotary evaporator to remove pigments and restore its alcohol content. After all the analyses, a new mucilage extraction was carried out, reusing the ethanol, and again, physical-chemical evaluations were carried out in the mucilage and in the solvent, in addition to, in the biopolymers obtained, thermal, optical, physical-chemical analysis and structural. It was observed in mucilage that pH, vitamin C content, total acidity, electrical conductivity and soluble solids did not vary significantly, regardless of the extractor used. The sodium and potassium contents, on the other hand, decreased when the mucilage was extracted with reused ethanol, indicating that it was efficient in removing these ions. In the ethanol from the first extraction, a high value of phenolic compounds and total soluble carbohydrates was quantified, while in the reused ethanol such values were considerably reduced, indicating that even it removed less mucilage components than the clean one, which enables the elaboration of more compact biopolymers as such components improve structural properties, such as moisture content and permeability to water vapor. The films from the second extraction were less soluble in water, thicker and more transparent, in addition to showing greater thermal stability than those from the first extraction. It is concluded that the reused ethanol improved the filmogenic properties of the mucilage, such as carbohydrates and phenolic compounds, in addition to not having removed nutritional components such as proteins, citric acid and ascorbic acid. The biopolymers from the extraction with reused alcohol, in addition to presenting better morphological aspects through their microstructure, also showed promising structural aspects, such as low water solubility and moisture content, indicating the reuse of the solvent as a good alternative to the use of pure ethanol, which makes the biopolymer manufacturing process more expensive, as well as promoting a greater amount of waste in the environment. However, studies are needed regarding the methodology of solvent reuse regarding the limit of its reuse potential, in order to make this procedure viable on industrial scales