ETUDE DE L’EXTRACTION ET ÉVALUATION DES SUBSTANCES PECTIQUES VALORISABLES À PARTIR DES RÉSIDUS VÉGÉTAUX ET LEURS APPLICATIONS

Abstract

This work is part of an approach to valorizing local plant resources through the study of the prickly pear cactus (Opuntia ficus indica), a xerophytic plant widely distributed in arid and semi arid areas of Algeria. Recognized for its richness in bioactive compounds (pectins, flavonoids, mucilages, phenolic acids, vitamins and minerals), which represents a promising source for the development of high value added products in the agri food, cosmetic and pharmaceutical sectors. The main objective of this work was to optimize the conditions for extracting pectin from prickly pear cacti, considering different extraction methods (acid chemical, complexing agents, etc.). It was confirmed that the extraction method significantly influ ences the quantity and quality of extracted pectin. Extraction with acid hydrolysis gave a yield of 1.2%, compared to extraction by ultrasound and complexing agent, which showed different yields depending on the experimental conditions. The acid hydrolysis extraction, which showed the best yield, was optimized by an experimental design to establish a mathematical model. The optimal extraction conditions are: a temperature of 90°C, an acid concentration of 0.10 and an extraction time of 45 minutes, with an optimal yield of 1.2%. The extracts obtained from the prickly pear cactus pads were thoroughly characterized. The initial moisture content of the pads revealed a significant water content, reflecting the succulent nature of the plant tiss ue. The extracted pectin was analyzed for its moisture content, equivalent weight, as well as its methoxyl content (MeO 4.71%), allowing its gelling capacity to be evaluated. The content of galacturonic acid, the main constituent of pectin, was determined (46.11%), as was the degree of esterification (DE 84.6%), a key indicator of its technological functionality. In addition, an infrared spectroscopy (IR) analysis made it possible to identify the characteristic functional groups, confirming the polysacchari de nature of the product obtained and the presence of ester and hydroxyl groups These data confirm the potential of the prickly pear as a strategic raw material for sustainable industrial applications, while contributing to the economic development of disadvantaged regions and the fight against desertification.