Prickly Pear Peels As a Valuable Resource of Added-value Polysaccharide: Study of Structural, Functional and Film Forming Properties

Valorization of agricultural by-products constitutes a promising approach for sustainable development. Mucilage was extracted with a simple and safe method from Opuntia ficus-indica fruit peels which are considered as unexploited wastes resulting from the huge consumption of prickly pears. Structural and functional properties of the extracted polysaccharide were studied. Peels mucilage was composed of 97% carbohydrates, essentially galactose, arabinose, xylose and galacturonic acid. Specific signals of these sugars were observed in C and H NMR spectra and their chemical fingerprint was obtained by ATR-FTIR. Viscosity measurements of mucilage solution revealed a shear-thinning behavior. The extracted biopolymer exhibited good solubility in water, foaming and emulsifying capacities. Favorable thermal stability was manifested up to 250 °C. In order to conceive novel applications of this biopolymer as biodegradable packaging, its film-forming properties were studied. Red-colored films were obtained with high water contact angle (~91°), solubility (~42%) and grease proof character. Mechanical properties were comparable to those of other polysaccharides films with decent elongation at break reaching 66%.