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Opuntia ficus-indica (Cactaceae) is an attractive renewable resource from arid and semi-arid regions of the world, including the north of Africa and Tunisia. It has suitable potential for use as a cellulose source for producing carboxymethyl cellulose (CMC). The chemical composition of fibers obtained from underground (roots) and aerial (trunk) parts of Opuntia ficus-indica, such as cellulose, holocellulose, lignin and ashes, was determined using normed and standardized methods. Individualized cellulose fibers were extracted from both raw materials using an eco-friendly delignification process based on soft treatment with sodium hydroxide/hydrogen peroxide mixtures followed by mechanical operation. The extracted cellulose fibers were carboxymethylated using sodium hydroxide and mono-chloroacetic acid, in the aqueous ethanolic medium. In this work, novel eco-friendly hydrogel films were synthesized based on high-quality carboxymethyl cellulose "CMC-R" from the roots ([DS] = 0.64) and "CMC-T" from the trunk ([DS] = 0.97) cross-linked with citric acid. The produced hydrogel films from both CMCs have various morphological structures, acceptable mechanical properties, and improved barrier behaviors. However, CMC hydrogel films from Opuntia ficus-indica are totally biodegradable within 20 days and became good candidates to replace synthetic polymers in packaging films. [ABSTRACT FROM AUTHOR] more...

Opuntia ficus-indica mucilage is a renewable source of hydrocolloid carbohydrates with a high added value suitable for food and other industrial applications. The purpose of this research is to investigate the efficiency of mucilage extraction as an interesting emulsifying agent using the conventional one-step method versus the combined conventional and ultrasound-assisted extractions. The yield extraction of mucilage through conventional and combined methods from cooked cladodes was 19 ± 0.5 % and 22.8± 2.4 %, respectively. It was shown by the ATR-FTIR, XRD, and TGA spectra that mucilages have a carbohydrate structure, an amourphous appearance, and good thermal stability in some temperature ranges. All mucilage hydrocolloid solutions show non-Newtonian shear-thinning behavior in terms of viscosity. The zeta potential of emulsions stabilized with mucilage fractions ranged from 22.1±1.2 to 34.6± 1.7 mV. Ultrasound-assisted extraction combined with the conventional method is a green technology to extract mucilage from Opuntia ficus-indica cladodes with properties that can be used as a natural emulsifying agent for stable emulsions. • Ultrasound extraction method considered as a green technology to extract mucilage. • Opuntia ficus-indica mucilages are thermally stable. • The flow of mucilage solutions revealed the pseudo-plastic share-thinning behavior. • The challenges of using Opuntia ficus-indica mucilages as an emulsifier are proven. [ABSTRACT FROM AUTHOR] more...

Highlights • A green process was used to manually extract fibrous networks from the cactus plant. • Fibrous layers have a natural net-like structure with a low bulk density. • Fibrous networks have good thermal stability and suitable mechanical properties. Abstract The present study focuses on the extraction and characterization of natural cellulosic tissues from the cactus Opuntia ficus-indica. A major goal is the establishment of a "green" process for fibrous networks extraction that allows for biomass valorization using sustainable plant fibers. This process shall contribute to the eco-friendly concept. Numerous separated fibrous layers (tissues) with intricate structures were obtained from different parts of the plant. Bulk density and thicknesses of the fibrous layers were determined including evaluation of fiber swelling (water uptake test) and detailed arrangement of the fibrous layers according to thickness was given. A good layer distribution and different values of bulk density were obtained for the studied tissues. The macrostructure (topology and geometric parameters) and microstructure (internal and anatomical structures) of fibrous networks were studied using both bright-field microscopy and scanning electron microscopy. A high diversity of fibers having a complex hierarchical structure was observed. The study of the fibrous-networks crystallinity and the thermostability indicate that water-immersion processing ameliorated the thermal stability in some temperature regions. The fibrous networks mechanical studies were examined, and the results showed a good response strength, especially for uniaxial tensile layers, which has led to the highest strength and elastic modulus. [ABSTRACT FROM AUTHOR] more...

This study evaluated the feasibility of using cactus mucilage (CM) to elaborate biobased composite films blended with styrene-butadiene rubber latex (SBL). The CM was extracted and precipitated with ethanol (CMET) and isopropanol (CMIS). Mucilage-based films were formulated using three levels of mucilage (4, 6, and 8 wt%). The microstructure, thickness, moisture content, density, water contact angle, water vapor permeability, film solubility, thermal stability, and toughness of mucilage films blended with SBL (SBL/CMET and SBL/CMIS) were measured. The properties of mucilage-based films varied systematically, depending on the concentration of mucilage. The addition of SBL to CM film produces compatible, hydrophobic, flexible, and stiffer films with low moisture contents and good barrier properties. The mucilage film incorporated with 6 wt% CMET and CMIS reached the highest Young's modulus of 1512 ± 21 and 1988 ± 55 MPa, respectively. The DSC of produced films reveals that the Tg of SBL/CMIS is lower than that of SBL/CMIS. The synthesized films were structurally stable at high temperatures. The biodegradability of the composite films buried in the ground shows that the produced films are 100 % biodegradable after 40 days. Thus, CM blended with SBL can benefit specific applications, especially food packaging. [ABSTRACT FROM AUTHOR] more...

This paper discusses mucilage extracted from Opuntia ficus-indica (Cactaceae) cladodes, also known as Barbary fig. Mucilaginous polysaccharides were extracted in hot water and purified with two distinct organic solvents, ethanol and isopropanol. The mucilaginous extract yield precipitated in isopropanol "MUIS″ (i.e. 23.2%) is higher than that of ethanol "MUET″ (i.e. 19%). The biochemical composition of mucilaginous extracts shows that the change in precipitation solvents has no significant effect. In addition, the microstructure of mucilaginous extracts exhibits amorphous and porous structures, which favor their capacity to retain moisture. The mucilaginous extracts analysis by ion chromatography reveals that after acid hydrolysis, MUIS has a higher total of sugars (46.9%) than MUET (37.6%). Mucilaginous extracts vary in their main content of monomers such as arabinose, galactose, glucose, and xylose as well as in the uronic acid fraction. The contact angle measurements were also established in order to investigate mucilaginous extracts' hydrophilic or hydrophobic surfaces. Three tested liquids were used namely: distilled water, diiodomethane, and ethylene glycol. The X-ray diffraction analysis displayed that the precipitation solvent does not affect the amorphous structure. The TGA analyses of extracts under an oxidative atmosphere reveal that the oxygen flow accelerates the kinetics of degradation. Under nitrogen flow, mucilaginous extracts have intrinsic thermal resistance in specific temperature ranges. The DSC results show that the polysaccharide purification technique influences the glass temperature (Tg), which is around 53 °C and 61 °C for MUET and MUIS, respectively. In an aqueous solution, the mucilaginous extracts are highly heterogeneous, and the precipitation solvents and temperature affect their particle size. Mucilaginous extracts were concentration-dependent and reduced the surface tension of water to 43.5 mN/m and 30 mN/m for MUET and MUIS at 7 w/v%, respectively. The rheological analyses show that a non-Newtonian shear-thinning behavior was observed. The Ostwald-de Waele model successfully predicted the viscosity-shear rate relationship. The consistency coefficient (k) of MUIS at 7 w/v% (0.117 Pa.s) is higher than MUET at 7 w/v% (0.081 Pa.s). The critical concentrations (C*) of MUET and MUIS are 1.75% and 3.45 w/v%, respectively. • Opuntia ficus-indica mucilage was extracted and precipitated with two organic solvents. • Precipitating solvent affects composition and properties of mucilage extracts. • Mucilage extracts are thermally resistant under a nitrogen atmosphere. • Mucilage extracts exhibit distinct surface tension and rheological characteristics. [ABSTRACT FROM AUTHOR] more...