Table 2.

Mucilage and pectin extraction procedures, yields, and compositions from cladodes of Opuntia spp.

Species/Variety	Extraction Procedure	Yield of Extraction (%)	Main Compounds Found	Conclusions	Ref.
Opuntia ficus-indica	Cladode powder was subjected to a sequential extraction to obtain water-soluble pectins (WSP), chelating-soluble pectins (CSP), and acid-soluble pectins (ASP).	WSP: 5.75% (w/w) of dry weight CSP: 0.21% (w/w) of dry weight ASP: 0.11% (w/w) of dry weight	Monosaccharide composition: Galactose Glucose Galacturonic acid Arabinose Xylose Rhamnose Mannose	All the pectin fractions obtained are mostly rich in galacturonic acid. Through the degree of methylation analysis, it was shown that all pectin fractions are lowly methylated (DM < 50%).	[60]
Opuntia ficus-indica	Mucilage extraction: Cladodes were washed and cut, and the interior was removed and pressed. Mucilage was precipitated in ethanol in a ratio of 2:3 (extract: ethanol). The precipitate was collected, washed with ethanol, dried (50 °C, 24 h), and then pulverized.	Not presented	Monosaccharide composition: Galactose Arabinose Xylose Rhamnose Glucose	The major sugars present in cactus mucilage are galactose and arabinose.	[61]
Opuntia monocantha	Mucilage extraction: Cladodes were washed, cut, and crushed. The resulting pulp was mixed with water at a ratio of 1:2 w/v (pulp: water), stirred, and heated (80 °C, 30 min). The mixture was filtered and centrifuged. The supernatant was precipitated in 95% ethanol and kept overnight at 4 °C. The mucilage was filtered under vacuum, dried, and sieved.	12.0% (w/w) of dry weight	Monosaccharide composition: Arabinose Galactose Glucose Rhamnose Xylose Galacturonic acid Glucuronic acid	The extraction method shows promising results for obtaining mucilage powder, which is mainly composed of carbohydrates.	[54]
Opuntia ficus-indica	Total pectic mucilage fraction extraction (TFC): Extraction is performed in a water bath using water as the solvent (adjusting the pH). The mixture was filtered and centrifuged, and the supernatant was concentrated. The solution was precipitated in isopropanol (4 °C, overnight). The resulting precipitate was centrifuged, washed with ethanol, and dried. Mucilage fraction extraction (MC): The extraction procedure was performed under agitation with water as the solvent and centrifuged. The supernatant was precipitated with isopropanol (4 °C, overnight), then washed with absolute ethanol and dried. Pectin fraction extraction (PC): obtained by the same method used for total pectic mucilage fraction; using the residues from the mucilage extraction as starting materials.	TFC: 13.1% (w/w) of dry weight MC: 10.2% (w/w) of dry weight PC: 6.13% (w/w) of dry weight	High content in carbohydrates	Extraction conditions may affect the extraction yield. PC was richer in uronic acid content than the other two fractions. Mucilage showed a lower content of uronic acid.	[57]
Opuntia ficus-indica	Pectin extraction: extraction from cladode’s powder was made with water, centrifuged, and the resulting residues were dried. The residues were mixed with water in an ultrasound water bath and centrifuged. The supernatant was precipitated in isopropanol and then dried.	18.6% (w/w) of dry weight	High uronic acid content	The use of ultrasounds increased the pectin extraction and reduced the extraction time when compared with chemical extraction methods.	[62]
Opuntia ficus-indica	Mucilage was extracted from cladodes by performing a microwave-assisted extraction (different powers were applied). Then the samples were filtered, centrifuged, and precipitated in ethanol. The resulting precipitate was washed with ethanol and lyophilized.	8.13% (w/w) of dry weight with 500 W for 7 min	Monosaccharide composition: Galactose Arabinose Xylose Rhamnose Glucose	Microwave irradiation promotes the interaction between the solvent and the material, enhancing the extraction.	[63]
Opuntia dillenii (Ker-Gawl) Haw	Mucilage extraction: fresh cladodes were extracted with water under stirring. The solution was filtered and concentrated. The concentrated solution was precipitated with and dialyzed against water (24 h, membrane of 12–14 kDa) and lyophilized.	6.20% (w/w) of dry weight	Monosaccharide composition: Arabinose Galactose Rhamnose Xylose Glucose Uronic acid	The major neutral sugars found were arabinose and galactose. The uronic acid was found in a lower percentage (2.5%), demonstrating the neutrality of the mucilage.	[64]
Opuntia ficus-indica	Mucilage was previously extracted from cladodes, and the resulting residue was used for pectin enzyme-assisted extraction. Xylanase and cellulase were added under optimal conditions. After enzyme inactivation, the mixture was centrifuged, and the supernatant was precipitated with isopropanol. The precipitate was centrifuged, dried at 50 °C, and reduced to powder.	16.7% (w/w) of dry weight	Arabinose Xylose Fructose Glutamic acid Galacturonic acid Glucose Galactose Mannose Rhamnose	Enzyme-assisted extraction proved effective for enhancing pectin extraction without using acid treatments. The resulting pectin was lowly methylated and showed a galacturonic acid content of 65%.	[65]
Opuntia ficus-indica	Pectin extraction was performed under three different extraction conditions: acidic (pH = 2), neutral (pH = 6), and basic (pH = 10). The samples were submitted to ultrasound and then placed under mechanical stirring, filtered, and centrifuged. The residues were submitted to the same extraction, and the supernatant was mixed at the end. The resulting supernatants were precipitated in ethanol and filtered. The residues were dialyzed (30 kDa membrane) against water, concentrated, and lyophilized.	Acidic (pH = 2): 8.80% (w/w) of dry weight Neutral (pH = 6): 24.5% (w/w) of dry weight Basic (pH = 10): 4.60% (w/w) of dry weight	Neutral sugars Galacturonic acid	Neutral extraction obtained the highest total yield, although acidic extraction presented a higher galacturonic acid content.	[66]
Opuntia ficus-indica	Mucilage extraction was performed by extrusion. The solution was centrifuged, and the supernatant was precipitated in ethanol and dried.	1.50% (w/w) of dry weight	Not assessed	The yield of extraction was demonstrated to be dependent on mucilage synthesis, which depends on edaphoclimatic conditions.	[67]
Opuntia spinulifera Salm-Dyck	Mucilage extraction was accomplished by mixing cladodes with water under stirring and filtering at the end (process repeated four times). The filtrate obtained was precipitated with ethanol, dried, and reduced to powder.	Not assessed	Arabinose Rhamnose Xylose Galactose Uronic acid	Cladodes from Opuntia spinulifera are rich in carbohydrates. Furthermore, the presence of pectins was found through Fourier-Transform Infrared Spectroscopy (FTIR) analysis. This could be explained by the ability of pectins to also precipitate in ethanol.	[68]
Opuntia ficus-indica	Residue from cladode’s flour was obtained by depigmentation with ethanol and acetone and centrifugation. The extraction was performed by mixing EDTA and water, adjusting the pH, and stirring. Then, a centrifugation was performed, and the supernatant was precipitated. The precipitate was recovered through centrifugation and resuspended in water. The precipitate was filtered, and the solution was mixed with ethanol (5 °C, overnight), filtered again, and then dried.	10.4% (w/w) of dry weight under conditions of: pH = 11; 20% EDTA; 80 °C	Galacturonic acid Arabinose Galactose Glucose Rhamnose	Pectin extractions under alkaline conditions demonstrated a higher yield than those performed under acidic conditions. The use of EDTA suggests that the chelation of calcium is an important factor in extraction.	[69]