The ultrafiltration (UF) of cactus juices has been carried out for the purpose of clarification from an enzymatically pre‐treated fruit. Concentration of mucilage (Opuntia ficus‐indica) by cross‐flow ultrafiltration, obtained by solvent‐free mechanical extraction, using 1, 10, and 30 kDa membranes has been carried out. The η_E was 39.49% and the energy consumption was 247 times less than the evaporation one. The 1 kDa concentrated mucilage had the highest η_UF and total soluble solids although the fastest process was with the 30 kDa membrane which also extends its shelf life up to 60 days at 4°C, preserving its viscous and viscoelastic properties and high contents of galacturonic acid, features desired to be applied as a dispersing agent. Chromatographic analysis shown that the passage of the monosaccharides during the ultrafiltration was in function of their position in the structure of mucilage molecule. Sugars such as galacturonic acid and galactose were conserved after filtration; however, decreased the concentration of sugars that make up the side chains (rhamnose, glucose, arabinose, and xylose) of the mucilage molecule.

Mucilage (Opuntia ficus‐indica) is a complex carbohydrate that is attractive to the food industry due to its excellent functional properties. Various authors have used vacuum evaporation or and membranes to clarify and concentrate mucilage but an enzymatic pre‐treatment is carried out due to the gelling properties of the polysaccharide. In this work cactus extract obtained by the solvent‐free mechanical process was concentrated with UF membranes without enzymatic treatment. UF process allowed to concentrate mucilage with good yield efficiency, low energy consumption and increases the shelf life of liquid form up to 60 days, preserving almost free of microorganisms as well as its viscous and viscoelastic properties and high contents of galacturonic acid, features which allows its application as stabilizer and thickener of nutritional supplements and preparation of functional drinks of nutritional value. The results obtained in this work might be extended to other cactus extracts that had wider industrial applicability.