Concentration and desalination of zampa (Atriplex lampa) extract by membrane technology

The high amino acid content (lysine, meteonin and tryptofan) of most leaf proteins makes them suitable as supplements for cereal flours, which are deficient in these amino acids. These proteins are used in cattle balanced foods. In this work, separative membrane technology, ultrafiltration (UF) and discontinuous diafiltration (DD), was used to obtain a protein concentrate from an aqueous extract of Atriplex lampa, a chenopodiaceous shrub abundant in the arid and semi-arid regions of the Province of San Luis, Argentina, for the purpose of improving its palatability, affected by its high salt content. The parameters and operation conditions were studied in the pretreatment of feed as well as in UF process to obtain maximum performance. This procedure was found to be a convenient method for concentrating soluble protein contained in aqueous extract of “zampa”, using inorganic membranes of 15 kD molecular weight (MWCO). The final concentrate was dried on a vacuum stove at 35°C. The concentrate had a protein content of 71% (dry weight basis) and a marked decrease of salt content, from 38% in the leaf to 2.1% after processing. No adsorption or critical fouling phenomena were observed during the process, which allowed performing a conventional wash cycle to restore the initial conditions of the membrane.

The technique used in this work allowed obtaining a good quality leaf protein concentrate from Atriplex aqueous extract. The inorganic membrane (15 kD molecular cut-off) was suitable for performing protein concentration and desalination in the UF–DD process. After the flux was stabilized, no important flux decreases took place, which suggests a low effect of membrane fouling in the course of the process. A protein concentration of 71% (dry weight bases) and a marked decrease of salt content (from 38% to 2.1%) were obtained. Finally, UF–DD allowed the improvement of the product palatability and enhanced other functional properties of leaf proteins, thus obtaining a product which is apt to be used as a supplement in animal diets.