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Abstract

The purpose of this study was to evaluate the effect of pH on the extraction of protein nitrogen from Atriplex lampa leaves (Moquin) Dietrich. The chemical characterization of the dry matter indicated the following (g/100 g): protein, 26.93; ash, 21.80; ether extract, 4.65; dry matter, 37.30; sodium, 6.05; and calcium, 0.41. Non-critical values were obtained for saponins and nitrates. The high concentration of oxalic acid (8.52 g/100 g), together with elevated salt content account for the low palatability of the studied species. In order to determine the parameters needed to improve the extraction in protein nitrogen from leaves, fresh material was macerated with 2% sodium metasulfite, followed by pulping with a hand-driven grinder. Extractions were performed at different pH values (2-12) adjusting the value with 5N HCL or NaOH, with agitation followed by centrifugation and pressing. Supernatants were collected and kept. The last extraction was performed with Tween 20 in order to obtain maximum nitrogen recovery from the residue cake. Highest extraction (41.23%) was obtained at pH 10 with a 1:5 ratio (leaf: deionized water, w/v). It is proposed that this regional natural resource may be used to elaborate a protein concentrate, which can be made more palatable by decreasing potassium and sodium salt content with the use of membrane technology.

Extraction of Proteins from Switchgrass Using Aqueous Ammonia within an Integrated Biorefinery

“…The amount of protein extracted increased dramatically from a pH of 8 to 10.5 before leveling off. Similar trends have been seen in other types of biomass [10][11][12][13][14][15][16]. Most proteins have an acidic isoelectric point, the pH at which the protein will have no net charge and therefore be the least soluble in a polar medium.…”

“…Protein yields varied considerably depending upon the types of biomass, generally resulting in high yields of protein from grains and moderate to low yields from leaf proteins. Studies with Atriplex leaves obtained only 41% of the total protein, while a pilot plant extracting proteins from alfalfa obtained 47% of the total protein [15,16]. In general, it appears that simple extractions are not sufficient to obtain complete protein recovery from leafy biomass.…”

“…There have been no reported studies of extracting proteins from switchgrass, although several other types of biomass have been considered for production of protein concentrates [10][11][12][13][14][15][16]. Dilute solutions of a strong alkali such as sodium hydroxide are generally used, with the pH between 8 and 12.…”

Development of algae biorefinery concepts for biofuels and bioproducts; a perspective on process-compatible products and their impact on cost-reduction

“…21,70,81,123,[215][216][217][218][219][220][221] Related work on producing leaf protein from terrestrial biomass biorefineries for human nutrition may also be applicable to algae biorefineries. 7,222,223 The quality (and thus value) of algal protein for human or animal consumption depends on the amino acid composition, in particular the respective concentration of limiting amino acids, palatability and digestibility of the proteins, and the amount of non-protein nitrogen and other potential anti-nutritional components.…”

“…In general, protein from algae shows good nutritional characteristics, 216,224,225 and a typical amino acid composition of the three major genera discussed in this review is shown in Table 8. 7,222,223 Integrating food or feed uses of fractionated or extracted algae will need to be tested to ensure that these industrially processed residues remain a good nutritional…”