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.
The purpose of this study was to evaluate the use of ultrafiltration and discontinuous diafiltration (DD) to obtain a protein concentrate from Atriplex lampa saltbush, improving its palatability by decreasing the salt content (mainly sodium and potassium chloride). The experimental work was done using a Pellicon cassette (25 units) system equipped with polyethersulfone organic membranes with a molecular weight cut-off value of 10 kD. The characteristic of the membranes and the feed material, the parameters and operational conditions were studied in the pretreatment of the sample as well as in the ultrafiltration process to obtain a maximum performance. The product obtained contained 85% protein on aa dry weight basis and a marked decrease in salt content, from 40% in fresh leaves to 2.5% after processing by DD, which is in agreement with the average conductivity values observed, from 18.1 mS cm −1 in the initial aqueous alkaline extract to a final value of 3.5 mS cm −1 . Measurements of normalized water permeability were determined after each wash cycle in order to verify the flow recovery through the membrane. Analysis of amino acids from the protein concentrate with a chemical score of 85.13 was calculated using a Food Agricultural Organization reference pattern (sulfur amino acids as limiting amino acids). Nitrogen retention was evaluated by means of a biological test and the following values were obtained: net protein utilization = 63.00 ± 4.00, true digestibility = 79.00 ± 5.21, and biological value = 79.80. The presence of oxalic acid, nitrates, saponins, phenolic compounds and condensate tannins is not significant. The results indicate that the concentrate obtained has a high content of lysine, making these products particularly useful as a complement for cereal flour, which is deficient in this amino acid. The determined values suggest that the product can be used in balanced animal feed formulation.
The chemical and nutritional composition of the aerial parts of Amaranthus muricatus was assessed. This is a wild plant growing well in arid and poor soil, which are not suitable for cereals. The material under study was boiled, dried and ground and then evaluated for chemical, nutritional and antinutritional properties. Protein concentration of the amaranth flour was 15.74 g/100 g and total dietary fiber content was high (53.81 g/100 g), with 79% coming from insoluble dietary fiber. The calcium content was 1533 mg/100 g and the Ca/P ratio (5.94) was markedly higher than the value suggested in the 1989 Recommended Dietary Allowances. Fifty-nine percent of the fatty acids present were unsaturated with linoleic acid accounting for 40% of the total fatty acid content. Nitrate, hemagglutinin, trypsin inhibitor and saponin contents were within the non-critical values. Net protein utilization (NPU), true digestibility (tD) and biological value (BV) measurements indicated a nitrogen gain of 74% that of casein. The results of this study indicate a nutritive potential for the A. muricatus leaves, therefore, domestication of this plant is suggested along with assessment of its chemical and nutritional properties.
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