Protein Quality of Amaranth Grains Cultivated in Ethiopia as Affected by Popping and Fermentation

Abstract

The effect of popping and fermentation on protein quality of three different varieties of amaranth grains cultivated in Ethiopia was evaluated. Total lysine content of the grains was higher than that of commonly available cereals but close to that of legumes. Methionine and cysteine contents in the grains were also higher than that found in cereal and legume proteins. Percentage of total indispensable amino acids, excluding tryptophan, was 43%-49%, which was higher than WHO reference pattern (31%). Popping resulted in 36% and 37% reduction in total lysine and cysteine contents, respectively, whereas fermentation reduced cysteine, lysine and methionine contents by 16%, 20% and 20%, respectively. From the free amino acids, histidine was the major indispensable amino acid but threonine was not detected. During popping, all free amino acids, except threonine, were reduced. On the other hand, fermentation significantly increased (p < 0.01) most amino acids except arginine, which was significantly decreased (p < 0.01), and tyrosine and glutamic acid, for which no change was observed. Popping decreased in vitro protein digestibility (IVPD) by 8.3%-17.1% while fermentation increased IVPD by 4.8%-7.5%. Substitution of amaranth for wheat and/or maize during complementary food formulation could contribute much to the daily requirements of indispensable amino acids of young children.

Effects of ball‐milling treatment on mussel (Mytilus edulis) protein: structure, functional properties and in vitro digestibility

“…In vitro protein digestibility was performed according to a previous report with some modification (Amare et al, 2015). Briefly, 15 mL of 0.1 M HCl containing 2.5 mg pepsin (Sigma, P-7125, 400 U mg À1 ) was added into 0.25 g of ball-milled mussel protein and then incubated at 37°C with gentle shaking for 2 h. After digesting, the solution was adjusted to pH 8.0 using 0.1 M NaOH, and then, 5 mg of pancreatin (Sigma, P-3292, 4*USP specifications) was added and incubated at 37°C for 4 h. After incubation, trichloroacetic acid was added to a final concentration of 10%.…”

Effect of popping and fermentation on proximate composition, minerals and absorption inhibitors, and mineral bioavailability of Amaranthus caudatus grain cultivated in Ethiopia

“…Cleaned and sun dried amaranth grains were popped as described in Amare et al (2015). Briefly, the sun dried seeds were placed in a hot clay pan for 10-15 s until popping.…”

“…The high level of protein also presents a unique functional attributes such as high foaming and water absorption property of amaranth flour (Shevkani et al 2014). Moreover, it has excellent amino acid profile with high amount of lysine and sulfur containing amino acids which are lacking in cereals and legumes, respectively (Amare et al 2015). Amaranth oil is rich in unsaturated fatty acids and also contains a significant amount of squalene which can potentially prevent skin cancer and decrease serum cholesterol level (He et al 2002).…”

Effect of Various Process Conditions on the Nutritional and Bioactive Compounds of Amaranth

“…In relation to the effect of processing on amino acids, Table 3 shows that the content of several amino acids is decreased as a consequence of the popping. The loss of tyrosine was the highest, followed by phenylalanine, cysteine, and lysine; in a different study, Amere et al [23] reported that aromatic amino acids were strongly affected, phenylalanine and tyrosine completely vanished, 90% of tryptophan vanished during popping, and nonenzymatic browning reaction is the most probable explanation for the decrease in the level of amino acids during heat treatment [24].…”

“…The effect of fermentation on free amino acid content from different pigmented Amaranthus grains was studied by Amere et al [23]; the results of the study showed that almost all amino acids increased. Tyrosine, glutamic acid and proline remained unchanged while arginine strongly decreased.…”