The nutritive value of amaranth grain (Amaranthus caudatus)

A chromosome-level Amaranthus cruentus genome assembly highlights gene family evolution and biosynthetic gene clusters that may underpin the nutritional value of this traditional crop

Traditional crops have historically provided accessible and affordable nutrition to millions of rural dwellers but have been neglected, with most modern agricultural systems over-reliant on a small number of internationally traded crops. Traditional crops are typically well-adapted to local agro-ecological conditions and many are nutrient-dense. They can play a vital role in local food systems through enhanced nutrition (particularly where diets are dominated by starch crops), food security and livelihoods for smallholder farmers, and a climate-resilient and biodiverse agriculture. Using short-read, long-read and phased sequencing technologies, we generated a high-quality chromosome-level genome assembly for Amaranthus cruentus, an under-researched crop with micronutrient- and protein-rich leaves and gluten-free seed, but lacking improved varieties, with respect to productivity and quality traits. The 370.9 Mb genome demonstrates a shared whole genome duplication with a related species, Amaranthus hypochondriacus. Comparative genome analysis indicates chromosomal loss and fusion events following genome duplication that are common to both species, as well as fission of chromosome 2 in A. cruentus alone, giving rise to a haploid chromosome number of 17 (versus 16 in A. hypochondriacus). Genomic features potentially underlying the nutritional value of this crop include two A. cruentus-specific genes with a likely role in phytic acid synthesis (an anti-nutrient), expansion of ion transporter gene families, and identification of biosynthetic gene clusters conserved within the amaranth lineage. The A. cruentus genome assembly will underpin much-needed research and global breeding efforts to develop improved varieties for economically viable cultivation and realization of the benefits to global nutrition security and agrobiodiversity.

An evidence-based systematic review of amaranth (Amaranthus spp.) by the Natural Standard Research Collaboration

An evidence-based systematic review including written and statistical analysis of scientific literature, expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing.

Protein quality evaluation of amaranth in adult humans

This study was carried out to determine the nutritional quality of the protein of amaranth grain submitted to extrusion and popping processes, using cheese protein as reference. For the biological evaluation, the short-term nitrogen balance index method was followed with 12 experimental adult male human subjects. A Latin square series 3 x 3 was used (three periods, three subjects) as an experimental design balanced to minimize residual effects by randomly ordering treatments, columns and rows. The study consisted of three periods of nine days each. The first period started by feeding all subjects a low nitrogen diet, followed by increases of the protein level every two days. The levels were 0.2, 0.4, 0.6/g protein/kg/day, keeping other nutritional elements constant and adequate, including calories, minerals and vitamins. All subjects received all their meals using as a source of protein extruded amaranth, popped amaranth or processed cheese. Water intake was kept at a rate of 0.8-1.0 ml per calories consumed. During the study, the subjects maintained regular physical activity. Amaranthus cruentus was utilized. The extruded amaranth was prepared with the Brady Crop Cooker under conditions previously established in other studies. The popped amaranth was prepared at a 250 degrees C temperature during 15-20 sec. The extruded and popped amaranths were provided as a sweet puree and, as all the other foods conforming the diets of each subject, they were weighed with 0.1 g of accuracy. Diet samples, as well as faeces and urine, were collected daily, which were ordered according to period and level of protein, conforming pools to determine their nitrogen content by the Kjeldahl method. True digestibility results of the protein were 101.4, 89.8 and 85.5% for cheese, extruded amaranth and popped amaranth, respectively. The statistical analysis according to the Tukey test showed that the true digestibility of the protein was the same for the two products of amaranth and different than the digestibility of cheese. Nitrogen balance index values from the equation between nitrogen intake and nitrogen retained, were 0.97, 0.86 and 0.79 for cheese, extruded amaranth and popped amaranth, respectively. The respective values between nitrogen absorbed and nitrogen retained were 0.97, 0.98 and 0.96. The Tukey test indicated that for NI to NR cheese was statistically different for the two amaranth products, which were similar between them. For the relationship NA to NR all values were statistically the same.(ABSTRACT TRUNCATED AT 400 WORDS)

Isolation of amaranth flour proteins by fractionation procedures and sonication

The use of whole and defatted amaranth flour for protein isolation of Osborne fractions is described. Extractability of prolamins, the minor fraction, increased from 2.8 to 5% by adding a reducing agent. Glutelins proved to be poorly solubilized (3.3%) in dilute acetic acid, but they reached a high solubility value (40.8%) using a borate buffer in the presence of a reducing agent and a detergent; solubility remarkably declined without the latter two chemicals. Sonication (a fast and simple technique) in the presence of a detergent proved to be more efficient, compared with stirring, for extractability of total unreduced proteins.