Integral Chemical Analysis of the Amaranth (Amaranthus greggii S. Wats)

Abstract

The objective of this work was to obtain information on Amaranthus greggii S. Wats., related to its nutritional value, its agricultural application as leaf vegetable and for animal consumption. The following variables were analyzed: dampness, ashes, protein, mineral, ethereal extract (fat), brute fiber, oxalic acid, nitrates and carbohydrates.

Introduction

One of the species of the genus Amaranthus whose study is of a high interest due to its economical and nutritional value, has been identified botanically as Amaranthus greggii S. Wats. The excellent qualities of some annual amaranth as vegetables, owing to their nutritional value and pleasant taste, have also been determined (Castañeda et al., 1987).

Experimental Area

The green material of amaranth was dried in a stove with air forced to 60 °C until stable, and was then ground and dehydrated. Different types of chemical assays were carried out: dampness, ashes by calcination in muffle at 550 °C (Pearson, 1976), proteins by the Kjeldahl method (N x 6,25) (Skoog, West and Holler, 1995); Ca and Mg by complexmetric (Hamerly et al., 1984), P and Fe by colorimetry (Jackson, 1964), ethereal extract (extraction by Soxhlet), gross fiber and oxalate following (AOAC 1984), nitrate by colorimetry (Cataldo et al., 1975) and carbohydrates (according to difference).

Results and Discussion

The chemical composition determined on dried basis of leaves of A. greggii, is detailed on

Table 1. Proximal Chemical Composition of the tested A. greggii, confronted with A.mantegazzianus and spinach.

	A. greggii	A. mantegazzianus	Spinach
Dampness %b.s.	8.83 +-0.056	10.13	7.81
Ashes % b.s.	26.80 +-0.370	25.14	28.18
Gross Protein %b.s.	28.28 +-0.349	28.44	28.60
Gross Fiber %b.s.	13.25 +-0.343	12.14	7.75
Ethereal extract %b.s.	2.18 +-0.361	3.59	4.79
Calcium % b.s.	1.28 +-0.219	2.27	1.03
Magnesium % b.s.	0.62 +-0.190	0.67	1.10
Phosphorus %b.s.	0.62 +- 0.153	0.69	0.89
Iron mg % b.s.	45.15 +- 0.204	45.2	41
Carbohydrates1 % b.s.	20.66 +-0.730	20.56	22.87

¹They were determined by difference.

; the data were compared with the data obtained by Cattaneo et al. (1994) and Arellano et al. (1992) for A. mantegazzianus and spinach.

It was observed that A. greggii leaves have a protein content similar to spinach and A. mantegazzianus has values which surpass other types of amaranth (Rawate,1983).

The relatively high value of ashes denotes important contents of minerals, having an outstanding content of calcium and magnesium in A. greggii, which surpasses spinach and A. mantegazzianus, although inferior to the ones found by Rawate. Comparing the value of the content of iron with other amaranths, it was observed that its content is high, the values were similar to A. mantegazzianus and superior to spinach (Castañeda et al.,1987). The percentages of phosphorus found in the foliage during the analysis were near the ones mentioned by Troiani et al. (1992).

The results obtained for nitrate and oxalate in A. greggii compared with the results obtained by Gomez et al. (1986) and Arellano et al. (1992) for A. mantegazzianus and spinach are shown in

Table 2. Antinutrients of the tested A. greggii, confronted with A. Mantegazzianus and spinach.

Antinutrients	A. greggii	A. mantegazzianus	Spinach
Oxalate % b.s.	3.15 +-o.331	4.92	9.3
Nitrate % b.s.	0.18 +- 0.062	0.63	1.22

; the values are below the ones considered as toxic (Avila et al., 1987).

The analysis performed on Amaranthus greggii show similar values to the blanks which allows us to infer that this species is another alternative to the human diet.